Molarityand

Stoichiometry

1. Calculate the number of grams of sodium carbonate that are required to react fully with 125.0 mL of 0.958 M HCl.

Na2CO3(aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + CO2(g)

0.125L? g

0.125L HCl x 0.958 mol

1L

x 1 mol Na2CO3

2 mol HCl

x 106.0 g

1 mol= 6.35 g Na2CO3

2. How many milliliters of 0.698 M hydrochloric acid are needed to produce 3.4 L of sulphur dioxide gas at STP?

Na2SO3 (aq) + 2HCl (aq) → 2NaCl (aq) + H2O (l) + SO2(g)

? mL 3.4 L

3.4 L SO2

22.4 L

x 1 mol

1 mol SO2

x 2 mol HCl

0.698 mol

x 1 L x 1000 mL

1L

= 4.3 x 102 mL

3. What volume of 0.300 M KOH will neutralize 100.0 mL of 0.200 M H2SO4

1 H2SO4 + 2 KOH → 2 HOH + 1 K2SO4

? L0.1000 L

0.300 mol

x 1L x 2 mol KOH

1 mol H2SO4

x 0.200 mol

1L

0.1000 L H2SO4

= 0.133 L of KOH

4. 13.8 L of CO2 @ STP is dissolved in 250.0 mL of water. What is the molarity of the resulting solution?

Molarity =

0.250 L

x 1 mol13.8 L CO2

22.4 L

= 2.46 M

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