The chemical equation below shows the combustion of propane [tex]\((C_3H_8)\)[/tex]:

[tex]\[ C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O \][/tex]

The molar mass of oxygen gas [tex]\((O_2)\)[/tex] is [tex]\(32.00 \, \text{g/mol}\)[/tex]. The molar mass of [tex]\(C_3H_8\)[/tex] is [tex]\(44.1 \, \text{g/mol}\)[/tex].

What mass of [tex]\(O_2\)[/tex], in grams, is required to completely react with [tex]\(0.025 \, \text{g} \, C_3H_8\)[/tex]?

A. 0.018 grams
B. 0.034 grams
C. 0.045 grams
D. 0.091 grams



Answer :

To determine the mass of [tex]\( O_2 \)[/tex] required to completely react with [tex]\( 0.025 \, \text{g} \, C_3H_8 \)[/tex], we can follow a step-by-step approach that involves calculating the moles of propane, finding the stoichiometric moles of oxygen needed, and then converting that to mass.

1. Calculate the moles of [tex]\( C_3H_8 \)[/tex]:

The molar mass of [tex]\( C_3H_8 \)[/tex] is [tex]\( 44.1 \, \text{g/mol} \)[/tex]. Given the mass of [tex]\( C_3H_8 \)[/tex] is [tex]\( 0.025 \, \text{g} \)[/tex], we compute the moles of [tex]\( C_3H_8 \)[/tex] as follows:
[tex]\[ \text{moles of } C_3H_8 = \frac{0.025 \, \text{g}}{44.1 \, \text{g/mol}} = 0.0005668934240362812 \, \text{mol} \][/tex]

2. Determine the moles of [tex]\( O_2 \)[/tex] required:

According to the balanced chemical equation:
[tex]\[ C_3H_8 + 5 O_2 \rightarrow 3 CO_2 + 4 H_2O \][/tex]
1 mole of [tex]\( C_3H_8 \)[/tex] reacts with 5 moles of [tex]\( O_2 \)[/tex]. Therefore, the moles of [tex]\( O_2 \)[/tex] required are:
[tex]\[ \text{moles of } O_2 = 0.0005668934240362812 \, \text{mol} \times 5 = 0.002834467120181406 \, \text{mol} \][/tex]

3. Calculate the mass of [tex]\( O_2 \)[/tex]:

The molar mass of [tex]\( O_2 \)[/tex] is [tex]\( 32.00 \, \text{g/mol} \)[/tex]. Therefore, the mass of [tex]\( O_2 \)[/tex] required can be determined as:
[tex]\[ \text{mass of } O_2 = 0.002834467120181406 \, \text{mol} \times 32.00 \, \text{g/mol} = 0.09070294784580499 \, \text{g} \][/tex]

Thus, the mass of [tex]\( O_2 \)[/tex] required to completely react with [tex]\( 0.025 \, \text{g} \, C_3H_8 \)[/tex] is [tex]\( 0.091 \, \text{g} \)[/tex]. Hence, the correct answer is [tex]\( 0.091 \, \text{g} \)[/tex].