1. Perform the following calculations following the rules of significant figures
a. (64.2 m × 4.750 m × 0.00095 m) / 4.2 m
b. (27.2 m + 4.250 m + 0.00095 m) – 3.413 m
c. (6.15 mL + 8.17 mL) × 8 mL
2. Convert the following masses into number of moles
a. 95.7 kg of NaOH
b. 38.02 g NaHCO3
3. Diamond is a natural form of pure carbon.
a. How many moles of carbon are in 1.5-carat diamond (1 carat = 0.200 g)?
b. How many atoms of carbon are in the diamond?
4. A sample of the male sex hormone testosterone, C19H28O2, contains 4.18 x 1021 atoms of
hydrogen.
a. How many atoms of carbon does it contain?
b. How many molecules of testosterone does it contain?
c. How many moles of testosterone does it contain?
d. What is the mass of the sample in gram?
5. Calculate the percentage by mass of the indicated element in the following compounds:
a. Carbon in acetylene, C2H2, a gas used in welding;
b. Hydrogen in ammonium sulfate, (NH4)2SO4, a substance used as a nitrogen fertilizer;
c. Oxygen in ascorbic acid, HC6H7O6, also known as vitamin C
6. Calculate the mass of CO2 produced from the complete combustion of 30.0 tonnes of ethyne,
C2H2.
2C2H2 (g) + 5O2 (g) ? 4CO2 (g) + 2H2O (l)
7. Sodium hydroxide reacts with carbon dioxide as follows: 2NaOH(s) + CO2(g) ?Na2CO3(s)
+ H2O(l)
a. Which reagent is the limiting reactant with 1.70 mol NaOH and 1.00 mol CO2 are
allowed to react?
b. How many moles of Na2CO3 can be produced?
c. How many moles of the excess reactant remain after the completion of the reaction?
8. Consider the reaction below:
Fe2O3 (s) + 3CO (g) ? 2Fe (l) + CO2 (g)
a. If you start with 150 g of iron as the limiting reagent, what is the theoretical yield of
iron, Fe?
b. If the actual yield of iron is 67.9 g, what was the % yield of iron?
9. A solution of sodium hydroxide contained 0.25 moldm-3. Titration of 25.0 cm3 of this
solution required 22.5cm3 of a HCl solution for complete neutralization.
HCl (aq) + NaOH (aq) ? NaCl (aq) + H2O (l)
a. Calculate the moles of sodium hydroxide neutralized
b. Calculate the moles of HCl neutralized.
c. Calculate the concentration of the HCl in mol/dm3 (molarity).