Amounts of substance in equations

Figure 11 shows part of the reactivity series of metals.

The method used to extract a metal from its ore is related to the metal’s position in the reactivity series.

Which metal is found in the Earth’s crust as an uncombined element?

Name one metal in Figure 11 that is normally extracted by electrolysis.

25 000 kg of an ore of iron was found to contain 10 050 kg of iron.

Calculate the percentage of iron in this ore of iron.

percentage of iron in ore =_........

When copper oxide is heated with carbon, the products are copper and carbon dioxide.

Write the word equation for this reaction.

In this reaction, copper oxide loses oxygen.

State the type of reaction when copper oxide loses oxygen.

In one reaction, 159.0 g of copper oxide was heated with excess carbon to produce 127.0 g of copper.

Use this information to calculate the mass of copper formed, in g, when 238.5 g of copper oxide is reacted with excess carbon.

mass of copper =_........ g

State why this reaction with copper oxide uses excess carbon.

A solution of zinc sulfate was made by dissolving 23.8 g of the compound in water and was made up to a total volume of 250 cm³ with water.

Calculate the concentration of this solution in g dm^–3.

Give your answer to 2 significant figures.

concentration =_........ g dm^–3

Malachite, Cu₂CO₃(OH)₂, is a mineral containing copper.

When heated, malachite decomposes to form copper oxide, carbon dioxide and water.

Which apparatus should be used to heat the malachite and test for carbon dioxide?

When carbon dioxide is bubbled through limewater, a precipitate forms. This precipitate solid makes the limewater cloudy.

Name the precipitate that makes the limewater cloudy.

The equation for the decomposition of malachite when it is heated is

Calculate the maximum mass of copper oxide that can be formed when 22.1 g of malachite is decomposed completely.

(relative atomic masses: Cu = 63.5, O = 16.0, C = 12.0, H = 1.0)

maximum mass of CuO =_........

Copper can be extracted from copper oxide by heating the copper oxide with carbon.

A student investigated two methods to extract the maximum mass of copper from copper oxide.

Figure 3 shows the two methods.

Comment on the strengths and weaknesses of these two methods.

Figure 4 shows the structure of molecules of three compounds, A, B and C.

Explain which compound, A, B or C, is an alkene.

What is the empirical formula of compound B ?

The test to distinguish between compounds B and C involves shaking separate samples of each compound with an orange solution.

The label on the orange solution is shown in Figure 5.

State the meaning of the hazard symbol shown.

Name the orange solution used to distinguish between compounds B and C.

What is the final appearance of the mixture when compound B is shaken with a few drops of the orange solution?

The molecular formula of compound A is C₄H₁₀O.

A sample of compound A undergoes complete combustion to form carbon dioxide and water.

Explain why this reaction is an oxidation reaction.

Calculate the mass of water formed from the complete combustion of 74 g of compound A, C₄H₁₀O.

(relative formula masses: C₄H₁₀O = 74, H₂O = 18)

Crisp packets are often made from poly(propene) coated with a thin layer of aluminium on the inside.

Poly(propene) is a polymer made from the monomer propene, CH₂CHCH₃.

What is the relative formula mass of propene?

(relative atomic masses: C = 12, H = 1)

Describe how monomer molecules combine to make polymers.

Crisps go stale when exposed to the atmosphere.

In an experiment some crisp packets were made from aluminium, some from poly(propene) and some from poly(propene) coated with aluminium. These packets were tested.

Figure 15 shows the results.

Low porosity is an advantage of using poly(propene) coated with aluminium as it prevents the crisps from becoming damp.

Explain, using Figure 15, one other advantage of using poly(propene) coated with aluminium.

The aluminium coating can be replaced by a very thin layer of material called a nanosheet.

The nanosheet is made from amino acids and is less than 100 nm thick.

Explain why the nanosheet layer would be better than aluminium as a coating for crisp packets.

Nanosheet layers can be made from amino acids.

An equation showing a reaction of an amino acid, C₂H₅NO₂, is

Calculate the mass of water formed when 105 g of this amino acid reacts.

(relative formula masses: C₂H₅NO₂ = 75, H₂O = 18)

Some crisps contain malic acid.

