Chemistry Paper 6 Final Revision:
Question 1:
Separation Methods
Solid-liquid
Solid Insoluble in
Liquid
Filtration
Liquid-liquid
Solid Soluble in
Liquid
Miscible
Liquids
Immiscible
Liquids
Solid
Fractional
Distillation
Separating
Funnel
Crystallization
Liquid
Simple Distillation
Different between Solubility & Miscibility:
Solubility is a more general term, but it is more often used to mean the ability of a solid
solute to dissolve in a g. Miscibility is used when talking about the solubility of -specifically -- liquid solutes.
-Study Diagrams well with labelling!!
Solid-Liquid (insoluble)
Filtration
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Immiscible Liquids
Separating Funnel (Density)
Solid Soluble in Liquid
Obtain the SOLID
Obtain the LIQUID
Crystallization
Simple Distillation
The Condenser cools down the vapor.
Miscible Liquids
Fractional Distillation
-What is the function of Fractionating Column? To prevent the liquid that didn’t
reach the boiling point from passing to the condenser
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Chromatography (very important)
lid
-The Major Solvent is WATER, if Dyes are insoluble in water use another solvent
(Organic Solvents) Ex: Ethanol, Propanol.
-Why do we use pencil (made from graphite) not ink in the baseline? Graphite is
insoluble in water but ink is soluble and will run up the chromatography paper.
-Why must the level of solvent be below the Baseline? To prevent dissolving of
the spots in solvent.
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Rate of reaction (Calculate volume of gas produced)
Bung
Conical flask
-What is the function of the BUNG? Prevent gas escaping
Important lab Tools
Spatula
Mortar & Pestle
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Tripod & Bunsen Burner &Crucible
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-White tile is used to see color change accurately
-How to Differentiate between:
1. Tap funnel and Burette? Burette is scaled
2. Measuring cylinder and gas jar? Measuring cylinder is scaled
Collection of gases:
Downward for gases DENSER than air ex: Cl2, HCL, CO2, SO2, NO2.
Upward for LESS DENSE than air ex: H2, NH3
Collection Over Water: For gases insoluble in water ex: CO2, SO2, H2
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Tool
Advantage
Disadvantage
Measuring cylinder
Quick
Not accurate
Pipette
Accurate
Slow, measure fixed volume
Burette
Accurate
Slow
Source of error
Improvement
Using a clock
Use a Stop watch
Doing exp. once
Repeat and take average
Using glass Beakers for
Use polystyrene cup
temp change exp.
(prevent heat loss)
Heat loss
Use lid
Using Glass beakers in
Use Crucible
high temperature exp.
Measuring cylinder
Use burette or pipette
Safety Precautions:
1. Wear goggles & gloves
2. Heat flammable substances as alcohol using a WATER BATH not BUNSEN
BURNER
3. You should use Fume Cupboard when experiment Releases toxic gases as:
Cl2, Br2, F2, I2, SO2, NO2
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Question 2
You should Read the headings well at the first!
1 You have to notice at the first
1 Reactants
2 Variable that I measure
3 Variable that I change
As you see here
Reactants: Magnesium &
sulfuric acid
Variable that I measure:
Volume of Gas Collected
Variable that I change:
Volume of distilled water
All other Variables are
constant
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2 Complete the Tables of Diagrams you have to check:
1 If the Scale is increasing UPWARD OR DOWNWARD
2 If the different between two numbers is 10 or 5 points
-Here the increasing is Downward and the difference is 10 so the point
is Equal the difference divide by 10 = 0.1
3 If Burette Reading is 0 it must be written 0.0 because Burette reads to
1 decimal place
4 take a close view to check If the Point is between two points so it will be the
number between them
Here the point is between 22 and 23 so it’s 22.5
3 Drawing the Graphs
1 Two lines meet at a point called point of intersection
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4 Most Repeated Questions In question two:
1 When you See A measuring cylinder at the first of the experiment know that it’s
a source of error it’s not accurate
-What is the improvement of using measuring cylinder? Using burette or pipette
-What is the problem of using Burette or Pipette? Slow
2 why as you add more of any substance the results are the same? Because the
Reaction Has finished
3 Explain how the results show that the reaction in Experiment 2 has stopped?
Constant stays the same at specific point
4 How to check Reliability? Repeat and compare and take average
5 If the volume of gas is measured in more times for example every 15 seconds
instead of 30 Seconds why it’s an improvement? More data, can plot a better
graph
6 Explain why the bung must be replaced immediately after any substance is
added to the boiling tube? To prevent Gas Escaping
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7 Explain how the apparatus could be altered so that the bung does not have to
be removed.
You may draw a diagram to explain your answer.
o The reaction can be started by tipping the flask
o do not have to replace / remove the
bung
o so, no gas escape
8 Explain why the conical flask was rinsed with water? to clean / to remove
residue from previous experiment
9 Explain why the conical flask is placed on a white tile? To observe the color
change accurately
10 Suggest why the experiments were done in a polystyrene cup rather than a
glass beaker? Prevent heat loss it’s an insulator
11 Suggest a different method to measure the amount of solid formed during
the experiment? Filter then wash and dry then reweigh the solid
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5 Sketch on the grid Questions
-If the experiment is used to measure temperature, Volume, mass, concentration
therefore if any variable is changed so the ending point will increase or Decrease
according to the number of Decrease or
increase
- Here the temperature Decrease it Levels
of at 9 when using half the Concentration
it levels of at 4.5
- If the Experiment is used to Measure the Rate of Reaction so Increasing or
Decreasing any variable make the curve more
or less steep with the same ending point
-Here Increasing Temperature Makes the
curve steeper and have the same ending point
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- If the Experiment is used to measure the Rate of Reaction and there’s a limiting
and excess reagent
-If we Increase or Decrease any
-If we Increase or Decrease amount
variable of excess the curve becomes
of limiting Reagent (mass or
more or less step with same ending
concentration) the curve becomes
point
more or less step with different
ending point
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Question 3 Test for ions and colors
• Positive ions are called Cations
• Negative ions are called Anions
− All cations are tested by Aqueous Sodium Hydroxide and Aqueous
Ammonia
− The Anions Don’t Follow any trend in Tests, each anion has its own test.
