If 454g of NH4NO3 decomposes, what mass of H2O is formed?

To convert from mass in grams of a reactant to volume, in liters, of a product (reverse the process for liters to

grams):

• Use factor label method

• Use mass of reactant from the Periodic Table 1 mol= g

• Use the mole to mole ratio from the balanced reaction

• Use mass of the product from the Periodic Table 1 mol= g

Example 1:

Ammonium nitrate (NH4NO3), an important fertilizer, produces dinitrogen monoxide (N2O) gas and H2O

when it decomposes. Determine the mass of H2O produced from the decomposition of 25.0 g of solid

NH4NO3.

Step 1: Write a balanced chemical equation:

NH4NO3  N2O + 2 H2O

Step 2: Start with your given:

25.0 g NH4NO3

Step 3: Convert grams to moles using the mass of the given from the Periodic Table:

2 N + 4 H + 3 O = 2(14.01) + 4(1.01) + 3(16) = 28.02 + 4.04 + 48 = 80.06 g/mol molar mass to mole

25.0 g NH4NO3 x 1 mol NH4NO3

80.06 g NH4NO3

Step 4: Convert moles of the given to moles of the unknown using the mole to mole ratio in the

balanced equation:

1 mol NH4NO3 : 2 mol H2O molar mass to mole mole to mole ratio

25.0 g NH4NO3 x 1 mol NH4NO3 x 2 mol H2O

80.06 g NH4NO3 1 mol NH4NO3

Step 5: Convert moles of the unknown to grams of the unknown from the Periodic Table: molar mass to mole mole to mole ratio mole to molar mass

25.0 g NH4NO3 x 1 mol NH4NO3 x 2 mol H2O x 18.02 g H2O 80.06 g NH4NO3 1 mol NH4NO3 1 mol H2O

Step 6: Check that all units cancel out except the unknown unit at the end; multiply across numerators

and divide by denominators: molar mass to mole mole to mole ratio mole to molar mass

25.0 g NH4NO3 x 1 mol NH4NO3 x 2 mol H2O x 18.02 g H2O = 11.3 g H2O 80.06 g NH4NO3 1 mol NH4NO3 1 mol H2O

Example 2:

How many grams of calcium hydroxide will be produced if 4.40 g of CaH2 reacts with water to form calcium

hydroxide and hydrogen gas?

Write a balanced equation: CaH2 + H2O  Ca(OH)2 + H2

Set up the factor label conversion:

molar mass to mole mole to mole ratio mole to molar mass

4.40 g CaH2 x x x = g Ca(OH)2

Explanation:

your answer would be “dry”