Mole Lab
Objective
In this lab we will measure the mass of five different chemicals. You will use this data to calculate the number of moles of each
chemical and the number of molecules or atoms of each chemical. By correctly completing this lab you should get some practice
doing mole conversion calculations, learn about relative numbers of molecules or atoms in different substances, and begin to see
how the chemical unit of the mole can be useful.
Materials
lab balance
lumps of aluminum (Al)
lumps of zinc (Zn)
sand (SiO2)
water (H2O)
sucrose sugar (C12H22O11)
weighing boat (plastic cup)
50-mL beaker
Safety
Lab goggles
Wash hands after touching chemicals
Part 1: Pre – Lab Questions (SHOW WORK)
1.
2.
Find the molar mass of each of the five substances listed in the materials section of this lab.
a.
b.
If you have 2.5 mol of H2O, how many grams is this?
How many molecules of H2O do you have?
3.
a.
b.
If you have 145.54 g of SiO2, how many moles is this?
How many molecules of SiO2 do you have?
a.
b.
If you have 2.107 × 1024 molecules of C12H22O11, how many moles is this?
How many grams of C12H22O11 do you have?
4.
You must get your prelab checked off BEFORE getting samples.
Part 2: Procedure
1.
Obtain samples of each substance from your teacher. Weigh each sample to the nearest 0.01 g and record mass in data
table 1. Also record the molar mass that you calculated for your prelab in data table 1.
Part 3: Lab Calculations and Analysis Questions (SHOW WORK)
Answer the following questions and perform the following calculations. Answers must be in complete sentences. Show work for all
calculations.
1. Before you do any calculations, which sample do you think has the largest number of atoms or molecules? Why?
2. Before you do any calculations, which sample do you think has the smallest number of atoms or molecules? Why?
3. Calculate the number of moles of each substance based on the mass you measured and record in data table 2. SHOW
WORK!
4. Calculate the number of molecules or atoms of each substance based on the number of moles you calculated and record in
data table 2. SHOW WORK!
5. Now that you have done the calculations, which sample had the largest number of atoms/molecules? Why?
6. Now that you have done the calculations, which sample had the smallest number of atoms/molecules? Why?
7. Which sample has a greater number of moles: 100. g of sodium hydroxide (NaOH) or 100. g of krypton gas (Kr)?
8. You have the same mass of both chemicals in the previous question. Why didn’t you get the same number of moles?
9. In order to react fully without leaving anything leftover every mole of oxygen gas (O2) must react with two moles of
hydrogen gas (H2):
2H2 + 1O2 --> 2H2O
If you have 64.00 g of O2 and 2.016 g of H2, Is there enough H2 to react with the O2 you have?
(Hint: Convert grams to moles before attempting to answer the question).
Data Table 1: Mass of 5 Substances
Name
Formula
Molar Mass (g/mol)
Mass (g)
Al
Zn
SiO2
H2O
sucrose
Formula
Data Table 2: Number of Moles of 5 Substances
Mass (g)
Moles
Atoms/Molecules
Al
Zn
SiO2
H2O
C12H22O11
Data Table 1: Mass of 5 Substances
Name
Formula
Molar Mass (g/mol)
Mass (g)
Al
Zn
SiO2
H2O
sucrose
Formula
Al
Zn
SiO2
H2O
C12H22O11
Data Table 2: Number of Moles of 5 Substances
Mass (g)
Moles
Atoms/Molecules