Nitrogen and sulfur

In certain rice-growing regions, farmers combine paddy fields with a fish farm. The paddy fields remain flooded for most of the growing period, and water leaving the fields passes through pens in which fish are reared. Nitrogen-based fertilizers are usually highly soluble in water. Which problems could happen if farmers add too much nitrogen-based fertilizer to their paddy fields?

Feb/March 2016

In what different forms can nitrogen be present in compounds?

Feb/March 2018

Ammonia, $\text{NH}_3$, and hydrazine, $\text{NH}_2\text{NH}_2$, are both nitrogen-containing compounds, $\text{N}_2$. Which of the statements is correct?

Feb/March 2019

Nitrogen, $\text{N}_2$, is the most plentiful gas in the Earth’s atmosphere and is highly unreactive.

Feb/March 2019

Solid ammonium nitrate is placed in a test-tube and solution X is added to it. The mixture formed is then warmed, and the gas released is tested using damp red litmus paper. The litmus paper changes colour from red to blue. What could be the identity of X and its role in the reaction?

Feb/March 2020

A student heats calcium nitrate crystals using the apparatus illustrated. A colourless gas escapes from the apparatus at Y. A flame is brought to this gas. Which observations would the student make?

Feb/March 2020

Which of the following statements about nitrogen or its compounds is correct?

Feb/March 2020

Nitrogen dioxide gas is formed when petrol burns in car engines. Which acids are formed in the atmosphere because nitrogen dioxide is released into the air?

Feb/March 2021

In the Contact process, the product is Z. Which reaction or process produces a gas that is able to neutralise an aqueous solution of Z?

Feb/March 2022

Two procedures are given. 1. Sulfur is burnt in excess oxygen, and then NO is added to the mixture of products. 2. Sulfur is burnt in excess oxygen, and then $\text{NO}_2$ is added to the mixture of products. Which of these procedures will result in some sulfur trioxide, $\text{SO}_3$?

Feb/March 2023

Nitrogen monoxide, NO, is a primary pollutant formed by petrol engines and present in their exhaust gases. Which reaction takes place in a catalytic converter and reduces the amount of nitrogen monoxide released?

Feb/March 2024

Bismuth belongs to Group 15 of the Periodic Table.

Feb/March 2024

Nitrogen, N$_2$, is usually a molecule that is not very reactive, although it does react in some conditions.

Feb/March 2024

Four atmospheric pollutants are given below. 1 nitrogen oxides 2 carbon monoxide 3 unburnt hydrocarbons 4 sulfur dioxide Which two pollutants react together to produce peroxyacetyl nitrate, PAN?

Feb/March 2025

Gas M is formed when $\text{NH}_4\text{Cl(aq)}$ is heated together with $\text{CaO(s)}$. Which row is correct?

Feb/March 2025

Within a car engine, the non-metal element X produces the pollutant oxide Y. Y then undergoes further oxidation to Z in the atmosphere. During this extra oxidation, $1$ mol of Y reacts with $\frac{1}{2}$ mol of gaseous oxygen. Which element could X be?

May/June 2010

Sulfur dioxide and sulfites are added to food to help with preservation. Why are they suitable for this use?

May/June 2010

The diagram, at a specified temperature $T$, presents a Boltzmann distribution for the kinetic energy of the molecules in a mixture of two gases that react with each other. The activation energy for the reaction, $E_a$, is shown.

May/June 2010

Hydrazine, $\text{N}_2\text{H}_4$, is a liquid rocket fuel. It burns exothermically in oxygen to form only gaseous substances. The enthalpy change for a reaction such as hydrazine reacting with oxygen can be worked out from standard enthalpy changes of formation.

May/June 2010

Nitrogen monoxide, NO, is a primary pollutant formed by petrol engines and present in their exhaust gases. Which reaction takes place in a catalytic converter and lowers the emission of nitrogen monoxide?

May/June 2011

Petrol engines give rise to the primary pollutant nitrogen monoxide, $\text{NO}$, which is carried in exhaust gases. Which reaction in a catalytic converter lowers nitrogen monoxide emission?

May/June 2011

Ammonium nitrate, $\text{NH}_4\text{NO}_3$, is produced on a large scale for use in fertiliser. Which statement about ammonium nitrate fertiliser is incorrect?

May/June 2011

Which statements about the ammonium ion are correct?

May/June 2011

Carbon monoxide, $\text{CO}$, nitrogen monoxide, $\text{NO}$, and sulfur dioxide, $\text{SO}_2$, can all be found in the exhaust gases from a car engine. Which reaction involving these compounds takes place in the atmosphere?

