Mass to Mass Conversion Problems Answer Key (CHEM 1405)

Back to Chemistry 1405 Practice Problems

Balance the equations, then solve for the required substance using dimensional analysis.

1. If 20.0 g of zinc reacts with hydrochloric acid, how many grams of zinc chloride are produced?

Zn(s) + 2HCl(aq) ZnCl₂(aq) + H₂(g)

$LaTeX: 20.0gZn\times(\frac{1molZn}{65.39gZn})\times(\frac{1molZnCl_2}{1molZn})\times(\frac{136.29gZnCl_2}{1molZnCl_2})=$ $20.0gZn\times(\frac{1molZn}{65.39gZn})\times(\frac{1molZnCl_2}{1molZn})\times(\frac{136.29gZnCl_2}{1molZnCl_2})=$ 41.7g ZnCl₂

2. How many grams of chlorine gas must react with sodium iodide to in order to produce 17.2 g of sodium chloride?

2NaI(s) + Cl₂(g) 2NaCl(s) + I₂(s)

$LaTeX: 17.2gNaCl\times(\frac{1molNaCl}{58.44gNaCl})\times(\frac{1molCl_2}{2molNaCl})\times(\frac{70.90gCl_2}{1molCl_2})=$ $17.2gNaCl\times(\frac{1molNaCl}{58.44gNaCl})\times(\frac{1molCl_2}{2molNaCl})\times(\frac{70.90gCl_2}{1molCl_2})=$ 10.4g Cl₂

3. How many grams of pure oxygen are produced in the decomposition of 5.50 grams of potassium chlorate?

2KClO₃(s) 2KCl(s) + 3O₂(g)

$LaTeX: 5.50gKClO_3\times(\frac{1molKClO_3}{122.55gKClO_3})\times(\frac{3molO_2}{2molKClO_3})\times(\frac{32.00gO_2}{1molO_2})=$ $5.50gKClO_3\times(\frac{1molKClO_3}{122.55gKClO_3})\times(\frac{3molO_2}{2molKClO_3})\times(\frac{32.00gO_2}{1molO_2})=$ 2.15g O₂

4. How many grams of copper are required to react with 4.00 grams of silver nitrate?

Cu(s) + 2AgNO₃(aq) Cu(NO₃)₂(aq) + 2Ag(s)

$LaTeX: 4.00gAgNO_3\times(\frac{1molAgNO_3}{169.88gAgNO_3})\times(\frac{1molCu}{2molAgNO_3})\times(\frac{63.55gCu}{1molCu})=$ $4.00gAgNO_3\times(\frac{1molAgNO_3}{169.88gAgNO_3})\times(\frac{1molCu}{2molAgNO_3})\times(\frac{63.55gCu}{1molCu})=$ 0.748g Cu

5. If ammonium sulfate reacts with 22.5 grams of calcium hydroxide, how many grams of ammonia (NH₃) are produced?

(NH₄)₂SO₄(aq) + Ca(OH)₂(aq) 2NH₃(g) + CaSO₄(aq) + 2H₂O(l)

$LaTeX: 22.5gCa(OH)_2\times(\frac{1molCa(OH)_2}{74.10gCa(OH)_2})\times(\frac{2molNH_3}{1molCa(OH)_2})\times(\frac{17.04gNH_3}{1molNH_3})=$ $22.5gCa(OH)_2\times(\frac{1molCa(OH)_2}{74.10gCa(OH)_2})\times(\frac{2molNH_3}{1molCa(OH)_2})\times(\frac{17.04gNH_3}{1molNH_3})=$ 10.3g NH₃

6. If sulfuric acid reacts with 36.2 grams of sodium chloride, how many grams of hydrochloric acid are produced?

2NaCl(aq) + H₂SO₄(aq) 2HCl(aq) + Na₂SO₄(aq)

$LaTeX: 36.2gNaCl\times(\frac{1molNaCl}{58.44gNaCl})\times(\frac{2molHCl}{2molNaCl})\times(\frac{36.46gHCl}{1molHCl})=$ $36.2gNaCl\times(\frac{1molNaCl}{58.44gNaCl})\times(\frac{2molHCl}{2molNaCl})\times(\frac{36.46gHCl}{1molHCl})=$ 22.6g HCl

