2014
[LABORATORY MANUAL]
Lab instructions and recod keepingfor lab activities and mixed reception mystery
TABLE OF CONTENTS
Laboratory Manual
Monday Afternoon: Flame test for
identifying unknowns
Page 2
Tuesday Afternoon: Gases and
Breathing
Page 3
Wednesday Afternoon: Density of
solids/ how to count by mass.
Page 5
Thursday Lab – Unknown solids
Page 7
Friday- Properties of common liquids
Page 8
Mixed Reception Worksheet
Page 9
Mixed Reception Final Report
Page 13
Page 1
Monday Afternoon: Flame test for identifying unknowns
Flame can be used to excite a metal or metalloid, causing it emit light characteristic of the energy of the
excitement specific to the element or ion.
It can be done by dipping a clean metal loop into a powder or solution of the material or by soaking a
splint or swab in the material and passing it through a flame.
In this lab, will observe the flame colors with 4 different materials, then based on our observations; try
to determine the identity of an unknown.
1. Calcium, Ca2+ (from 0.1 M Ca(NO3)2)
2. Strontium, Sr2+ From )
3. Sodium, Na+ (from 0.1 M NaCl)
Unknown ID
Student
Color
observation
Flame Test Colors from literature
Symbol Element
Color
As
Arsenic
Blue
Ca
Calcium
Orange to red
Cs
Cesium
Blue
Cu(I
Copper(I)
Blue
Cu(II) Copper(II) non-halide Green
Cu(II) Copper(II) halide
Blue-green
Fe
Iron
Gold
K
Potassium
Lilac to red
Li
Lithium
Magenta to carmine
Mg
Magnesium
Bright white
Mn(II) Manganese(II)
Yellowish green
Mo
Molybdenum
Yellowish green
Na
Sodium
Intense yellow
P
Phosphorus
Pale bluish green
Pb
Lead
Blue
Rb
Rubidium
Red to purple-red
Sb
Antimony
Pale green
Se
Selenium
Azure blue
Sr
Strontium
Crimson
Te
Tellurium
Pale green
Tl
Thallium
Pure green
Page 2
Identification
Tuesday Afternoon: Gases and Breathing
Every normal thing around us can be explained by laws of chemistry and physics. For example, the gas
law relates pressure, volume, amount of molecules, and temperature to each other by this equation
PV=nRT
Or
Pressure (P) x Volume (V)= number of molecules (n) x the gas constant(R) x temperature in Kelvin(T)
Introduction
Inhale. Exhale. Breathing is automatic. But how do we breathe? The breathing process can be explained
by applying gas laws, specifically the pressure-volume relationship. In this lab, you will simulate the
breathing process with a syringe serving as your lungs and the syringe piston as your diaphragm. Using a
fixed amount of gas, you will vary the volume and measure the resulting pressure of gas.
Materials
syringe, Vernier pressure sensor, LabPro, computer
Procedure
Pressure-volume relationship of a gas.
Using a fixed amount and temperature of gas, you will vary the volume and measure the resulting
pressure of gas.
1. The Vernier pressure sensor will be connected to a computer and the computer set up to record
pressure in the unit of “Atmospheres”
2. To set up your experiment, click on the data collection button (this button has a graph on it)
immediately left of the “Collect” button on the upper right side. In the dialog box that appears, enter the
following options:





Mode: Events with Entry
Column Name: Volume
Short Name: V
Units: ml
Then click “Done”.
c. Move the piston of the 20 ml syringe to the 10.0 ml mark. Attach the 20 ml syringe to the
white stem at the end of the pressure sensor box with a gentle half turn. This seals in the air that it
inside and from this point forward, the number of molecules inside the syringe is constant.
2. Mimic the breathing process with the syringe as your lungs and the piston as the diaphragm.
a. When you inhale, what happens to your diaphragm? Do this with the syringe and piston.
What happens to the volume of your lungs/syringe? How does this change in volume affect the
pressure? Does this pressure change correspond to what happens inside your lungs? Explain how
air gets into your lungs based on this pressure change.
b. When you exhale, what happens to your diaphragm? Do this with the syringe and piston.
What happens to the volume of your lungs/syringe? How does this change in volume affect the
pressure? Does this pressure change correspond to what happens inside your lungs? Explain how
air leaves your lungs based on this pressure change.
3. a. Click the “Collect” button to start collecting data. Move the piston in the syringe to the 5.0
ml mark. Hold the piston in this position until the pressure reading stabilizes. When the pressure is
stable, write down the reading in atmospheres to 2 decimal places (eg 1.27) on Table 1.
Page 3
b. Repeat for volumes 7.5 ml, 10.0 ml, 12.5 ml, 15.0 ml, 17.5 ml, and 20.0 ml.
Table 1
Volume (ml)
Pressure (atm)
Inverse of
pressure (1/atm)
5.0
7.5
10.0
12.5
17.5
20.0
c. Click the “Stop” button when you have finished collecting data.
4. Plot the data by hand on the graphs above. Which one is linear? Does your graph make sense in light
of the following?