May/June 2012

Ammonia and chlorine react in the gas phase. $8\text{NH}_3 + 3\text{Cl}_2 \rightarrow \text{N}_2 + 6\text{NH}_4\text{Cl}$ Which of the following statements is correct?

May/June 2012

In the exhaust fumes from a car engine, carbon monoxide, CO, nitrogen monoxide, NO, and sulfur dioxide, $\text{SO}_2$, may all be found. Which atmospheric reaction involving these compounds takes place?

May/June 2012

Nitrogen and phosphorus are both placed in Group V of the Periodic Table. Phosphorus makes a chloride with the formula $\text{PCl}_5$. Why is it impossible for nitrogen to form $\text{NCl}_5$?

May/June 2012

Ammonium sulfate, $(\text{NH}_4)_2\text{SO}_4$, is commonly used as a fertiliser. To find its percentage purity, a fertiliser sample of ammonium sulfate was tested by reacting a known quantity with excess of $\text{NaOH(aq)}$ and then titrating the leftover $\text{NaOH}$ with dilute $\text{HCl}$.

May/June 2012

Which reagent, if heated together with ammonium sulfate, gives off ammonia?

May/June 2013

Which statement about ammonia is fully correct?

May/June 2013

A fertiliser sample was stated to contain only ammonium sulfate, $(\text{NH}_4)_2\text{SO}_4$, together with sand. A $2.96\,\text{g}$ portion of the solid fertiliser was warmed with $40.0\,\text{cm}^3$ of excess $\text{NaOH(aq)}$, and every trace of ammonia formed was boiled off. After the mixture had cooled, the leftover $\text{NaOH(aq)}$ was exactly neutralised by $29.5\,\text{cm}^3$ of $2.00\,\text{mol dm}^{-3}$ $\text{HCl}$. In another experiment, $40.0\,\text{cm}^3$ of the original $\text{NaOH(aq)}$ was exactly neutralised by $39.2\,\text{cm}^3$ of the $2.00\,\text{mol dm}^{-3}$ $\text{HCl}$.

May/June 2013

Ammonium nitrate fertiliser is obtained from ammonia. In the first stage of its manufacture, ammonia is catalytically oxidised to produce nitrogen monoxide, NO. This takes place at about $1 \times 10^3\,\text{kPa}$ (10 atmospheres) pressure and at $700$ to $850\,^{\circ}\text{C}$. The reaction equation is $4\text{NH}_3(g) + 5\text{O}_2(g) \rightleftharpoons 4\text{NO}(g) + 6\text{H}_2\text{O}(g)$ with $\Delta H^{\circ} = -906\,\text{kJ mol}^{-1}$.

May/June 2013

Ammonium sulfate is a fertiliser made by reacting ammonia with sulfuric acid.

May/June 2013

Chile saltpetre is a mineral occurring in Chile and Peru, made up mainly of sodium nitrate, $\text{NaNO}_3$. The mineral is purified to raise the proportion of the $\text{NaNO}_3$, which is used as a fertiliser and in some fireworks. To determine the purity of a sodium nitrate sample, the compound is heated in $\text{NaOH(aq)}$ with Devarda's alloy, which contains aluminium. This converts the sodium nitrate into ammonia, which is boiled off and then dissolved in acid. $3\text{NaNO}_3\text{(aq)} + 8\text{Al(s)} + 5\text{NaOH(aq)} + 18\text{H}_2\text{O(l)} \rightarrow 3\text{NH}_3\text{(g)} + 8\text{NaAl(OH)}_4\text{(aq)}$. The ammonia gas formed is absorbed in an excess of $\text{H}_2\text{SO}_4$ of known concentration: $2\text{NH}_3 + \text{H}_2\text{SO}_4 \rightarrow (\text{NH}_4)_2\text{SO}_4$. The unreacted $\text{H}_2\text{SO}_4$ is then determined by back-titration with $\text{NaOH}$ of known concentration: $\text{H}_2\text{SO}_4 + 2\text{NaOH} \rightarrow \text{Na}_2\text{SO}_4 + 2\text{H}_2\text{O}$.

May/June 2013

Carbon disulfide, $\text{CS}_2$, is a flammable, volatile liquid that is formed in small amounts in volcanoes.

May/June 2013

A proportion of crude oils contain $\text{H}_2\text{S}$. In refining, the Claus process turns the $\text{H}_2\text{S}$ into solid sulfur, and this is then taken off. reaction I $2\text{H}_2\text{S}(g) + 3\text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(l) + 2\text{SO}_2(g)$ reaction II $2\text{H}_2\text{S}(g) + \text{SO}_2(g) \rightarrow 2\text{H}_2\text{O}(l) + 3\text{S}(s)$ Which of the statements about the Claus process are correct?

