CAPE CHEMISTRY UNIT 1 LABS
CAPE Chemistry SBA Format
Date: Top line to the left
Page #: Top line to the right
Title: As given by lecturer
Aim: As given by lecturer
Apparatus: can be listed in paragraph format to save space
Method: Must be in past tense and in paragraph format
Results: where tables are used they must have a proper title that is not ambiguous e.g ‘TABLE
SHOWING THE TITRE VALUES OBTAINED DURING THE NEUTRALIZATION OF 0.1M
NaOH’ and NOT ‘TABLE SHOWING RESULTS OBTAINED DURING EXPERIMENT’
Calculations: (If required)
Discussion: Must be in paragraph format and past tense where possible
Sources of Error/limitations/assumptions:
Conclusion: Usually a couple sentences. It must relate to your aim.
Table of contents
Ensure that you keep your table of content up to date.
PLANNING AND DESIGNING LAB WRITE UP
The format of ALL plan and design reports should be as follows
Problem Statement/Observation:
Title:
Date:
Hypothesis:
Aim:
Apparatus and Materials:
Variables:
•
Controlled
•
Manipulated
•
Responding
Method:
Expected results: (tabular form for display of results and a sentence or two stating what you are
expecting based on your hypothesis)
Treatment of results:
Discussion:
Sources of error / precautions / limitations and areas of improvement (if any)
LAB 1 (To be done in groups of 2)
Skill assessed: ORR
Date: 20th September, 2019
Title: Flame tests
Aim: To observe the characteristic colors produced by certain metallic ions when vaporized in a flame
and then to identify an unknown metallic ion by means of its flame test.
Materials:





Bunsen burner
Safety glasses
Beaker with water
Wooden splints
Solutions (1.0 mol/L) of the following metal salts
 barium chloride
 calcium chloride
 copper(II)chloride
 sodium chloride
 potassium chloride
 magnesium chloride
 zinc chloride
 iron (II) chloride
 sodium chloride /potassium chloride mixture
 unknown A
 unknown B
Procedure:
1. Work in pairs to carry out the test on each solution at the workstations set up.
2. At your first workstation, light the Bunsen burner and open the air vent to obtain a non-luminous
flame with two blue cones.
3. Remove one of the wooden splints that have been soaking in the metal salt solution labeled on the
beaker
4. Carefully place the end of the wooden splint that was soaked in the metal salt solution at the top of the
inner blue cone. Record the color and intensity (bright/faint) of the flame in the data table. The color
given off by the salt is the initial color observed, not the yellow-orange color produced by the burning
wood. (To avoid burning the wood, wave the splint through the flame rather than holding it right in
the flame).
5. If more observations are needed, dip the clean end of the wooden splint in the solutions for a few
minutes and repeat. Otherwise, discard the wooden splints in beaker of water at the end of the
experiment.
6. Repeat with the other salts at the different workstations. Be sure to record the colors as precisely as
possible
Results: Record your results in a suitable table
Discussion:
Analyze the data obtained using the following questions as guidelines. Questions do not have to be
answered in the order given but you should organize your discussion so that it flows. From one
point to the next.
1. Explain how the colors observed in the flame tests are produced.
2. Why do different chemicals emit different colors of light?
3. List the colors observed in this lab from the highest energy to the lowest energy.
4. List the colors observed in this lab from the highest frequency to the lowest frequency.
5. List the colors observed in this lab from the shortest wavelength to the longest
wavelength.
6. What is the relationship between energy, frequency, and wavelength?
7. Based on the results of your experiment, what metal is found unknown A and unknown
B? Explain.
8. Can a flame test be used to determine the identity of unknowns in a mixture? Why or
why not? (refer to results from the experiment)
9. Account for cases where a distinct flame color and intensity was not observed.
10. Give relevant sources of errors (at least 2) and limitations.
Conclusion: A statement related to the aim of your experiment
LAB 2
Skill assessed: O/R/R
Date: 4th October, 2019
Title: Physical properties of ionic and covalent compounds.
Aim: To determine the physical properties of ionic and covalent compounds
Apparatus/ material: Solid samples of A, B, C and D, 12 test tubes, test tube rack and holder,
glass rod, 25cm3 measuring cylinder, spatula, Bunsen Burner, electrical circuit, propanone,
distilled water.
Method:
1. Add a small spatula of sample A to a test tube and heat gently at first and then strongly until
no further change is observed.
2. Add a small spatula of sample A to 20cm3 of distilled water in a test tube. Test the resulting
mixture for electrical conductivity. Record your observations on solubility and electrical
conductivity.
3. Repeat step 3 using propanone instead of water.
4. Repeat steps 1 – 3 using samples of B, C and D.
Results: Record your results in a suitable table.
Discussion: Should include but not limited to
1. Principles associated with the formation of ionic and covalent bonds.
2. Identify which sample(s) are ionic and which are covalent.
3. Justify your classification of substance A –D by account for the observations made based
on the forces of attraction present in the substances analyzed.
4. Identify possible sources of errors and limitations (at least one each).
Conclusion:
LAB 3
Skill assessed: M/M; A/I
th
Date: 18 October, 2019
Title: Titrating NaOH with HCl using methyl orange indicator.
Aim: To determine the percentage mass of NaOH in B1
Apparatus/ Material:
A1 – 0.1 moldm-3 HCl, B1- Solution containing 60gdm-3 Na2CO3/NaCl mixture, methyl orange
indicator, 250cm3 volumetric flask, 25cm3 pipette, two 50 cm3 burette, three 250 cm3 conical
flask, funnel, White tile, wash bottle with distilled water.
Method:
1. Using a burette, place 30.00 cm3 of B1 in a 250cm3 graduated flask. Make up the contents of
the flask to the mark using distilled water to produce B2.
2. Place A1 in a second burette.
3. Pipette 25cm3 of B2 into a conical flask. Add 2 drops of methyl orange indicator and titrate
with A1 until the first permanent color change is observed.
Treatment of results/calculations
1. Calculate the average volume of A1 required to neutralize 25cm3 of B2.
2. Write an equation for the reaction of NaOH with HCl.
3. Calculate the number of moles of HCl (A1) used.
4. Determine the number of moles of NaOH in 25cm3 of B2.
5. Calculate the number of moles of NaOH in 250cm3 of B2.
6. Calculate the concentration of NaOH in B1 in i) moldm-3 ii) gdm-3
7. Determine the % by mass of NaOH in B1.
Discussion
Thoroughly discuss your results
Points to include:



Definition of titration.
Explanation of the reaction occurring.
Concept of end point/equivalence point (in relation to the titre value obtained) and choice
of indicator.


Why titration is a suitable method.
Sources of error: At least 2 appropriate.
Conclusion:
Lab 4
Skill Assessed: M/M; A/I
Date: 1st November, 2019
Title: Redox titration
AIM: To determine the concentration of a solution of hydrogen peroxide
Materials/ apparatus:
0.020 moldm-3 potassium manganate (VII) solution (75 cm3), H2O2 stock solution (10cm3), 1M
sulphuric acid solution (40cm3) distilled water, 250cm3 volumetric flask (1), beakers to collect
solutions (3), conical flasks (3), 50cm3 burette (1), 25 cm3 pipette (1), pipette filler, white tile,
retort stand, 10 ml measuring cylinder (2)
Procedure
1. Prepare 250 cm3 of a solution of hydrogen peroxide by adding 7.5 cm3 of the stock solution
supplied to the volumetric flask and diluting to the required volume.
2. Pipette 25.0 cm3 of this solution into a conical flask.
3. Add 10 cm3 of 1 mol dm-3 sulphuric acid in a measuring cylinder.
4. Titrate the mixture against the potassium manganate (VII) until a permanent pale pink colour
appears in the conical flask.
5. Record the titre volume and repeat until concordant values are obtained.
6. Write your results in the table below and answer the questions that follow.
Results
Burette
Reading/cm3
Final
Initial
Volume
used/cm3
Trial
1
2
Treatment of results/Calculations
1. Write the relevant half equations for the reaction occurring.
2. Using the two half equations from question 1, write the full balanced ionic equation.
3. If the stock solution of hydrogen peroxide had a molar concentration of 1.67 mol dm-3,
determine the molar concentration of the hydrogen peroxide solution prepared by you.
4. Determine the molar concentration of the hydrogen peroxide solution prepared by you
using your titration results.
5. Hydrogen peroxide is sold using terms such as “20-volume”. This means that any
volume of H2O2 will decompose the produce 20 times that volume of oxygen gas (eg.
1cm3 of hydrogen peroxide would produce 20 cm3 of oxygen upon decomposition).
Using the molar concentration of the stock solution of 1.67 mol dm-3, determine what
designation you would assign this hydrogen peroxide.
Discussion (should include)
1. Relevant definitions
2. Make reference to relevant equations to identify
 Changes in oxidation states,
 what is oxidized/ reduced
 oxidizing and reducing agents
3. Account for any differences in values for 3 and 4 under treatment of results.
4. Sources of errors/
conclusion:
LAB 5 (P&D # 1)
Skill assessed: P/D
Due date: 5th November, 2019 along with Lab 4
Problem Question:
John and Sarah are interested in the oxidizing abilities of Cu2+, Pb2+ and Ag+. Plan and design an
experiment to compare the relative oxidizing abilities of these metal ions.
Hypothesis: this is a statement based on the observation/problem that can be tested.
Title:
Aim:
Apparatus/Materials:
Variables: Independent variable (the one you are controlling), Dependent variable (the one you
will be recording results for), Controlled variables (all other variables that must be kept constant)
Method:

Present tense

List all steps in point form
Expected results: shows how results will be recorded (tables, graphs etc), if tables are being
used then draw empty tables with headings and title.
Treatment of results: If graphs are being used state which variable should be plotted on which
axis.
Outline steps to be taken for any calculations
Describe the results that are expected if applicable
State your inferences
Discussion: Explain the results that should be expected (if known) and write relevant equations.
Limitations/Assumption: shortcomings of you design which may become sources of error and
list any assumptions made.
LAB 6
Date: 15th November
Skill assessed: AI / MM
(To be done in groups of 4)
Skills assessed: M/M and ORR
N.B. For your M/M skill, you will be assessed on your use of the top loading balance, as
well as general lab measurement skills (measuring cylinder, thermometer readings, use of
reagents etc.)
NaOH rapidly absorbs moisture from the air to form a corrosive liquid so conduct this part
of the experiment quickly but carefully! The persons weighing the NaOH must wear
gloves!
Title: Hess’ Law
Aim: To determine the standard enthalpy changes of solution, neutralization and reaction for
sodium hydroxide and use them to verify Hess’ law.
Apparatus: Top loading balance, spatula (will be in container with NaOH), weighing paper (2),
solid sodium hydroxide, 2M sodium hydroxide solution (100 ml), 2M hydrochloric acid (100ml),
0.25M hydrochloric acid (200ml), thermometer (2), styrofoam cup (3), 250 - 300 ml beaker (6),
100 ml measuring cylinder (1), distilled water (200ml)
Method:
Standard enthalpy of neutralization of NaOH(aq) and HCl(aq)
1. Place the styrofoam cup into the 250/300ml beaker.
2. Pipette 25 ml of 2M NaOH solution into the styrofoam cup. Allow it to stand and record
the constant temperature reached.
3. Rinse a clean burette with a small volume of the 2M HCl solution and then fill the
burette with the remaining 2M HCl solution (ensure that the tip is filled and the funnel
removed after filling)
4. Run 5.0ml of the HCl from the burette into the styrofoam cup.
5. Stir the mixture well using the thermometer and record the highest temperature reached.
6. Add another 5.0ml portion of HCl to the styrofoam cup, stir the mixture and record the
highest temperature.
7. Repeat step 6 until all 50 ml are used up.
8. Record your results in a suitable table
Standard enthalpy of solution of NaOH (s)
1.
2.
3.
4.
5.
Place the styrofoam cup into a 250/300 ml beaker.
Using the measuring cylinder, add 200 ml of distilled water to the styrofoam cup
Measure and record the steady temperature of the water.
Record the mass of an empty sheet of weighing paper.
Add between 2 – 3 g of solid sodium hydroxide to the weighing paper and record the
total mass.
6. Quickly add the sodium hydroxide to the distilled water in the styrofoam cup
7. Stir the mixture gently using a thermometer until all of the solid has dissolved
8. Record the highest temperature reached.
9. Reweigh the weighing paper and record its mass.
10. Record your results in a suitable table
Standard enthalpy of reaction between NaOH(s) and HCl(aq)
1.
2.
3.
4.
5.
Place the styrofoam cup into a 250 ml beaker.
Using the measuring cylinder, add 200 ml of 0.25M HCl to the styrofoam cup
Record the steady temperature of the acid.
Record the mass of a sheet of weighing paper
Add between 2 – 3 g of solid sodium hydroxide to the weighing paper and record the
total mass.
6. Quickly add the sodium hydroxide to the acid in the cup.
7. Stir the mixture gently using a thermometer until all of the solid has dissolved
8. Record the highest temperature reached.
9. Reweigh the weighing paper and record its mass.
10. Record your results in a suitable table
Results:


Record your results in suitable tables. Ensure that your tables are numbered, enclosed,
easy to read, have suitable titles that are underlined, have suitable headings and units.
Draw a graph of temperature (y-axis) vs volume of 2M HCl added (x – axis) for the
standard enthalpy of neutralization. From your graph determine the equivalence point of
the titration and clearly label this point on your graph.
Calculations:
1. Calculate the standard enthalpy changes of neutralization, solution and reaction using
your knowledge of energetics and the results obtained from the experiments (Assume the
specific heat capacity of the polystyrene cup is negligible and that the specific heat
capacity of the solution is 4.18JK-1g-1.) For the standard enthalpy change of reaction,
determine which reagent is limiting and use its number of moles to calculate the standard
enthalpy change of reaction.
2. Write the net ionic equations for all reactions
3. Use your ionic equations for neutralization and solution to construct a Hess’ law diagram
to determine the value for the enthalpy change of reaction for sodium hydroxide with
hydrochloric acid
4. Use your Hess’ law diagram along with the calculated values for standard enthalpy
change of neutralization and solution to calculate a second value for the standard
enthalpy change of reaction for sodium hydroxide with hydrochloric acid.
Discussion:
Your discussion should include but is not limited to:


Comparisons between the value for the enthalpy of reaction calculated from the
experiment with that obtained using Hess’ law and account for any differences
Comparisons between your experimental values for each enthalpy with theoretical ones
and account for any differences.
Conclusion:
LAB 7 (to be done in pairs)
Date: 29th November, 2019
Skills assessed: ORR
Title: Rates of Reaction
Aim: To determine the effect of concentration on the rate of the reaction between sodium
thiosulphate and HCl
Apparatus: per pair of students
0.5M HCl – 110ml
0.15 M Na2S2O3 – 130ml
Distilled water
Beaker (2)
Stopwatch/Timer (1)
25ml measuring cylinder (1)
50ml measuring cylinder (1)
Method: (This lab will be done in pairs – 1 person will conduct the 1st two conc.s while the
other does the 2nd two concs. You will then swap results.) This instruction is not to be
included in write up.
1. Measure 50ml of sodium thiosulphate into the 50ml measuring cylinder and then add it to
the beaker.
2. Place the conical flask/beaker on a paper given.
3. Record the initial temperature of the sodium thiosulphate solution
4. Measure 25 ml of 0.5M HCl into a 25ml measuring cylinder
5. Add the HCl to the conical beaker and immediately start timing
6. Swirl the contents of the flask/beaker once and let it stand on the white tile
7. Stop timing when the writing on the paper is no longer visible through the solution
8. Record the time taken in seconds
9. Wash the solution down the sink with plenty of water
10. Repeat the experiment at three different concentrations of sodium thiosulphate (refer to
the results table)
11. Use 1/time taken as a measure of the relative rate
Expt.
#
Volume of
Volume
0.15M sodium
of
thiosulphate/ml distilled
water/ml
Volume of
HCl/ml
Concentration Time
of
taken/s
thiosulphate
solution/M
Relative
rate/s-1
1
2
3
4
50
35
25
15
0
15
25
35
25
25
25
25
N.B. Add the required volume of thiosulphate to the 50ml measuring cylinder and then
make it up to the 50 ml mark with distilled water, where applicable.
1. Calculate the concentration of Na2S2O3 in each experiment using the formula
C1V1 = C2V2, where C1 = initial concentration of 0.15M, V1 = volume of 0.15M used, V2 =
volume of thiosulphate + distilled water
2. Plot a graph of concentration (y-axis) vs time taken (x-axis)
3. Plot a graph of relative rate (y-axis) vs concentration (x-axis)
Discussion:
A complete analysis of your results (inclusive of your graphs) based on the information learnt
during the study of Rates of Reactions.
Lab 8
Date: 13th December, 2019
Skills assessed: M&M, AI
Title: Rates of reaction – effect of temperature
Aim: To determine the effect of temperature on the rate of a chemical reaction and the value of
activation energy of the reaction.
Apparatus/ material: 2M HCl (120 ml), distilled water, 5 strips magnesium metal each 2cm
long, water bath, thermometer (1), 250 ml beaker (2), stop watch (10, measuring cylinder (1
50ml and 1 10ml)
Procedure
1. Measure 20 cm3 of 2M HCl and then measure 5 cm3 of water and pour both into the beaker
provided. Record the temperature of the resulting solution.
2. Simultaneously add the strip of magnesium metal to the acid and start the stop-watch. (be
cautious not to directly inhale gas given off).
3. Stop recording the time as soon as all of the metal strip has dissolved.
4. Discard the mixture and wash the beaker thoroughly with soap, tap water and then with
distilled water.
5. Repeat step 1, then setup up a water bath and heat the contents of the beaker to 50 °C. Use a
thermometer to monitor the temperature.
6. Quickly remove the beaker and place on the counter, allow the temperature to drop to 45 °C
and simultaneously add the magnesium strip and start the stop-watch and again stop when all the
metal has dissolved and repeat step 4.
7. Repeat the experiment 3 more times, raising the temperature by 10 °C as shown in the table
below.
Caution: Take care in removing hot beakers from the water bath.
Results:
Experiment #
1
2
3
4
5
Temperature /°C
room temp. (please note the
temperature of the mixture)
45
55
65
75
Treatment of results
Time (s)
1. Complete the table by calculating
i) 1/time ii) the temperature in Kelvin iii) 1/K (K-1) iv) ln rate (which is the ln of the value 1/t)
for each of the experiments.
Experiment #
Temperature
(K)
1/K (K-1)
1/t (s-1)
ln (1/t)
1
2
3
4
5
2. Plot a line of best fit of ln 1/t vs 1/K and calculate the gradient of the line.
3. The gradient of the line corresponds to the formula – EA / R where EA is the activation
energy and R is the molar gas constant 8.314 J K-1 mol-1. Use the gradient of the line to
calculate the activation energy for the reaction of magnesium metal and dilute HCl.
Discussion
Discuss your results based on collision theory and the Boltzman distribution. Should include
relationship of concentration to i. time ii i/t. Also include the value of the activation energy
obtained from the graph and the significance of activation energy on the reaction carried out.
Also discuss what you observe in the rate with a 10o rise in temperature. (Research what is
expected to happen to the rate of a reaction with a 10o rise in temperature and account for any
deviation of your results from this trend)
Sources of errors/ limitations/assumptions
(Please remember that points mentioned in your discussion should be linked to the reaction
carried out. So do not just give definitions without relating it to this specific experiment)
LAB 9
Due 21st January
This lab is to be completed over the Christmas break and will be submitted on Jan 21th
along with lab 10.
Skill assessed: Planning and designing
Problem:
The substance hydrogen peroxide decomposes naturally to water and oxygen gas. You are given
THREE substances X, Y and Z and are told that they catalyse the decomposition process of
hydrogen peroxide. Your task is to determine which of the three substances is the most efficient
catalyst.
Hypothesis: this is a statement based on the observation/problem that can be tested.
Title:
Aim:
Apparatus/Materials:
Method:

Present tense

List all steps in point form
Variables: Independent variable (the one you are controlling), Dependent variable (the one you
will be recording results for), Controlled variables (all other variables that must be kept constant)
Expected results: shows how results will be recorded (tables, graphs etc), if tables are being
used then draw empty tables with headings and title.
If graphs are being used state which variable should be plotted on which axis.
Outline steps to be taken for any calculations
Describe the results that are expected if applicable
State your inferences
Discussion: Explain the results that should be expected (if known) and write relevant equations.
Limitations/Assumption: shortcomings of you design which may become sources of error and
list any assumptions made.
SEMESTER 2
Lab 10 (To be done in pairs)
Date: 17th January, 2019
Skills assessed: AI
N.B.


The cobalt chloride equilibrium mixture contains concentrated HCl so the person who
will be handling it needs to wear gloves. Be careful when washing the test tubes after the
experiment as well.
AgNO3 decomposes in sunlight, so only collect this solution when you are at test tube #4.
Background information:
Title: Le Chatelier’s Principle
Aims:
1. To determine the effect of changes in temperature and concentration on the position of
equilibrium in a cobalt chloride system
2. To determine the effect of changes in pH on the position of equilibrium in a chromate
system
Apparatus:
0.1M equilibrium mixture of cobalt chloride (~10 ml), 0.1M equilibrium mixture of acidified
potassium chromate (~10ml), AgNO3 solution (10 ml), 6M HNO3 (10 ml) 10% NaOH (10 ml),
concentrated HCl (CORROSIVE! - will be administered by teacher), test tubes (8), test tube rack
(2), test tube holder (1), bunsen burner, matches, ice bath, droppers, 50 ml beakers (5)
Method:
Effect of changes in temperature and concentration on cobalt chloride system
1. Divide 10 ml of the cobalt equilibrium solution amongst 5 test tubes.
2. Record the initial color of all the solutions
3. Label one of the test tubes ‘control’. (This test tube will be used to compare the color
changes in each experiment.)
4. Place the 2nd test tube in the ice bath and leave it to cool until the end of the other
experiments.
5. Heat the 3rd test tube in the bunsen burner flame (moderate flame) by wafting it back and
forth until a color change occurs.
6. To the 4th test tube add the silver nitrate solution dropwise at first and then in excess.
7. To the 5th test tube add concentrated HCl solution in excess.
8. Record all observations in a suitable table.
Effect of changes in pH on chromate system
1. Divide 10 ml of the acidified potassium chromate equilibrium solution amongst 3 test
tubes.
2. Record the initial color of all the solutions.
3. Label one of the test tubes ‘control’. (This test tube will be used to compare the color
changes in each experiment.)
4. To the 2nd test tube add an equal volume of 6M HNO3.
5. To the 3rd test tube add an equal volume of 10% NaOH solution.
6. Record all observations in a suitable table.
Results:
Discussion:
Your discussion should include:



Key definitions
Explanations for all your observations based on Le Chatelier’s principle (with relevant
equations)
Possible sources of error (explaining their impact on your results)
Conclusion:
Lab 11
Date: 31st January, 2019
Title: Equilibrium constant
Aim: To determine the equilibrium constant for the formation of ethyl ethanoate
Apparatus/material: 2 moldm-3 NaOH accurately standardized, 1 moldm-3 HCl, glacial ethanoic
acid, ethanol, 50 cm3 burette, phenolphthalein indicator, 100cm3 conical flask and stopper
Procedure:
1. Set up in duplicate, 5cm3 of ethanol, 5cm3 of ethanoic acid and 5 cm3 of HCl in a conical flask
and stopper immediately.
2. Shake the mixture well and allow to stand for a few days to reach equilibrium.
3. Add two drops of phenolphthalein to the equilibrium mixture in the conical flask and titrate
with 1 moldm-3 NaOH.
4. Repeat titration with second sample.
5. To make allowance for the catalyst, titrate 5cm3 of the HCl with NaOH.
Results:
Table showing Final burette reading, initial burette reading and volume of NaOH used for
sample 1 and 2 and HCl catalyst.
Calculations
1. Calculate the average titre volume using the two equilibrium samples.
2. Calculate the number of mole of NaOH in average titre.
3. Calculate the number of moles of NaOH that reacted with the HCl catalyst (Write balanced
equation).
4. Using your answers to questions 2 and 3 calculate the moles of NaOH that reacted with
ethanoic acid in the equilibrium mixture.
5. Determine the number of moles of ethanoic acid at equilibrium. (Write equation).
6. Calculate the initial number of moles of ethanoic acid in the 5 cm3 used. (Density of ethanoic
acid = 1.049gcm-3).
7. Calculate the initial number of moles of ethanol in the 5 cm3 used (density of ethanol = 0.789
gcm-3).
8. Calculate the equilibrium constant Kc including units.
Discussion: should include but not limited to the following points
Thoroughly discuss the chemical principles on which this lab is based (inclusive of principles of
dynamic equilibrium, equilibrium constants, role of HCl, why it was important to determine the
number of moles of HCl that reacted wit NaOH).
Give sources of errors, limitations and assumptions.
Conclusion
Lab 12: (To be done in groups of 5)
Date: 14th February, 2019
Title: period 3 and group 2 elements
Skill Assessed: ORR
Title: Period 3 and Group 2 Elements
Aim: To describe the trend in solubility and acid/base nature of some of the oxides, chlorides and
hydroxides of period 3 and group 2
Apparatus: 250ml beakers (10), spatula, magnesium oxide, aluminium oxide, silicon dioxide,
calcium oxide, sodium chloride, magnesium chloride, aluminium chloride, sodium hydroxide,
magnesium hydroxide, calcium hydroxide, barium hydroxide, universal pH papers, thermometer,
tap water, top pan balance, weighing paper.
Method:
Solubility and Acid/Base Nature of oxides of period 3 and group 2
1.
2.
3.
4.
5.
6.
7.
8.
Add approximately 100ml of tap water to an empty 250ml beaker
Record the temperature of the water
Record observations of the solid magnesium oxide MgO
Using the balance, weigh approximately 1 g of magnesium oxide and add it to the water
in the beaker.
Stir the solution using the thermometer and record any temperature changes
Record observations about the solubility of the oxide
Test the pH of the mixture using universal pH paper and record the results
Repeat steps 1-7 using aluminium oxide Al2O3, calcium oxide CaO and silicon dioxide
SiO2. – Approximately 100ml of tap water was added to an empty 250ml beaker. The
temperature of the water was recorded. Observations of the solid magnesium oxide were
recorded. With the use of the balance, approximately 1g of magnesium oxide was
weighed and was added to the water in the beaker. The solution was stirred using the
thermometer and any change in temperature was recorded. Observations about the
solubility of the oxide was recorded. The pH of the mixture was tested using universal pH
paper and the results were recorded. The previous procedure was repeated using
aluminium oxide, calcium oxide and silicon dioxide.
Solubility and Acid/Base Nature of chlorides of period 3
1.
2.
3.
4.
5.
6.
7.
8.
Add approximately 100ml of tap water to an empty 250ml beaker
Record the temperature of the water
Make observations of the solid sodium chloride NaCl
Using the balance, weigh approximately 1 g of sodium chloride and add it to the water in
the beaker
Stir the solution using the thermometer and record any temperature changes
Record observations about the solubility of the chloride
Test the pH of the mixture using universal pH paper and record the results
Repeat steps 1-7 using magnesium chloride MgCl2 and aluminium chloride AlCl3. –
Approximately 100ml of distilled water was added to an empty 250ml beaker. The
temperature of the water was recorded. Observations of the solid sodium chloride were
made. With the use of the balance, approximately 1g of sodium chloride was weighed
and was added to the water in the beaker. The solution was stirred using the thermometer
and any change in temperature was recorded. Observations about the solubility of the
chloride was recorded. The pH of the mixture was tested using universal pH paper and
the results were recorded. The previous procedure was repeated using magnesium
chloride and aluminum chloride.
Solubility and pH of hydroxides of period 3 and group 2
(Wear gloves when handling these hydroxides and avoid contact with your skin)
1.
2.
3.
4.
5.
6.
7.
8.
Add approximately 100 ml of tap water to an empty 250ml beaker
Record the temperature of the water
Make observations of the solid sodium hydroxide NaOH
Using the balance, weigh approximately 1 g of sodium hydroxide and add it to the water
in the beaker
Stir the solution using the thermometer and record any temperature changes
Record observations about the solubility of the oxide
Test the pH of the mixture using universal pH paper and record the results
Repeat steps 1-7 using magnesium hydroxide Mg(OH)2, calcium hydroxide Ca(OH)2
and barium hydroxide Ba(OH)2. - Approximately 100ml of distilled water was added to
an empty 250ml beaker. The temperature of the water was recorded. Observations of the
solid sodium hydroxide were made. Approximately 1g of sodium hydroxide was weighed
with the use of the balance and was added to the water in the beaker. The solution was
stirred using the thermometer and any change in temperature was recorded. Observations
about the solubility of the oxide was recorded. The pH of the mixture was tested using
universal pH paper and the results were recorded. The previous procedure was repeated
using magnesium hydroxide, calcium hydroxide and barium hydroxide.
Results:
Record your results in suitable table/s
Discussion:





Describe and explain the trends in solubility of the oxides, chlorides and hydroxides of
period 3
D7escribe and explain the trend in the acid/base nature of the oxides, chlorides and
hydroxides of period 3
Describe and explain the trends in solubility of the oxides and hydroxides of Group 2
Describe and explain the trend in the acid/base nature of the oxides and hydroxides of
Group 2
Sources of Error: 1. Seeing a different color on the pH indicator… Not being able to
observe the correct pH indicator color for solutions. So, when comparing the pH paper of
the solution to the pH chart, a wrong color range was chosen.
Conclusion:
Lab 13: Qualitative analysis of halides
Date:28th February, 2019
Skill Assessed: A/I
This lab will be done in groups of five
Title: Qualitative Analysis of the Halide Salts
Aim: To identify the halide ions by their reactions with concentrated sulphuric acid and aqueous
silver nitrate
Apparatus: test tubes (7), test tube rack (1), 50ml beakers (7), droppers (3), solid samples of
halide salts KX, KY and KZ, distilled water, nitric acid (20 ml), aqueous silver nitrate (10 ml),
aqueous ammonia (20 ml), concentrated sulphuric acid (~5 ml) , spatula, test tube holder, pH
paper
Method:
Reaction of the halides with concentrated sulphuric acid
1. Using a spatula, add a small amount of solid KX to a dry test tube
2. Holding the test tube in a test tube holder, add concentrated sulphuric acid drop-wise to
the test tube until the reaction starts (stop adding acid once the reaction starts!)
3. Test any gases given off with moistened pH paper
4. Record all observations (color of gases/solutions/solids, scent of gases, color changes to
and pH of pH paper)
5. Repeat steps 1- 4 with the solids KY and KZ
All observations (color of gases/solutions/solids, scent of gases, color changes to and pH of pH
paper) were recorded. The previous procedure was repeated with the solids KY and KZ.
Reaction of the halides with aqueous silver nitrate
1. Fill 3 beakers with approximately 50ml of distilled water and dissolve a spatula full of
KX, KY and KZ into each beaker.
2. Rinse the four remaining test tubes with soap, followed by distilled water, followed by a
final rinse with nitric acid
3. Add approximately 1ml of distilled water to one of the test tubes. (This will serve as your
control)
4. Add approximately 1 ml of the solution of KX to another test tube
5. Add 5 drops of nitric acid to the test tube and shake to ensure proper mixing
6. Add silver nitrate solution drop-wise to the test tube until a precipitate forms. Shake the
test tube after each drop.
7. Record the color of the precipitate formed
8. Add dilute aqueous ammonia in excess to the test tube noting if any of the precipitate redissolves. Shake the test tube after adding the ammonia.
9. Record your observations.
10. Repeat steps 4-8 using the remaining solutions of KY and KZ.
Results:
Discussion:
Your discussion should include:


Identification of the halide ions present with explanations for your deductions
Balanced equations with state symbols for reactions occurring