7. How many grams of silver phosphate are produced if 11.9 grams of silver acetate reacts with sodium phosphate?

3AgC₂H₃O₂(aq) + Na₃PO₄(aq) Ag₃PO₄(s) + 3NaC₂H₃O₂(aq)

$LaTeX: 11.9gAgC_2H_3O_2\times(\frac{1molAgC_2H_3O_2}{166.92gAgC_2H_3O_2})\times(\frac{1molAg_3PO_4}{3molAgC_2H_3O_2})\times(\frac{418.58gAg_3PO_4}{1molAg_3PO_4})=$ $11.9gAgC_2H_3O_2\times(\frac{1molAgC_2H_3O_2}{166.92gAgC_2H_3O_2})\times(\frac{1molAg_3PO_4}{3molAgC_2H_3O_2})\times(\frac{418.58gAg_3PO_4}{1molAg_3PO_4})=$ 9.95 Ag₃PO₄

8. Consider the following reaction:

2NaOH(aq) + H₂SO₄(aq) 2H₂O(l) + Na₂SO₄(aq)

a) How many grams of sodium hydroxide are needed to completely neutralize 25.0 grams of sulfuric acid?

$LaTeX: 25.0gH_2SO_4\times(\frac{1molH_2SO_4}{98.08gH_2SO_4})\times(\frac{2molNaOH}{1molH_2SO_4})\times(\frac{40.00gNaOH}{1molNaOH})=$ $25.0gH_2SO_4\times(\frac{1molH_2SO_4}{98.08gH_2SO_4})\times(\frac{2molNaOH}{1molH_2SO_4})\times(\frac{40.00gNaOH}{1molNaOH})=$ 20.4g NaOH

b) If 43.6 grams of sodium sulfate are produced, how many grams of sodium hydroxide are needed?

$LaTeX: 43.6gNa_2SO_4\times(\frac{1molNa_2SO_4}{142.05gNa_2SO_4})\times(\frac{2molNaOH}{1molNa_2SO_4})\times(\frac{40.00gNaOH}{1molNaOH})=$ $43.6gNa_2SO_4\times(\frac{1molNa_2SO_4}{142.05gNa_2SO_4})\times(\frac{2molNaOH}{1molNa_2SO_4})\times(\frac{40.00gNaOH}{1molNaOH})=$ 24.6g NaOH

9. Consider the following reaction:

MnO₂(s) + 4HCl(aq) MnCl₂(aq) + 2H₂O(l) + Cl₂(g)

a) Calculate the mass of MnO₂ needed to produce 25.0 grams of water.

$LaTeX: 25.0gH_2O\times(\frac{1molH_2O}{18.02gH_2O})\times(\frac{1molMnO_2}{2molH_2O})\times(\frac{86.94gMnO_2}{1molMnO_2})=$ $25.0gH_2O\times(\frac{1molH_2O}{18.02gH_2O})\times(\frac{1molMnO_2}{2molH_2O})\times(\frac{86.94gMnO_2}{1molMnO_2})=$ 60.3g MnO₂

b) What mass of MnCl₂ is produced when 0.091 grams of chlorine gas is generated?

$LaTeX: 0.091gCl_2\times(\frac{1molCl_2}{70.90gCl_2})\times(\frac{1molMnCl_2}{1molCl_2})\times(\frac{125.84gMnCl_2}{1molMnCl_2})=$ $0.091gCl_2\times(\frac{1molCl_2}{70.90gCl_2})\times(\frac{1molMnCl_2}{1molCl_2})\times(\frac{125.84gMnCl_2}{1molMnCl_2})=$ 0.16g MnCl₂

c) How many grams of hydrochloric acid is needed to produce 31.66 grams of MnCl₂?

$LaTeX: 31.66gMnCl_2\times(\frac{1molMnCl_2}{125.84gMnCl_2})\times(\frac{4molHCl}{1molMnCl_2})\times(\frac{36.46gHCl}{1molHCl})=$ $31.66gMnCl_2\times(\frac{1molMnCl_2}{125.84gMnCl_2})\times(\frac{4molHCl}{1molMnCl_2})\times(\frac{36.46gHCl}{1molHCl})=$ 36.69g HCl