May/June 2014

A hydrated double salt sample, $\mathrm{Cu(NH_4)}_x(\mathrm{SO}_4)_2\cdot6\mathrm{H}_2\mathrm{O}$, was heated with an excess of sodium hydroxide. Ammonia was released. The ammonia formed was absorbed in 40.0 cm$^3$ of 0.400 mol dm$^{-3}$ hydrochloric acid. The solution that remained then needed 25 cm$^3$ of 0.12 mol dm$^{-3}$ sodium hydroxide to neutralise the extra acid.

May/June 2014

Nitrogen dioxide, $\text{NO}_2$, may enter the atmosphere by several different routes.

May/June 2014

Mohr’s salt is a pale green, crystalline substance that dissolves in water. It contains two cations, one of which is $\text{Fe}^{2+}$, together with one anion, $\text{SO}_4^{2-}$. The identity of the second cation was found by warming Mohr’s salt with aqueous sodium hydroxide. A colourless gas was given off, and it dissolved readily in water to produce an alkaline solution. A green precipitate also appeared. What are the identities of the gas and the precipitate?

May/June 2015

Carbon monoxide, $\text{CO}$, nitrogen dioxide, $\text{NO}_2$, and sulfur dioxide, $\text{SO}_2$, are all atmospheric pollutants. Which reaction involving these compounds takes place in the atmosphere?

May/June 2015

In atmospheric reactions, which changes involve sulfur dioxide acting as a reagent or as a catalyst?

May/June 2015

Sulfuric acid is a significant chemical that has many uses. It is produced by the Contact process, and the first step is the conversion of sulfur or a sulfide ore, such as galena, $\text{PbS}$, into sulfur dioxide, $\text{SO}_2$.

May/June 2015

Which reaction does not add to the issue of acid rain?

May/June 2016

Which statement does not describe how acid rain affects the environment?

May/June 2016

Ammonium nitrate is an important fertiliser formed through the acid-base reaction of ammonia with nitric acid.

May/June 2016

Which statement concerning nitrogen or one of its compounds is correct?

May/June 2017

In some fireworks, powdered aluminium reacts with powdered barium nitrate. Heat is released, an unreactive gas is formed, and every nitrogen atom is reduced. What is the equation for this reaction?

May/June 2017

Acid rain remains an environmental issue. Which of the following statements about acid rain are correct? 1 Acid rain is produced when oxides of nitrogen or oxides of sulfur react with water in the atmosphere. 2 Acid rain leads to a rise in the concentration of heavy metal ions in water courses. 3 Nitrogen dioxide will catalyse the formation of $\text{SO}_3$ from $\text{SO}_2$ in the atmosphere.

May/June 2017

Sulfur dioxide is a pollutant in the atmosphere. What could happen if sulfur dioxide gas were released into the atmosphere?

May/June 2017

Nitrogen gas, $\text{N}_2$, shows very low reactivity.

May/June 2017

Sulfur trioxide, $\text{SO}_3$, is made from sulfur dioxide and oxygen in the Contact process. $\text{2SO}_2(\text{g}) + \text{O}_2(\text{g}) \rightleftharpoons \text{2SO}_3(\text{g}) \;\; \Delta H = -196.0\ \text{kJ mol}^{-1}$.

May/June 2017

Oxides of nitrogen occur in the environment because of both natural and human-made sources. Which row is correct?

May/June 2018

Which statements accurately describe how a nitrogen oxide acts as an atmospheric pollutant?

May/June 2018

Solid barium oxide is added to a sample of ammonium sulfate solution in a test tube, and the mixture is heated. A piece of damp red litmus paper is then held above the mouth of the test tube. What observations would be seen?

May/June 2018

The gaseous substances produced when a mixture of $\text{Ca(OH)}_2$ and $\text{NH}_4\text{Cl}$ is heated are led over solid CaO. The CaO removes water vapour, and gas W is then collected. A sample of W is oxidised by $\text{Cl}_2(g)$, forming two gases, X and Y. X is an element. Y is acidic. Y reacts with W to form Z. Identify X and Z.

May/June 2018

Sulfuric acid is made by the Contact process. One step in this process converts sulfur dioxide into sulfur trioxide in the presence of the heterogeneous catalyst vanadium(V) oxide, $\text{V}_2\text{O}_5$. The equation is: $2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightleftharpoons 2\text{SO}_3\text{(g)} \quad \Delta H = -196\,\text{kJ mol}^{-1}$

May/June 2018

Ammonium iron(II) sulfate, $(\text{NH}_4)_2\text{Fe(SO}_4)_2$, has a relative formula mass, $M_r$, equal to $284$.