The structure of one molecule of malic acid is shown in Figure 16.

Malic acid has two types of functional group.

One type is the –COOH functional group.

Give the name of this functional group.

Name the other functional group.

Crisp packets are often made from poly(propene) coated with a thin layer of aluminium on the inside.

Poly(propene) is a polymer made from the monomer propene, CH₂CHCH₃.

What is the relative formula mass of propene?

(relative atomic masses: C = 12, H = 1)

Describe how monomer molecules combine to make polymers.

Crisps go stale when exposed to the atmosphere.

In an experiment some crisp packets were made from aluminium, some from poly(propene) and some from poly(propene) coated with aluminium. These packets were tested.

Figure 5 shows the results.

Low porosity is an advantage of using poly(propene) coated with aluminium as it prevents the crisps from becoming damp.

Explain, using Figure 5, one other advantage of using poly(propene) coated with aluminium.

The aluminium coating can be replaced by a very thin layer of material called a nanosheet.

The nanosheet is made from amino acids and is less than 100 nm thick.

Explain why the nanosheet layer would be better than aluminium as a coating for crisp packets.

Nanosheet layers can be made from amino acids.

An equation showing a reaction of an amino acid, C₂H₅NO₂, is

Calculate the mass of water formed when 105 g of this amino acid reacts.

(relative formula masses: C₂H₅NO₂ = 75, H₂O = 18)

Some crisps contain malic acid.

The structure of one molecule of malic acid is shown in Figure 6.

Malic acid has two types of functional group.

One type is the –COOH functional group.

Give the name of this functional group.

Name the other functional group.

An investigation was carried out on the reactivity of four metals, D, E, F and G.

Equal sized pieces of these metals were placed in excess dilute hydrochloric acid and left for three minutes.

Figure 9 shows the observations of the reactions for metals D, E and F.

The order of reactivity for these metals is shown in Figure 10.

most reactive least reactive

Figure 10

Use the information in Figure 9 and Figure 10 to suggest the observations that would be made for metal G.

The dilute hydrochloric acid used in this reaction is a strong acid.

Explain the meaning of the terms dilute and strong acid.

dilute

strong acid

The formula of lead ethanoate is Pb(CH₃COO)₂.

Calculate the number of atoms that combine together to form 16.25 g of lead ethanoate.

(relative atomic masses: H = 1.00, C = 12.0, O = 16.0, Pb = 207

Avogadro number = 6.02×10²³)

number of atoms =_........

Iron is more reactive than copper.

Iron will displace copper from copper nitrate solution. Two possible balanced equations for the reaction are

It was found that 2.24 g of iron reacted with excess copper nitrate solution to form 3.81 g of copper.

Carry out a calculation, using the information above, to show which equation represents the reaction taking place.

(relative atomic masses: Fe = 56.0, Cu = 63.5)

There are several stages to the production of sulfuric acid in industry.

Sulfur dioxide is required for the production of sulfuric acid.

Sulfur dioxide can be obtained by heating copper sulfide, Cu₂S, in excess air.

Calculate the atom economy for the production of sulfur dioxide, SO₂, in this reaction.

(relative atomic mass: Cu = 63.5 relative formula masses: O₂ = 32.0, Cu₂S = 159.0, SO₂ = 64.0)

Give your answer to two significant figures.

In one stage vanadium oxide, V₂O₅, is used.

Based on the position of vanadium in the periodic table, which row shows the most likely melting point of vanadium and colour of vanadium oxide?

The equation shows a reaction forming sulfuric acid.

Calculate the maximum mass of sulfuric acid that could be produced from 400 tonnes of sulfur trioxide, SO₃.

(relative formula masses: SO₃ = 80, H₂SO₄ = 98)

maximum mass of sulfuric acid =_........ tonnes

Using a different amount of sulfur trioxide, it was calculated that 700 tonnes of sulfuric acid could be made.

The actual mass produced was 672 tonnes.

Calculate the percentage yield of sulfuric acid.

There are several stages to the production of sulfuric acid in industry.

Sulfur dioxide is required for the production of sulfuric acid.

