Question

specific mass conversions quick check
hydrogen and oxygen react to produce water according to the following equation.
2h₂ + o₂ → 2h₂o
the molar mass of hydrogen gas (h₂) is 2 g/mol. the molar mass of oxygen gas (o₂) is 32 g/mol. when the reaction starts with 64 grams of oxygen and a sufficient quantity of hydrogen, how many moles of water are produced?
(1 point)
8
4
18
2

Explanation:

Step1: Calculate moles of \(O_2\)

Use the formula \(n=\frac{m}{M}\), where \(m = 64\space g\) (mass of \(O_2\)) and \(M = 32\space g/mol\) (molar mass of \(O_2\)).
\(n_{O_2}=\frac{64\space g}{32\space g/mol}= 2\space mol\)

Step2: Use mole - ratio from the balanced equation

From \(2H_2+O_2
ightarrow 2H_2O\), the mole - ratio of \(O_2\) to \(H_2O\) is \(1:2\).
If \(n_{O_2} = 2\space mol\), then \(n_{H_2O}=2\times n_{O_2}\)
\(n_{H_2O}=2\times2\space mol = 4\space mol\)

Answer:

4