May/June 2018

Which of the following statements is correct?

May/June 2019

Ammonium sulfate, $(\text{NH}_4)_2\text{SO}_4$, and ammonium nitrate, $\text{NH}_4\text{NO}_3$, are both used as fertilisers. These salts contain different percentages by mass of nitrogen. They have the same effect on the pH of wet neutral soil as each other. Which row is the correct one?

May/June 2019

Which reaction produces a product that is an atmospheric pollutant responsible for acid rain?

May/June 2019

In which reactions do the nitrogen atoms undergo reduction?

May/June 2019

A sample is made up of three distinct atom types: $^{40}_{18}\text{Ar}$, $^{40}_{19}\text{K}$ and $^{40}_{20}\text{Ca}$.

May/June 2019

The release of sulfur dioxide, $\text{SO}_2$, into the atmosphere leads to acid rain.

May/June 2019

Compound T appears as a white crystalline solid. If a sample of compound T is combined with aqueous sodium hydroxide and warmed, a gas is given off that turns damp red litmus paper blue. Additional testing on a solution of compound T with aqueous barium chloride gives a dense white precipitate that remains insoluble after dilute hydrochloric acid is added to the mixture. What compound is T?

May/June 2020

Nitrogen combines with oxygen to make nitrogen monoxide, $\text{NO}$, and nitrogen dioxide, $\text{NO}_2$. Nitrogen dioxide then reacts with water and also with hydroxide ions. $\text{N}_2(g) + \text{O}_2(g) \rightarrow 2\text{NO}(g)$ $2\text{NO}(g) + \text{O}_2(g) \rightarrow 2\text{NO}_2(g)$ $2\text{NO}_2(g) + \text{H}_2\text{O}(l) \rightarrow \text{HNO}_2(aq) + \text{H}^+(aq) + \text{NO}_3^{-}(aq)$ $2\text{NO}_2(g) + 2\text{OH}^-(aq) \rightarrow \text{NO}_2^{-}(aq) + \text{NO}_3^{-}(aq) + \text{H}_2\text{O}(l)$ What conclusions can be drawn from these equations alone?

May/June 2020

Nitric acid, $\text{HNO}_3$, is produced by reacting nitrogen dioxide with water. The reaction enthalpy change may be determined indirectly by means of a Hess’ cycle. $3\text{NO}_2(\text{g}) + \text{H}_2\text{O}(\ell) \xrightarrow{\Delta H_r} 2\text{HNO}_3(\ell) + \text{NO}(\text{g})$

May/June 2020

Ammonium nitrate and calcium carbonate are formed when calcium nitrate, $\text{Ca(NO}_3)_2$, reacts with ammonia, carbon dioxide and water. $\text{Ca(NO}_3)_2 + 2\text{NH}_3 + \text{CO}_2 + \text{H}_2\text{O} \rightarrow 2\text{NH}_4\text{NO}_3 + \text{CaCO}_3$

May/June 2020

Nitric acid can be produced by a process with 3 stages.

May/June 2020

Which substance is not formed during the thermal decomposition of hydrated magnesium nitrate?

May/June 2021

Acid rain consists of a dilute solution of sulfuric acid. Which pollutant also helps in the formation of acid rain?

May/June 2021

What environmental consequence can result from the uncontrolled use of nitrate fertilisers?

May/June 2021

Which problem may occur if farmers apply too much $\text{NH}_4\text{NO}_3$ to crops?

May/June 2021

Element X is a solid at room temperature. It is present as an impurity in fossil fuels. When fossil fuels are burnt, its oxide, Y, is produced. In the atmosphere, Y can then be oxidised further to Z. Which statements about X, Y and Z are correct?

May/June 2021

Whether a substance is a solid, a liquid or a gas at room temperature is determined by how strongly its particles attract one another.

May/June 2021

$\text{NCl}_3$ undergoes reaction with $\text{H}_2\text{O}$. $\text{NCl}_3 + 3\text{H}_2\text{O} \rightarrow \text{NH}_3 + 3\text{HClO}$ In this reaction, the oxidation state of nitrogen stays the same. Which statement is correct?

May/June 2022

A solid, R, is put into a solution of ammonium nitrate and the mixture is heated. A gas is released that changes red litmus paper to blue. What could R be?

May/June 2022

J and L are both elements in Group 15. Each of J and L forms a gaseous covalent hydride in which the oxidation number is $-3$. In the liquefied states of these hydrides, substantial hydrogen bonding is present only in the hydride of L. Which row concerning J and L could be correct?

