Mole Quiz
Questions: 16 · 10 minutes
1. A compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?
CH₂O
CO₂
C₂H₄O₂
CHO
2. Approximately how many molecules are present in 0.50 mol of CO₂?
1.20 × 10²⁴ molecules
3.01 × 10²³ molecules
6.02 × 10²³ molecules
8.30 × 10⁻²⁵ molecules
3. How many moles of solute are present in 200 mL of a 0.50 mol/L solution?
0.025 mol
0.040 mol
0.100 mol
2.5 mol
4. Which quantity is known as Avogadro’s constant?
1.008 grams per mole
8.314 grams per liter
22.4 liters per mole under all conditions
6.02214076 × 10²³ per mole
5. Using H = 1.008 g/mol and O = 16.00 g/mol, what is the molar mass of H₂O?
17.01 g/mol
18.02 g/mol
32.00 g/mol
34.02 g/mol
6. A reaction has a theoretical yield of 10.0 g and produces 8.0 g. What is its percent yield?
80%
25%
125%
20%
7. Using PV = nRT with R = 0.0821 L·atm/(mol·K), what volume does 0.50 mol of an ideal gas occupy at 300 K and 2.0 atm?
3.08 L
12.3 L
6.16 L
24.6 L
8. In chemistry, what does one mole represent?
Exactly 1 × 10³ particles of a substance
The mass in grams of one atom of an element
The volume occupied by any substance at room temperature
Exactly 6.02214076 × 10²³ specified entities
9. Two ideal-gas samples have the same temperature, pressure, and volume. One contains nitrogen and the other contains oxygen. How do their numbers of molecules compare?
The oxygen sample has twice as many molecules because O₂ is heavier
They contain the same number of molecules
The nitrogen sample has more molecules because N₂ has a lower molar mass
Their numbers cannot be compared without knowing their masses
10. A sample contains 1.2044 × 10²⁴ helium atoms. Approximately how many moles of helium is this?
2.00 mol
1.00 mol
1.50 mol
0.50 mol
11. A water sample has a mass of 36.04 g. Given a molar mass of 18.02 g/mol, how many moles does it contain?
0.50 mol
649.4 mol
18.02 mol
2.00 mol
12. How much NaCl is needed to prepare 250 mL of a 0.200 mol/L solution? Use a molar mass of 58.44 g/mol.
5.84 g
2.92 g
11.69 g
46.75 g
13. A sample contains 44.0 g of CO₂, whose molar mass is about 44.0 g/mol. Approximately how many molecules are in the sample?
6.02 × 10²³ molecules
2.65 × 10²⁵ molecules
1.00 molecule
4.40 × 10²² molecules
14. The molar mass of NaCl is 58.44 g/mol. What is the mass of 0.250 mol of NaCl?
4.28 g
7.31 g
14.61 g
233.76 g
15. Assuming ideal behavior at 0°C and 1 atm, approximately how many moles of gas occupy 22.4 L?
22.4 mol
0.50 mol
2.00 mol
1.00 mol
16. For the reaction 2H₂ + O₂ → 2H₂O, 3.0 mol of H₂ is mixed with 2.0 mol of O₂. Which reactant limits the amount of water produced?
O₂, because it has fewer moles than the amount of H₂
Neither, because all gases have equal molar volumes
H₂, because 2.0 mol of O₂ would require 4.0 mol of H₂
H₂O, because it appears on the product side