If the test is added in excess, we talk about solubility of Cation
− Zinc is the only cation to dissolve in both Tests
− Iron (II) Iron (III) are insoluble in both Tests
− The solubility of Chromium (III) is totally Reverse to Copper (II)
- Bromide and chloride and iodide are called HALIDES, they have the same test
also.
- If I use a wrong test for the anion it won’t affect it so NO REACTION
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1 Cations:
Cation
Ammonium
Effect of Aqueous Sodium Hydroxide
Effect of Aqueous Ammonia
(Aq. NaOH)
(Aq. NH3OH)
Ammonia produced on warming
(NH4+)
Zinc
White ppt., Soluble in excess, Giving a
White ppt., Soluble in excess, Giving
(Zn+2)
colorless solution
a colorless solution
Aluminum
White ppt., Soluble in excess, Giving a
White ppt., insoluble in excess
(Al+3)
colorless solution
Calcium
White ppt., insoluble in excess
No ppt or very slight ppt
Green ppt., Insoluble in excess
Green ppt., Insoluble in excess
Red-brown ppt., Insoluble in excess
Red-brown ppt., Insoluble in excess
Light blue ppt., insoluble in excess
Light blue ppt., soluble in excess
Green ppt., Soluble in excess
Grey-green ppt., Insoluble in excess
(Ca+2)
Iron (II)
(Fe +2)
Iron (III)
(Fe+3)
Copper (II)
(Cu +2)
Chromium
(III)
(Cr +3)
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2 Anions:
Anion
Test
Test Result
Carbonate
Acidify with Dilute acid
Effervescence, Carbon
(CO3-2)
dioxide Produced
Chloride
Acidify with dilute nitric acid, Then
(Cl-1)
add aqueous SILVER NITRATE
Bromide
Acidify with dilute nitric acid, Then
(Br-1)
add aqueous SILVER NITRATE
Iodide
Acidify with dilute nitric acid, Then
(I-1)
add aqueous SILVER NITRATE
Sulfate
Acidify, Then add aqueous BARIUM
(SO4-2)
NITRATE
White ppt
Sulfite
Add Dilute hydrochloric acid, warm
Sulfur dioxide produced
(SO3-2)
gently
Nitrate
Add aqueous Sodium Hydroxide, then
(NO3-1)
Aluminum; warm carefully
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White ppt
Creamy ppt
Yellow ppt
Ammonia produced
3 Test for gases
Gas
Test
Result
Ammonia
Damp Red Litmus paper
Turns blue
Chlorine
Damp litmus paper
Bleaches
Hydrogen
Lighted splint
Pops
Oxygen
Glowing splint
Relights
Acidified aqueous potassium
Turns from purple to
Sulfur Dioxide
manganate (VII)
colorless
Carbon Dioxide
Limewater
Turns milky
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4 Test for water:
Anhydrous copper sulfate:
White to blue
Anhydrous cobalt chloride:
Blue to pink
5 Flame Tests for Metal Ions
• Sodium: Yellow
• Copper: Blue green
• Lithium: red
• Potassium: Lilac
6 Drying Agents:
1 Sulfuric acid: for all gases except Ammonia
2 Calcium Oxide: for drying Ammonia
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Question 4 Plan an Investigation:
-Some Tips: 1 In Measuring Volume of Gas: Use Gas Syringe
2 In Measuring Mass: Use A balance
3 In High Temperature Reactions: Use A crucible
4 In Temperature change Reactions: Use A polystyrene Cup
5 In Colors: Use Chromatography
6 In Large Lumps: Crush Using Mortar and Pestle
-Most Repeated ideas in the Previous exams:
1 find out how the temperature Affect rate of Reaction? as in (june2021 V1)
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2 Calculate the Mass of Substance, as in (June 2021 V2)
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3 Which Substance produce the most energy (EXOTHERMIC REACTION) as in
(june2021 V3)
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4 Chromatography questions to know if a substance contains another substance
or not as in (NOV2021 V1)
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5 Displacement Reactions Between Metals As in (NOV 2021 V2)
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6 Determine the Concentration of Alkaline Solution As in (June2021 V2)
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7 Rusting Questions as in (June 19 V1):
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8 Determine which Metal is most reactive as in (June 2020 V1)
1 Put Each Metal in a beaker and put same volume of HCl in the 3 beakers
2 Put same concentration of HCL, and same masses of metals (for a fair test)
3 start timing when Solid added
4 Set the timer for 5 Minutes
5 stop the timer after 5 minutes
6 Calculate the volume of gas produced in the 5 minutes by Gas syringe
7 the metal that produce more volume of Gas is the Most reactive
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9 Solubility Questions as in (Nov 2020 V1)
The More You Solve the More you achieve!
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Thankful for Doctor Nouran Rostom!
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