May/June 2022

N$_2$(g) molecules consist of two atoms held together by a triple covalent bond.

May/June 2022

Which exhaust gas from an internal combustion engine causes marble statues to wear away?

May/June 2023

Which of the following statements about nitrogen oxides is correct?

May/June 2023

Nitrogen dioxide is a gas that adds to air pollution. It is formed in internal combustion engines. Which statement is correct?

May/June 2024

Nitrogen dioxide undergoes reaction with water. $2\text{NO}_2 + \text{H}_2\text{O} \rightarrow \text{HNO}_2 + \text{HNO}_3$ Which statement about this reaction is correct?

May/June 2024

$\text{NH}_4\text{Cl}$ reacts with $\text{NaOH}$ in aqueous solution. Which statement is correct?

May/June 2024

At room temperature, sulfur chloride, $\text{SCl}_2$, is a liquid. If $\text{SCl}_2$ is added to water, mist-like fumes appear and a solution is formed that makes universal indicator red.

May/June 2024

Explain why nitrogen gas, $\text{N}_2(g)$, is not very reactive.

May/June 2024

In the Haber process, $\text{N}_2(g)$ combines with $\text{H}_2(g)$, as illustrated by reaction 1. Reaction 1: $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$, $\Delta H = -x\,\text{kJ mol}^{-1}$. Table 2.1 gives the conditions used to make three equilibrium mixtures, A, B and C.

May/June 2024

$\text{NH}_3(g)$ reacts with $\text{HCl}(g)$ to form $\text{NH}_4\text{Cl}(s)$, as shown. $\text{NH}_3(g) + \text{HCl}(g) \rightarrow \text{NH}_4\text{Cl}(s)$ Draw a diagram that shows the ionic, covalent and coordinate bonding present in one formula unit of $\text{NH}_4\text{Cl}$.

May/June 2024

On the surface of a catalytic converter, which reduction process takes place?

May/June 2025

Sulfur dioxide in the atmosphere can lead to acid rain. This happens in two steps. 1 oxidation of $\text{SO}_2$ to $\text{SO}_3$ 2 formation of dilute $\text{H}_2\text{SO}_4$. Which row gives the atmospheric catalyst for step 1 and the reagent for step 2?

May/June 2025

The flow chart illustrates some reactions involving nitrogen compounds. gas 1 $\xrightarrow{\text{acid}}$ salt 1 $\xrightarrow{\text{alkali}}$ salt 2 + other products Which row correctly identifies gas 1 and salt 2?

May/June 2025

Which dot-and-cross diagrams show molecules that can react with unburned hydrocarbons to produce peroxyacetyl nitrate, PAN, a constituent of photochemical smog?

May/June 2025

Compound L has the empirical formula NH. When it is gently heated, it breaks down to form only ammonia and compound M. An aqueous solution of compound L conducts electricity well. Which row might be correct?

May/June 2025

Fig. 2.1 illustrates the covalent bonds and lone pairs of electrons in a molecule of $\text{SCl}_2$.

May/June 2025

Sulfur dioxide is employed to bleach wood pulp in paper manufacture. It is also added as an additive in the making of jam and marmalade, usually in the form of sulfite compounds. If its amount exceeds $10\ \text{mg kg}^{-1}$, it has to be declared as an ingredient in the jam. What is the reason for adding sulfur dioxide to jam?

Oct/Nov 2010

Which environmental problem is not worsened by the emission of oxides of nitrogen from car engines?

Oct/Nov 2010

Element X is a solid and is present as a contaminant in carbonaceous fuels. Its oxide Y is produced in car engines. In the atmosphere, Y may undergo further oxidation to Z. Which of the following statements about Y and Z are correct?

Oct/Nov 2010

Which environmental problem is not aggravated by oxides of nitrogen released from car engines?

Oct/Nov 2010

Element X is solid. It is present as an impurity in carbonaceous fuels. Its oxide Y is produced in car engines. Y may be further oxidised to Z in the atmosphere. Which statements about Y and Z are correct?

Oct/Nov 2010

Nitrogen accounts for roughly $79\%$ of the Earth’s atmosphere. It is also found in living things as a component element in proteins. The Haber process uses atmospheric nitrogen to produce ammonia.

Oct/Nov 2010

Nitrogen accounts for roughly $79\%$ of the Earth’s atmosphere. Because it is a constituent element of proteins, it is found in living organisms. Atmospheric nitrogen is used in the Haber process to make ammonia.

Oct/Nov 2010