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CHM 121 Relative Mass and the Mole Lab Report
- Course
- Chemistry 121
- Institution
- Harper College
This is a comprehensive and detailed lab report on; Mole and Relative Mass for Chm 121. *Essential!!
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Relative Mass and the MoleHow can atoms be counted using a balance?
Why?
Consider the following equation for a chemical reaction: 2H2 + O2 2H2O
This can be interpreted as two molecules of hydrogen and one molecule of oxygen combining to
form two water molecules. But how often do chemists limit their reactions to one or two molecules?
Usually a reaction is done with an unimaginable number of molecules. How then do chemists know
they have the right mix? The molecules need to be quickly counted! How do we count molecules?
The answer is the unit called the mole. This activity will start by considering two egg farmers (a
chicken farmer and a quail farmer). They produce such large numbers of eggs that they can’t count
them all individually, so they count in dozens of eggs in some cases, while in other cases they use
mass. Weighing is often easier than counting!
Model 1 – Eggs
Chicken Quail Ratio of Ratio of
numbers masses
of eggs of eggs
Number of eggs Mass of the Number of eggs Mass of the
in the sample sample in the sample sample
1 37.44 g 1 2.34 g 1: 1 16: 1
10 374.40 g 10 23.40g 1: 1 16: 1
438 16398.72g 438 1024.92g 1: 1 16: 1
1 dozen 449.28g 1 dozen 28.08g 1: 1 16: 1
1 million 37440000.00g 1 million 2340000.00g 1:1 16 : 1
1. Consider the data in Model 1.
a. What is the mass of a standard chicken egg?
37.44g
b. What is the mass of a standard quail egg?
2.34g
c. Show mathematically how the 16:1 ratio of masses was calculated in the last column of
Model 1.
Ratio of masses of eggs = mass of 1 chicken egg / mass of 1 quail egg
= 37.44g / 2.34g
=
= 16 : 1
2. Use a calculator to complete the table in Model 1. Divide the work among group
members. Reduce all ratios to the lowest whole numbers possible.
Relative Mass and the 1
, 3. Imagine you have two baskets—one filled with quail eggs and one filled with the same
number of chicken eggs.
a. Which basket would be heavier?
The basket filled with chicken eggs
b. How many times heavier would that basket be?
16 times heavier
c. Explain mathematically how it is possible for you to answer part b with confidence,
even though you don’t know the actual number of eggs.
16 : 1 – 1 chicken egg is 16 quail eggs
16qe / 1qe = 1ce / 1qe
16qe = 1ce
Therefore, for any number of eggs, the mass of chicken eggs is 16 times the mass
of quail eggs
4. A farmer weighs out 32.0 kg of chicken eggs.
a. What mass of quail eggs would he need to weigh out to have the same number of
eggs in both samples?
= 32.0kg / x
= 2.0kg of quail eggs
b. If the farmer had weighed out 32.0 pounds of chicken eggs (rather than kilograms),
what mass of quail eggs would he need to weigh out to have the same number of eggs
in both samples?
16 /1 = 32.0 pounds / x
= 2.0 pounds of quail eggs
5. A farmer makes up a new counting unit called a “cluckster.”
a. If the farmer had 3 clucksters of chicken eggs and 3 clucksters of quail eggs, what could
you say about the ratio of their masses?
The ratio will still be 16 : 1 since it is the same egg just different counting unit
b. Does it matter in this problem how many eggs are in a “cluckster”? Explain.
It does not matter the number of eggs in a cluster, the ratio will still be the same as long as it is the
same egg.
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