Mole Ratios and Mole Conversions Answer Key (CHEM 1405)

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Balance the following equations, and then write the mole ratios, using dimensional analysis.

1.     N₂     +    3H₂        2NH₃

 

a) write the ratio of nitrogen gas to hydrogen gas:  $\frac{1molN_2}{3molH_2}$ or $\frac{3molH_2}{1molN_2}$ 

 

b) nitrogen gas to ammonia (NH₃):   $\frac{1molN_2}{2molNH_3}$ or $\frac{2molNH_3}{1molN_2}$ 

 

c) hydrogen gas to ammonia (NH₃):   $\frac{3molH_2}{2molNH_3}$ or $\frac{2molNH_3}{3molH_2}$ 

 

 

 

2.     8H₂     +    S₈        8H₂S

 

a) hydrogen gas to hydrogen sulfide:  $\frac{8molH_2}{8molH_2S}$ or $\frac{8molH_2S}{8molH_2}$ (This ratio can be reduced to 1:1)

 

b) hydrogen gas to sulfur:  $\frac{8molH_2}{1molS_8}$ or $\frac{1molS_8}{8molH_2}$ 

 

c) hydrogen sulfide to sulfur:  $\frac{8molH_2S}{1molS_8}$ or $\frac{1molS_8}{8molH_2S}$ 

 

 

 

3.     CH₄     +     2O₂         CO₂    +     2H₂O

 

a) oxygen gas to carbon dioxide:  $\frac{2molO_2}{1molCO_2}$ or $\frac{1molCO_2}{2molO_2}$ 

 

b) methane (CH₄) to carbon dioxide:   $\frac{1molCH_4}{1molCO_2}$ or $\frac{1molCO_2}{1molCH_4}$ 

 

c) methane (CH₄) to water:   $\frac{1molCH_4}{2molH_2O}$ or $\frac{2molH_2O}{1molCH_4}$ 

 

d) oxygen gas to water:   $\frac{2molO_2}{2molH_2O}$ or $\frac{2molH_2O}{2molO_2}$ 

 

 

 

4.     2H₂     +    O₂         2H₂O

 

a) hydrogen gas to water:  $\frac{2molH_2}{2molH_2O}$ or $\frac{2molH_2O}{2molH_2}$ 

 

b) If you had 20 moles of hydrogen gas, how many moles of water could you make?

$20molH_2\times\frac{2molH_2O}{2molH_2}=$ 20 mol H₂O

 

c) oxygen gas to water:  $\frac{1molO_2}{2molH_2O}$ or $\frac{2molH_2O}{1molO_2}$ 

 

d) If you had 20 moles of oxygen gas, how many moles of water could you make?

$20molO_2\times\frac{2molH_2O}{1molO_2}=$ 40 mol H₂O

 

 

 

5.     N₂     +    3H₂        2NH₃

 

a) If 1 mole of nitrogen gas were used, how many moles of ammonia would be produced?

$1molN_2\times\frac{2molNH_3}{1molN_2}=$ 2 mol NH₃

 

b) If 10 moles of ammonia were produced, how many moles of nitrogen gas would be required?

$10molNH_3\times\frac{1molN_2}{2molNH_3}=$ 5 mol N₂

 

c) If 3.00 moles of hydrogen gas were used, how many moles of ammonia would be produced?

$3.00molH_2\times\frac{2molNH_3}{3molH_2}=$ 2 mol NH₃ 

 

d) If 0.600 moles of ammonia were produced, how many moles of hydrogen gas would be required?

$0.600molNH_3\times\frac{3molH_2}{2molNH_3}=$ 0.900 mol H₂

 

 

 

6.    2NaI    +     Cl₂        2NaCl      +      I₂

 

a) How many moles of sodium chloride would be produced when 5.00 moles of chlorine gas are used?

$5.00molCl_2\times\frac{2molNaCl}{1molCl_2}=$ 10 mol NaCl

 

b) If 3.50 moles of sodium chloride are produced, how many moles of chlorine gas must be used?

$3.50molNaCl\times\frac{1molCl_2}{2molNaCl}=$ 1.75 mol Cl₂

 

c) Given the data in part b, how many moles of sodium iodide must be used?

$3.50molNaCl\times\frac{2molNaI}{2molNaCl}=$ 3.50 mol NaI

 

d) If 4.75 moles of sodium iodide are used, how many moles of pure iodine are produced?

$4.75molNaI\times\frac{1molI_2}{2molNaI}=$ 2.38 mol I₂