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WorksheetsMoles and Molar Mass and Percent Composition Review
Total questions: 36
Worksheet time: 3hrs 33mins
Calculate the molar mass of H2O.
18.015 g/mol
12.011 g/mol
20.015 g/mol
36.031 g/mol
Find the molar mass of CO2.
36.02 g/mol
44.01 g/mol
22.01 g/mol
50.03 g/mol
Determine the percent composition of water (H2O).
20% hydrogen and 80% oxygen
30% hydrogen and 70% carbon
11.19% hydrogen and 88.81% oxygen
10% hydrogen and 90% nitrogen
Calculate the percent composition of carbon dioxide (CO2).
27.3% carbon, 72.7% oxygen
10% carbon, 90% oxygen
50% carbon, 50% oxygen
40% carbon, 60% oxygen
Convert 5 moles of NaCl to grams.
10.5 grams
500 grams
1000 grams
292.2 grams
Convert 10 grams of H2O to moles.
0.010 moles
1.25 moles
0.555 moles
5.55 moles
Use Avogadro's number to calculate the number of atoms in 2 moles of O2.
2 x 6.022 x 10^24 = 1.2044 x 10^25 atoms of O2
2 x 6.022 x 10^22 = 1.2044 x 10^23 atoms of O2
2 x 6.022 x 10^23 = 1.2044 x 10^24 atoms of O2
2 x 6.022 x 10^21 = 1.2044 x 10^22 atoms of O2
How many molecules are present in 3 grams of H2O?
9 x 10^23 molecules
1.8 x 10^23 molecules
6 x 10^23 molecules
3 x 10^23 molecules
If the molar mass of a compound is 180 g/mol, how many moles are present in 360 grams?
0.5 moles
2 moles
360 moles
180 moles
Solve a problem involving the empirical formula of a compound.
Find the molar mass of the compound and divide by the number of atoms.
Determine the mass of each element, convert to moles, find the ratio, and simplify to get the empirical formula.
Use the ideal gas law to calculate the empirical formula.
Count the number of atoms in the compound.
Mia and Oliver are studying for their chemistry exam. They come across a question about a mineral they found during their field trip. The mineral is CaF2 (gram-formula mass = 78 g/mol). They want to know the percent by mass of fluorine in this mineral. Can you help them calculate this?
24%
49%
51%
65%
How many grams are in 1.2 moles of Neon?
0.05 grams
16.6 grams
21.2 grams
24 grams
Daniel has 4.3 x 1024 molecules of H2O in his science project. How many moles does this represent?
6.02 x 1023
7.14
18.02
128.66
How many bananas are there in 3.5 moles of bananas?
3.5
3.5 x 6 x 1023
35 / 6 x 1023
What is the percentage of OH- in Ca(OH)2?
45.9%
75%
66.6%
90.1%
Abigail is working on a science project and needs to calculate the mass of sulfur hexafluoride she would have if she had 2.5 moles of it. Can you help her figure it out?
250 g
300 g
145 g
78 g
Abigail, Elijah, and Oliver are working on a science project. They have 425.0 g of sodium chloride. Can you help them figure out how many moles of sodium chloride they have?
9.835 mol
8.126 mol
7.272 mol
6.691 mol
Abigail, Lily, and Sophia are working on a chemistry project where they need to determine the gram formula mass of Silicon Tetrabromide. Can you help them find it?
107.99 g/mol
347.70 g/mol
187.89 g/mol
267.80 g/mol
What is the molecular weight of iron (III) nitrate?
145.847 g/mol
117.854 g/mol
241.8 g/mol
85.854 g/mol
Abigail, James, and Aiden are working on a chemistry project. They need to calculate the molar mass of potassium phosphate for their experiment. Can you help them find out the molar mass of potassium phosphate?
212.27 g
251.37 g
86.07 g
173.17 g
196.27 g
Arjun, Nora, and Abigail are studying chemistry together. They are trying to calculate the mass % of H in methane (CH4). They come up with different answers. Can you help them find the correct answer?
75%
92%
25%
4%
6%
Samuel, Benjamin, and James are working on a science project where they need to convert 25 grams of CO2 they produced into total atoms. How many formulas would they use to do this conversion?
One
Two
Three
More than I can imagine. Perhaps to infinity and beyond.
Abigail, Maya, and Priya are working on a science project. They found a sample that contains 8.65 x 1025 atoms of arsenic. Can you help them figure out how many grams of arsenic are in their sample?
9,220 g As
10,765 g As
6,889 g As
None of these
A mole is equal to (check ALL that apply):
6.02 x 1023 atoms/molecules/particles
22.4 L of any gas at STP
The molar mass of any element or compound
3.14 x 1024 atomic mass units
Noah, Luna, and Mia are working on a chemistry project. They need to calculate the molar mass of Mg(C2H3O2)2. Can you help them?
142.3 g/mol
154.3 g/mol
162.3 g/mol
178.3 g/mol
A mole of Ar gas is equal to (check ALL that apply):
22.4 L
6.02 x 10^23 atoms
39.95 grams
17.85 grams
Emma, Aria, and Oliver are working on a chemistry project. They need to calculate the percent composition of each element in a sample of CaCO3. Can you help them?
Ca = 40%, C = 12%, O = 48%
Ca = 20%, C = 30%, O = 50%
Ca = 50%, C = 20%, O = 30%
Ca = 30%, C = 40%, O = 30%
You are a beginner chemistry student who is just starting to get comfortable with a calculator. You calculate the molar mass of NaCl to be 60 g/mol. What is the percent error of your calculation?
15.4%
23.5%
30.2%
Mason, Samuel, and Ava are working on a chemistry project related to the manufacturing of aluminum fluoride (AlF3) used in the production of aluminum. They have produced 0.320 moles of AlF3 and need to find out how many fluorine ions are present in it. Can you help them?
1.93 x 1023 ions
5.78 x 1023 ions
6.42 x 1022 ions
3.85 x 1023 ions
Emma, Aria, and Oliver are working on a chemistry project. They need to calculate the molar mass of sodium sulfate for their experiment. Can you help them find out the molar mass of sodium sulfate?
142.04 g/mol
132.14 g/mol
142.14 g/mol
152.14 g/mol
Abigail, Elijah, and Oliver are working on a science project. They have 500.0 g of potassium chloride. Can you help them figure out how many moles of potassium chloride they have?
6.72 mol
7.14 mol
6.02 mol
5.55 mol
Mason, Samuel, and Ava are working on a chemistry project related to the manufacturing of magnesium chloride (MgCl2) used in the production of magnesium. They have produced 0.500 moles of MgCl2 and need to find out how many chloride ions are present in it. Can you help them?
3.01 x 1023 ions
6.02 x 1023 ions
1.20 x 1024 ions
2.40 x 1024 ions
Calculate the molar mass of NaOH.
39.997 g/mol
58.443 g/mol
18.015 g/mol
60.052 g/mol
Abigail, Elijah, and Oliver are working on a science project. They have 250.0 g of calcium chloride. Can you help them figure out how many moles of calcium chloride they have?
2.23 mol
3.14 mol
1.78 mol
4.02 mol
Emma, Aria, and Oliver are working on a chemistry project. They need to calculate the percent composition of each element in a sample of Na2CO3. Can you help them?
Na = 43.38%, C = 11.33%, O = 45.29%
Na = 30%, C = 20%, O = 50%
Na = 50%, C = 20%, O = 30%
Na = 20%, C = 40%, O = 40%