With number of moles and temp constant, the equation simplifies to
PV= constant
Or
V=1/P x constant
Demonstration:
Increasing the number of moles of gas
Dry Ice is frozen CO2. As it Sublimes, the solid turns to gas, in a sealed container more gas in the same
volume is expected to do what to the pressure Where the volume is not held constant (balloon
receiver), what is expected to happen to the volume.
In the first case, the constants are R (the gas constant), V (the volume in the flask) and T (consider dry
ice temp negligible with no insulation) so the equation becomes
P=n x constant
In the second case, the constants are R (the gas constant), P (the atmospheric pressure) and T (consider
dry ice temp negligible with no insulation) so the equation becomes
V=n x constant
Page 4
Wednesday Afternoon: Density of solids/ how to count by mass.
Lab 2. Properties of Substances: Density
KEY POINTS:
1. Properties, such as density, are used to identify substances and distinguish between
substances.
2. Density is the ratio of mass to volume. Measure mass and volume to calculate density.
3. Use significant figures in measurements and calculations.
Introduction
How do you identify one person from another? Each person has unique characteristics or properties,
such as name, height, weight, hair color, etc. We do the same thing with substances. Substances are
characterized by properties which are used to identify substances. In the first part of this lab, you will
observe the properties of various elements and identify a property that the metal elements have in
common and a property that the non-metal elements have in common. Next, you will mass and volume
observations of common objects and use these observations to describe and distinguish different
substances from each other. However, the mass and volume of two different substances could be the
same. For example, a baseball and tennis ball has approximately the same volume. One baseball and
several tennis balls have the same mass. So, mass and volume are not enough.
You will relate the mass and volume of a substance to its density:
density = mass/volume
and use this property to distinguish between different substances.
Materials
Copper, tin, lead, aluminum, silver, nickel, carbon (graphite), silicon, pennies.
Measure the density of a solid using the displacement method. Your instructor will assign you
to measure the density of a:
(i) solid metal element,
(ii) solid non-metal element, and
(iii) unknown solid
For each solid,
a. Measure the mass. The solid should be clean and dry.
b. Fill a graduated cylinder approximately half-full with water. Record the volume of the water.
c. Carefully place the solid into the graduated cylinder containing the water. You may want to tilt
the graduated cylinder and slide the solid down to the bottom of the cylinder. The volume of
water displaced by the solid object equals the volume of the solid object.
d. Record the volume of the water and solid.
e. Calculate the density of the solid.
f. Determine the identity of the unknown solid.
Page 5
data table
element element element element
1
2
3
4
identity
mass (grams)
volume in graduated
cylinder before adding
element( ml)
volume after adding
element (ml)
volume of the
element(ml)
density (g/ml)
2. Guess the bank.
Each group should devise a method to estimate the value of the piggy
bank by weight.
Fact: the piggy bank weighs exactly _________ g empty (given by
instructor)
A sample of pennies is counted and weighed by each group
Number of pennies_____________
Weight_______________________
Mass of each penny____________ (calculated)
Each group determines the mass of the bank. (Scale for bank
measures in pounds)
Mass of bank with pennies___________________lbs
Mass of bank with pennies ___________________g (calculated)
The Composition of the
Cent
Following is a brief chronology of the metal
composition of the cent coin (penny):
The composition was pure copper from
1793 to 1837.
From 1837 to 1857, the cent was made of
bronze (95 percent copper, and five percent
tin and zinc).
From 1857, the cent was 88 percent copper
and 12 percent nickel, giving the coin a
whitish appearance.
The cent was again bronze (95 percent
copper, and five percent tin and zinc) from
1864 to 1962.
(Note: In 1943, the coin's composition was
changed to zinc-coated steel. This change
was only for the year 1943 and was due to
the critical use of copper for the war effort.
However, a limited number of copper
pennies were minted that year.
In 1962, the cent's tin content, which was
quite small, was removed. That made the
metal composition of the cent 95 percent
copper and 5 percent zinc.
The alloy remained 95 percent copper and
5 percent zinc until 1982, when the
composition was changed to 97.5 percent
zinc and 2.5 percent copper (copper-plated
zinc). Cents of both compositions appeared
in that year.
Convert pounds to grams and subtract starting weight for weight of pennies in bank. Write your guess
with your name on the board. The correct number of pennies wins the bank!
3. Dissolve the inside of a Penny- Start today to complete Friday.
File off the outer edge of your penny, record the year ________
Record the weight of the penny using a scale that measures to two decimal places (to 1/100 of a gram or
0.00 g when zeroed) _______ g. Place penny in a 50 ml beaker with your name on it and cover with a
watchglass.
Friday: Weigh the remaining parts of the penny________(copper remains). What percentage of the
penny disappeared?_____________________
Page 6
Thursday Lab – Unknown solids
Lab Activity for Science Academy: Identification of white solids
You are working for a large baking operation. There was a flood in the storage area and several labels
washed off the 50 gallon drums of some of the baking ingredients. Your task is to figure out what was in
the barrels.