Sulfur dioxide can be obtained by heating copper sulfide, Cu₂S, in excess air.

Calculate the atom economy for the production of sulfur dioxide, SO₂, in this reaction.

(relative atomic mass: Cu = 63.5 relative formula masses: O₂ = 32.0, Cu₂S = 159.0, SO₂ = 64.0)

Give your answer to two significant figures.

atom economy =_........

In one stage vanadium oxide, V₂O₅, is used.

Based on the position of vanadium in the periodic table, which row shows the most likely melting point of vanadium and colour of vanadium oxide?

The equation shows a reaction forming sulfuric acid.

Calculate the maximum mass of sulfuric acid that could be produced from 400 tonnes of sulfur trioxide, SO₃.

(relative formula masses: SO₃ = 80, H₂SO₄ = 98)

maximum mass of sulfuric acid =_........ tonnes

Using a different amount of sulfur trioxide, it was calculated that 700 tonnes of sulfuric acid could be made.

The actual mass produced was 672 tonnes.

Calculate the percentage yield of sulfuric acid.

percentage yield =_........

State two reasons why the percentage yield is less than 100 %.

A student carried out an investigation to determine the order of reactivity of four metals, W, X, Y and Z. A piece of metal W was added to a test tube containing excess dilute hydrochloric acid. This was repeated with the other three metals, X, Y and Z. In each case, the size of each piece of metal was the same. The student recorded observations on each reaction for three minutes.

The observations obtained are shown in Figure 8.

Use the information in Figure 8 to place the metals in order of reactivity from the least reactive to the most reactive.

The experiment was repeated using an excess of dilute sulfuric acid in place of the dilute hydrochloric acid.

metal + sulfuric acid metal sulfate + hydrogen

When metal Y reacts with dilute sulfuric acid, bubbles form quickly at first and then the reaction stops. Most of the solid metal remains.

Explain why the reaction between metal Y and excess dilute sulfuric acid stopped even though there was solid metal Y left.

The reactions between metals and dilute ethanoic acid are slower than reactions between metals and dilute hydrochloric acid. This is because ethanoic acid is a weak acid.

Explain the meaning of the term weak acid.

The formula of aluminium sulfate is Al₂(SO₄)₃.

Calculate the total number of atoms that combine to form 5.13 g of aluminium sulfate.

(relative atomic masses: O = 16.0, A l = 27.0, S = 32.0 Avogadro number = 6.0210²³)

number of atoms =_........

Iron is more reactive than lead. Iron reacts with lead nitrate solution to form solid lead. Two possible balanced equations for the reaction are

Equation 1 Fe + Pb(NO₃)₂ Fe(NO₃)₂ + Pb

Equation 2 2Fe + 3Pb(NO₃)₂ 2Fe(NO₃)₃ + 3Pb

In one experiment, it was found that 4.48 g of iron reacted with excess lead nitrate solution to form 24.84 g of lead.

Carry out a calculation, using the information above, to show which equation represents the reaction taking place.

(relative atomic masses: Fe = 56.0, Pb = 207)

This question is about some of the elements in group 7 of the periodic table.

Which row in the table correctly shows the colours and physical states of the elements at room temperature?

The compound phosphorus oxychloride has the formula POCl₃.

Calculate the percentage by mass of chlorine in phosphorus oxychloride.

(relative atomic masses: O = 16.0, P = 31.0, C l = 35.5)

percentage by mass of chlorine =_........

When iron reacts with chlorine, iron chloride is formed.

Two possible equations for this reaction are

A Fe + Cl₂ FeCl₂ B 2Fe + 3Cl₂ 2FeCl₃

In an experiment, 8.40 g iron reacts with chlorine to form 19.05 g iron chloride.

Show, using a calculation, which reaction, A or B, is taking place.

You must show your working.

(relative atomic masses: C l = 35.5, Fe = 56.0)

*(d) Group 1 metals react with the elements from group 7 to form salts.

Some examples of these reactions are shown in Figure 10.

You will find the position of these elements in their groups on the periodic table.

Explain, in terms of their electronic configurations and the relative reactivity of these elements, which of the reactions shown in Figure 10 would be the most violent.

