Question

1. Consider a situation in which 136 g of P4 are exposed to 144 g of O2.

Part A What is the maximum amount in moles of P2O5 that can theoretically be made from 136 g of P4 and excess oxygen?

Express your answer to three significant figures and include the appropriate units.

Part B What is the maximum amount in moles of P2O5 that can theoretically be made from 144 g of O2 and excess phosphorus?

Express your answer to three significant figures and include the appropriate units.

2. Butane, C4H10, reacts with oxygen, O2, to form water, H2O, and carbon dioxide, CO2, as shown in the following chemical equation:

2C4H10(g)+13O2(g)→10H2O(g)+8CO2(g)

The coefficients in this equation represent mole ratios. Notice that the coefficient for water (10) is five times that of butane (2). Thus, the number of moles of water produced is five times the number of moles of butane that react.

Also, notice that the coefficient for butane (2) is one-fourth the coefficient of carbon dioxide (8). Thus, the number of moles of butane that react is one-fourth the number of moles of carbon dioxide that you produce.

But be careful! If you are given the mass of a compound, you must first convert to moles before applying these ratios.

1. Calculate the mass of water produced when 1.19 g of butane reacts with excess oxygen.

Express your answer to three significant figures and include the appropriate units.

2. Calculate the mass of butane needed to produce 60.4 g of carbon dioxide.

Express your answer to three significant figures and include the appropriate units.

Answer 1

1)

Part A

136 g of P4 and excess oxygen

The atomic mass of P and O are 31.0 g/mol and 16 g/mol respectively.

The molar mass of g/mol

The molar mass of g/mol

136 g

1.0968 mol

Part B

144 g of

4.5 mole

Butane example

(1)

The molar mass of butane is 58.12 g/mol.

1.19 g butane

the number of moles of water produced when 1.19 g of butane reacts with excess oxygen

The molar mass of water is 18 g/mol.

the mass of water produced when 1.19 g of butane reacts with excess oxygen

(2)

The molar mass of CO2 is 44 g/mol. 60.4 g of CO2

The number of moles of butane needed to produce 60.4 g of carbon dioxide

The molar mass of butane is 58.12 g/mol.

The mass of butane needed to produce 60.4 g of carbon dioxide