Here are the labels that were found on the floor: sugar; baking soda; white flour; salt. Using your
problem solving skills, how can you easily and quickly discover what each drum contains?
You will be giving known samples of each of the ingredients in small containers labeled with the name of
the ingredient. You will also have access to samples of each of the barrels. They are marked with
assigned numbers. Can you match each of the barrels with their correct name?
Hints: (instructor can provide these clues if necessary)
Barrel
Identity
Page 7
Density (how
heavy or light is
one scoop of the
material)
Solubility (does
the material
dissolve in water
or IPA?)
Color and
appearance (does
the material look
like one of the
others?)
Reaction with
vinegar (only
baking soda will
react)
Friday- Properties of common liquids
1. pH indicator in Cabbage juice
Make your own pH indicator solution! Red cabbage juice contains a natural pH indicator that changes
colors according to the acidity of the solution. Red cabbage juice indicator is easy to make, exhibits a
wide range of colors, and can be used to make your own pH paper strips.
Introduction
Red cabbage contains a pigment molecule called flavin (an anthocyanin). This water-soluble pigment
is also found in apple skin, plums, poppies, cornflowers, and grapes. Very acidic solutions will turn
anthocyanin a red color. Neutral solutions result in a purplish color. Basic solutions appear in greenishyellow. Therefore, it is possible to determine the pH of a solution based on the color it turns the
anthocyanin pigments in red cabbage juice.The color of the juice changes in response to changes in its
hydrogen ion concentration. pH is the -log[H+]. Acids will donate hydrogen ions in an aqueous
solution and have a low pH (pH 7).
In this lab, the cabbage juice indicator was made for you by the procedure below, which is included in
case you ever want to repeat at home!
Materials
 red cabbage
 blender or knife




boiling water
filter paper (coffee filters work well)
One large glass beaker or other glass container
beakers or other small glass containers
Procedure
1. Chop the cabbage into small pieces until you have about 2 cups of chopped cabbage. Place the cabbage in a large beaker or
other glass container and add boiling water to cover the cabbage. Allow at least ten minutes for the color to leach out of the
cabbage. (Alternatively, you can place about 2 cups of cabbage in a blender, cover it with boiling water, and blend it.
2.
Filter out the plant material to obtain a red-purple-bluish colored liquid. This liquid is at about pH 7. (The exact color you
get depends on the pH of the water.)
3.
4.
Pour resulting solution into 250 mL beakers or jars.
Put a small amount (about 1 ml) of each solution to be tested in a test tube, add cabbage solution until you see a color
change.
Studenttyping
observations
Page 8
Substance
color
Approximate pH
Mixed Reception Worksheet
Each group has one worksheet, so work on them together. Take notes on them and use them to
help you solve the problem. We are going to collect them, but the task at hand is solving a
murder, not filling out a worksheet.
While you watch the introduction video, note below your preliminary thoughts about which
person/people you personally suspect, and why & how they might have done it.
Page 9
While you interview suspects and gather evidence, make notes below about each suspect –
do you personally suspect them? What reasons might they have had to commit the crime, and
most importantly, how might they have done it? What were their means?
Do you suspect this person?
What is their motive?
How might they have done it?
Dr Yervin
Do you suspect this person?
What is their motive?
How might they have done it?
Sam
Do you suspect this person?
What is their motive?
How might they have done it?
Joanna
Do you suspect this person?
What is their motive?
How might they have done it?
Vince
Do you suspect this person?
What is their motive?
How might they have done it?
Nelson
Page 10
While you gather evidence, make notes below about how each piece of evidence might relate
to a suspect, how it might have been used in the crime, etc.
Drug Info
Sheet
Joanna’s
Emails
Anti-Toxin
Report
Punch
Coroner’s
Report
Nelson’s
Journal
Peanuts
Peanut Pie
Nelson’s Pills
Page 11
Pills from
Joanna’s
Office
Use this page for additional notes, calculations, and conclusions you make as you analyze the
evidence and form your conclusion.
When you’re ready to report your findings, call a teacher over. They’ll interview you as you
report the cause of death, the guilty party, and the evidence that lead you to your findings.
Page 12
Case Report Form
Group number __________________
An unknown substance was present in Nelson’s blood. What was this substance and how did it get into
his blood? What evidence do you have to support this?
The molecular weight of the unknown substance in Nelson’s blood is 765.82? Why?
What is the MW of the allergy drug?
What is the MW of the anti-venom?
The coroner says that Nelson died from peanut allergy, yet he was taking a drug for this. Can you explain
why he would still die from peanuts?
Did Nelson take his medication that day? Was the correct concentration of medication present in his
blood?
You found an abstract on Sam’s desk. Is this evidence relevant to your solution? Why or why not?
How did Sam know that giving Nelson the antivenom would kill him?
There were pills found in Joanna’s office. Is this evidence relevant to your solution? Why or why not?
Page 13
Are Joanna’s emails important evidence in support of your solution?
Was any of the food left at the crime-sceen important evidence for your case? Why or why not?
Who did it?
Why did they do it?
How did they do it?
Page 14