Propanol, C₃H₇OH, can undergo reactions to form compounds Y and Z shown in Figure 14.

Figure 14

What happens to propanol when it forms compound Y ?

Compound Y can also be formed in the following reaction

C H C H

Explain how bromine water can be used to distinguish between compound X and compound Y.

Compound Z is a carboxylic acid.

Which of the following shows the functional group of a carboxylic acid?

Compound Z is an acid and turns litmus and universal indicator papers red. Compound Z also shows other acidic properties.

Devise an experiment that would show another acidic property of compound Z.

The balanced equation for the production of ethanol from the carbohydrate sucrose is

sucrose

Calculate the minimum mass of sucrose needed to produce 26.9 g of ethanol.

(relative formula masses: C₂H₅OH = 46, C₁₂H₂₂O₁₁ = 342)

minimum mass of sucrose =_........

Calculate the total number of atoms in 10.0 g of sucrose, C₁₂H₂₂O₁₁.

(relative formula mass: C₁₂H₂₂O₁₁ = 342; Avogadro constant = 6.02 × 10²³)

number of atoms =_........

Methane is a hydrocarbon fuel.

Complete the word equation for the complete combustion of methane in oxygen.

methane +_........ water +_........

The incomplete combustion of methane can produce carbon and carbon monoxide.

Give the reason why carbon and carbon monoxide are produced in the incomplete combustion of methane.

Crude oil is a complex mixture of hydrocarbons. Crude oil can be separated into useful fractions by fractional distillation.

Figure 10 shows a fractional distillation column and the fractions produced when crude oil is distilled.

Name the fraction in Figure 10 that is used to surface roads.

Name the fraction in Figure 10 that contains hydrocarbons with the lowest boiling point.

When crude oil is fractionally distilled, the demand for some fractions is more than the amount produced.

Figure 11 shows the relative amounts of each fraction in a crude oil and the relative demand for each of these fractions.

Which of the following shows the fractions where the relative demand is greater than the relative amount in the crude oil?

Cracking involves the breaking down of large hydrocarbon molecules into smaller hydrocarbon molecules.

Octane, C₈H₁₈, can be cracked to produce one molecule of ethene, C₂H₄, and one molecule of C_xH₁₄.

Determine the value of x in the molecule of C_xH₁₄.

Dodecane is a large hydrocarbon molecule. When one molecule of dodecane is cracked the products are one molecule of octane and one molecule of butene.

dodecane octane + butene

Calculate the maximum mass of octane that could be produced when 340 g of dodecane is cracked in this reaction.

(relative formula masses: dodecane = 170, octane = 114)

Figure 10 shows a flask fitted with a cotton wool plug. The flask contains an aqueous solution of a carbohydrate.

State two steps that need to be taken to turn the solution of the carbohydrate in the flask into a solution of ethanol.

The apparatus in Figure 11 is used to increase the concentration of the dilute solution of ethanol.

This apparatus did not produce a very concentrated solution of ethanol.

Describe how the apparatus can be altered to produce a more concentrated solution of ethanol.

The equation for the fermentation of a carbohydrate is

Calculate the maximum mass of carbon dioxide that could be produced if 135 g of this carbohydrate is fully fermented.

(relative formula masses: CO₂ = 44; C₆H₁₂O₆ = 180)

*(c) Figure 12 shows information about some compounds in the same homologous series.

Explain, using the data in Figure 12, why these compounds belong together in the same homologous series.

An aluminium atom has the atomic number 13 and the mass number 27.

Which row shows the numbers of subatomic particles present in an

Magnesium burns in excess oxygen to form magnesium oxide. The balanced equation for this reaction is

Starting with 1.35 g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction. (relative atomic masses: O = 16.0, Mg = 24.0)

You must show your working.

Chlorine reacts with hydrogen to form hydrogen chloride.

Write the balanced equation for this reaction.

*(d) Sodium chloride is an ionic compound, containing sodium ions, Na⁺, and chloride ions, Cl^–.

Figure 15 shows the electronic configuration of sodium and chlorine.

Explain how sodium and chlorine atoms form the ions in sodium chloride and how the ions are arranged in the solid sodium chloride.

