How much? the amount of chemical change: notes and practice questions

In an industrial process for ammonia synthesis, $100 \text{ cm}^3$ of nitrogen gas was mixed with $400 \text{ cm}^3$ of hydrogen gas in a reaction vessel. The reaction proceeded to completion according to the following equation:

$N_2(g) + 3H_2(g) \rightarrow 2NH_3(g)$

What is the volume of unreacted hydrogen gas remaining at the original conditions of temperature and pressure?

A. $50 \text{ cm}^3$

B. $100 \text{ cm}^3$

C. $200 \text{ cm}^3$

D. $300 \text{ cm}^3$

A student is investigating the reaction between aluminum metal and hydrochloric acid.

What are the limiting reactant and theoretical yield of hydrogen when $0.15 \text{ mol}$ of aluminum reacts with $0.40 \text{ mol}$ of hydrochloric acid?

$2Al(s) + 6HCl(aq) \rightarrow 2AlCl_3(aq) + 3H_2(g)$

A. Al, $0.15 \text{ mol}$

B. Al, $0.225 \text{ mol}$

C. HCl, $0.10 \text{ mol}$

D. HCl, $0.20 \text{ mol}$

A sample of butane, $C_4H_{10}(g)$, with a volume of $2.50 \text{ dm}^3$ is collected at $25.0 \text{ °C}$ and $100.0 \text{ kPa}$. How many moles of oxygen are needed for the complete combustion of this sample of butane?

A. $0.101$

B. $0.328$

C. $0.656$

D. $1.31$

In an industrial synthesis, equal volumes of nitrogen gas ($N_2$) and hydrogen gas ($H_2$) are mixed in a sealed reactor at constant temperature and pressure to produce ammonia gas ($NH_3$).

$N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)$

After the reaction reaches completion, the volume of ammonia gas produced is measured to be $30\text{ cm}^3$.

What was the initial volume, in $\text{cm}^3$, of nitrogen gas at the beginning of the reaction?

A. $15$

B. $30$

C. $45$

D. $90$

The dotted line in the graph below represents the volume of hydrogen gas evolved when excess solid zinc is added to $50.0\text{ cm}^3$ of $2.00\text{ mol dm}^{-3}$ hydrochloric acid.

Which curve (A, B, C, or D) represents the production of hydrogen gas when excess solid zinc is added to $100.0\text{ cm}^3$ of $0.500\text{ mol dm}^{-3}$ hydrochloric acid?

A. Curve A

B. Curve B

C. Curve C

D. Curve D

A sample of a gaseous hydrocarbon, $C_xH_y$, a component of liquefied petroleum gas (LPG), undergoes complete combustion. $15.0\ cm^3$ of the hydrocarbon reacts completely to produce $105.0\ cm^3$ of gaseous products. This volume reduces to $45.0\ cm^3$ when the water vapour present condenses. All volumes are measured at the same temperature and pressure.

What is the molecular formula of the hydrocarbon?

A. $C_2H_6$

B. $C_3H_6$

C. $C_3H_8$

D. $C_4H_{10}$

A student performs a redox titration to determine the concentration of iron(II) ions in a sample. The iron(II) ions are oxidized to iron(III) ions by dichromate(VI) ions, which are themselves reduced to chromium(III) ions.

$Cr_2O_7^{2-} (aq)$ reduced to $Cr^{3+}(aq)$

$Fe^{2+} (aq)$ oxidized to $Fe^{3+} (aq)$

What volume, in $cm^3$, of $0.020\ mol\ dm^{-3}\ Cr_2O_7^{2-} (aq)$ is required to reach the equivalence point in the titration of $25.00\ cm^3$ of $0.120\ mol\ dm^{-3}\ Fe^{2+} (aq)$?

A. 12.5

B. 25.0

C. 50.0

D. 150.0