Question

mole conversions practice worksheet
mass → moles → moles → mass
(use molar masses and mole ratios from balanced equations as needed.)

1. how many grams of hydrogen gas are produced when 12.0 g of zinc reacts with excess hydrochloric acid?

zn + hcl → zncl₂ + h₂

1. how many grams of water are produced when 5.00 g of hydrogen reacts with excess oxygen?

h₂ + o₂ → h₂o

1. how many grams of carbon dioxide are produced from 15.0 g of methane burned in oxygen?

ch₄ + o₂ → co₂ + h₂o

1. if 22.0 g of sodium reacts with chlorine gas, how many grams of nacl are formed?

na + cl₂ → nacl

1. how many grams of ammonia will form from 28.0 g of nitrogen gas and excess hydrogen?

n₂ + h₂ → nh₃

Explanation:

Step1: Balance the chemical equation

$$\mathrm{Zn}+2\mathrm{HCl} ightarrow\mathrm{ZnCl}_{2}+\mathrm{H}_{2}$$

Step2: Calculate the moles of Zn

The molar mass of Zn is \(M_{\mathrm{Zn}} = 65.38\space g/mol\).
The moles of Zn, \(n_{\mathrm{Zn}}=\frac{m_{\mathrm{Zn}}}{M_{\mathrm{Zn}}}=\frac{12.0\space g}{65.38\space g/mol}\approx0.184\space mol\)

Step3: Use mole ratio

From the balanced equation, the mole ratio of \(\mathrm{Zn}\) to \(\mathrm{H}_{2}\) is \(1:1\). So \(n_{\mathrm{H}_{2}} = n_{\mathrm{Zn}}= 0.184\space mol\)

Step4: Calculate the mass of \(H_{2}\)

The molar mass of \(H_{2}\) is \(M_{\mathrm{H}_{2}}=2.016\space g/mol\)
\(m_{\mathrm{H}_{2}}=n_{\mathrm{H}_{2}}\times M_{\mathrm{H}_{2}}=0.184\space mol\times2.016\space g/mol\approx0.371\space g\)

Answer:

Approximately \(0.371\space g\) of hydrogen gas is produced.