You may wish to use diagrams in your answer.

An aluminium atom has the atomic number 13 and the mass number 27.

Which row shows the numbers of subatomic particles present in an

Magnesium burns in excess oxygen to form magnesium oxide. The balanced equation for this reaction is

Starting with 1.35 g of magnesium, calculate the maximum mass of magnesium oxide that could be formed in this reaction. (relative atomic masses: O = 16.0, Mg = 24.0)

You must show your working.

Chlorine reacts with hydrogen to form hydrogen chloride.

Write the balanced equation for this reaction.

Sodium reacts with chlorine to form sodium chloride.

The electronic configuration of the sodium atom is 2.8.1 and the electronic configuration of the chlorine atom is 2.8.7.

Give the electronic configurations of the ions formed.

Most metals are extracted from ores found in the Earth’s crust.

The method used to extract a metal from its ore is linked to the reactivity of the metal.

Part of the reactivity series is shown in Figure 14.

Iron ore contains iron oxide.

Iron is extracted from iron oxide by heating the oxide with carbon.

iron carbon

In this reaction

The formula of the iron oxide is Fe₂O₃.

Calculate the maximum mass of iron that can be obtained from 240 tonnes of iron oxide, Fe₂O₃.

(relative atomic masses: O = 16, Fe = 56)

mass of iron =_........ tonnes

Aluminium cannot be extracted by heating its oxide with carbon. Aluminium has to be extracted from its oxide by electrolysis.

Explain why.

Predict the method that will have to be used to extract calcium from its ore.

*(d) Aluminium is extracted from its ore by electrolysis. Iron is extracted from its ore by heating with carbon. Both metals can also be obtained by recycling.

Explain the advantages of recycling aluminium and iron rather than extracting them from their ores.

Most metals are extracted from ores found in the Earth’s crust.

The method used to extract a metal from its ore is linked to the reactivity of the metal.

Part of the reactivity series is shown in Figure 2.

Iron ore contains iron oxide.

Iron is extracted from iron oxide by heating the oxide with carbon.

iron carbon

In this reaction

The formula of the iron oxide is Fe₂O₃.

Calculate the maximum mass of iron that can be obtained from 240 tonnes of iron oxide, Fe₂O₃.

(relative atomic masses: O = 16, Fe = 56)

mass of iron =_........ tonnes

Aluminium cannot be extracted by heating its oxide with carbon. Aluminium has to be extracted from its oxide by electrolysis.

Explain why.

Predict the method that will have to be used to extract calcium from its ore.

In recent years, researchers have been investigating alternative methods of extracting metals from soils.

Researchers have found that growing certain plants in appropriate areas can result in the phytoextraction of copper.

Describe how growing plants can result in the phytoextraction of copper.

(a) A student placed a piece of metal P in a test tube containing excess dilute sulfuric acid. The student repeated this with three other metals, Q, R and S. All the pieces of all four metals were the same size.

The student recorded the observations until each metal had reacted with the acid for two minutes. The observations are shown in Figure 9.

Use this information to put the four metals in order of reactivity from the least reactive to the most reactive.

least reactive
most reactive

Complete the diagram below to show how the student could add to the apparatus to measure the volume of gas produced in the two minutes.

When iron reacts with copper sulfate solution, solid copper is formed.

Two possible equations for this reaction are

A CuSO₄ + Fe Cu + FeSO₄ B 3CuSO₄ + 2Fe 3Cu + Fe₂(SO₄)₃

It was found that 10.00 g of iron powder reacted with excess copper sulfate solution to produce 11.34 g of copper.

Carry out a calculation to decide which equation, A or B, represents the reaction taking place. (relative atomic masses: Fe = 56.0, Cu = 63.5)

Acid solutions contain hydrogen ions.

Aluminium reacts with dilute hydrochloric acid to form a solution containing aluminium ions, Al³⁺.

Complete the balanced ionic equation for this reaction.

The hydrogen ion concentration in a solution is decreased by a factor of 10.

State how the pH of this solution changes.

Calculate the mass, in g, of a hydrogen atom, using the data below. (relative atomic mass: H = 1.00; Avogadro constant = 6.02 × 10²³)