Practice Grams (Mass) in Chemistry
Use these practice problems to test your method after reviewing the concept explanation and worked examples.
Quick Recap
Grams are the base unit of mass in the metric system, measuring the quantity of matter in a substance. In chemistry, grams are the measurable quantity on a balance, but must be converted to moles for stoichiometric calculations using molar mass.
Grams tell you how heavy something is. A paperclip is about 1 gram. Moles tell you how many particles you have—a completely different question.
Example 1
easyConvert 2.50 moles of sodium chloride (NaCl) to grams. (Molar mass of NaCl = 58.44\,\text{g/mol})
Example 2
mediumHow many moles are in 49.0 g of sulfuric acid (\text{H}_2\text{SO}_4)? How many molecules does this represent? (Molar mass = 98.09\,\text{g/mol})
Example 3
mediumWhat mass in grams of iron is needed to provide 2.00 \times 10^{24} atoms of iron? (Fe = 55.85\,\text{g/mol})
Example 4
hardIn the reaction 2\text{Al} + 3\text{Cl}_2 \rightarrow 2\text{AlCl}_3, calculate the mass in grams of \text{AlCl}_3 produced from 13.5 g of aluminum reacting with excess chlorine. (Al = 26.98, Cl = 35.45\,\text{g/mol})