Identification of products observed when the halides react with concentrated sulphuric
acid
Identification of the type of reaction occurring and identification of what has been
oxidized/reduced where applicable.
Conclusion: Halide ions in concentrated sulphuric acid and aqueous silver nitrate.
Lab 14 (This lab is to be done in pairs)
Date: 13th March, 2019
Skill Assessed: M/M
Title: Ligand Exchange in Transition Metals
Aim:
1. To exchange water ligands in aqueous copper sulphate, aqueous cobalt chloride and
aqueous iron (III) chloride with ammonia, chloride ions and thiocyanate ions
2. To determine the ease with which ammonia, chloride ions and thiocyanate ions can be
exchanged for water ligands
Apparatus: test tubes (12), test tube rack (1), 50ml beakers (3), droppers (3)(these are already in
the solutions), aqueous copper (II) sulphate (10 cm3), aqueous cobalt (II) chloride (10 cm3),
aqueous iron (III) chloride (10 cm3), distilled water, aqueous ammonia, concentrated HCl (very
corrosive- handle with care!), aqueous potassium thiocyanate solution, 10cm3 measuring
cylinder (2)
Method:
1. Thoroughly clean all test tubes with soap and water.
2. Using a measuring cylinder, add 1 cm3 of the aqueous copper sulphate solution to 4 of the
test tubes.
3. To the 1st test tube add aqueous ammonia in excess until a precipitate/color change
occurs. Shake the test tube and record all observations.
4. To the same test tube add distilled water in excess and record observations.
5. To the 2nd test tube add concentrated HCl in excess and shake the test tube. Record the
formation of any precipitate/color change.
6. To the same test tube, add distilled water in excess and record any changes.
7. To the 3rd test tube add aqueous potassium thiocyanate in excess and shake the test tube.
Record the formation of any precipitate/color change.
8. To the same test tube add distilled water in excess and record observations.
9. The 4th test tube is the control.
10. Repeat steps 2 – 9 using aqueous cobalt (II) chloride and aqueous iron (III) chloride.
Results:
Discussion should include





Key definitions – transition elements, ligands, complexes, stability constants
Include balanced equations for the ligand exchange reactions occurring
Explain why the color changes and/or precipitates are observed
Deduce which ligands have higher stability constants than water based on how easily the
reactions can be reversed by adding water
Possible sources of error
Conclusion
Lab 15
Date: 3rd April, 2019
Skill Assessed: AI
Title: Qualitative Analysis
Aim: To distinguish between a sample of aluminum chloride, magnesium sulphate and lead
nitrate.
Apparatus: test tubes (6), test tube rack (1), 50ml beakers (3 per pair), teat pipettes (2), test tube
holder, blue and red litmus paper, HCl, HNO3, BaCl2, KI, acidified potassium dichromate,
Bunsen burner, Sample A, Sample B, Sample C, NaOH and aqueous NH3
Method:




Carry out tests outlined in the table to determine the identity of the cation and anion
present in each sample.
Use approximately 1 ml of the sample for each test carried out.
Each test should be done with a fresh sample.
Record the tests carried out and all observations.
Results: see table below
Results:
Description of Tests
1. Add NaOH drop wise to each of the three
solutions.
Record if any precipitate forms and the color
of it.
Continue to add NaOH until in excess and
note if the precipitate dissolves.
2. Add aqueous ammonia to each sample and
record if any precipitate forms and the color
of it.
Add excess aqueous ammonia and note if any
precipitate dissolves.
3. Add a few drops of potassium iodide to
each sample.
4. Add dilute NaOH and a piece of Aluminum
foil to each sample.
Heat the sample until it boils.
Test for NH3 gas by holding a piece of moist
red litmus paper over the mouth of the test
Observation
Inference
tube.
5. Add BaCl2 to each sample dropwise until a
precipitate forms.
Test the solubility of the ppt in excess dilute
HCl or HNO3
6. To a fresh sample, add sample A to the test
tube drop by drop until a precipitate forms.
Test the solubility of the ppt in excess dilute
HCl or HNO3
7. Add dilute HCl and gently warm the test
tube
Test for SO2 gas by holding a dropper
containing acidified potassium dichromate
over the mouth of the test tube.
8. Add HNO3 dropwise to each of the sample
until the pH of the solution is in the acidic
range (test with blue litmus).
Add AgNO3 dropwise until a ppt forms.
Test the solubility of the ppt in aqueous NH3
9. To a fresh sample of each solution, add
sample A dropwise until a ppt forms.
Discussion: Identify substances A, B and C giving reasons based on the tests carried out and
relevant equations.
Identify possible sources of errors and limitations (at least 2 each)
Conclusion: