Relative formula mass

This question is about metals and their reactions with acids.

Place ticks () in boxes to show which elements in the table are metals.

Use the periodic table to help you answer this question.

Three equal sized pieces of the metals E, F, G and H are put into separate test tubes containing equal volumes of dilute sulfuric acid.

The results in Figure 6 show the test tubes after half a minute.

Arrange the metals E, F, G and H in order of reactivity.

The bubbles that form are hydrogen.

Which row of the table shows the test and result that confirm the gas is hydrogen?

When zinc reacts with very dilute nitric acid, zinc nitrate is formed.

The formula of zinc nitrate is Zn(NO₃)₂

Calculate the relative formula mass of zinc nitrate, Zn(NO₃)₂

(relative atomic masses: Zn = 65, N = 14, O = 16)

relative formula mass =_........

A student investigates the reaction between a metal and a dilute acid using the apparatus shown in Figure 7.

Cotton wool is placed in the top of the apparatus as shown, to stop any acid from spraying out.

The total mass of the apparatus is shown at the start of the reaction and after the reaction has ended.

start of reaction end of reaction

Figure 7

State two ways the student would know that the reaction has ended.

Figure 8 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 8 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 2 shows the two methods.

Comment on the strengths and weaknesses of these two methods.

Magnesium sulfate is an ionic compound.

A student adds magnesium sulfate to water to form a solution.

Which of these will also form a solution when added to water?

Calculate the percentage by mass of oxygen in magnesium sulfate, MgSO₄.

(relative atomic mass: O = 16.0 relative formula mass: MgSO₄ = 120)

Give your answer to 3 significant figures.

percentage by mass =_........

Calculate the number of oxygen atoms in 7.20 g of MgSO₄.

(relative formula mass: MgSO₄ = 120 Avogadro constant = 6.02 × 10²³)

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

*(c) Magnesium sulfate solution can be electrolysed using the apparatus shown in Figure 3.

Explain how the products are formed at the electrodes in terms of

• the ions present in the solution

• the oxidation and reduction reactions that take place at the electrodes.

You should include ionic equations as part of your answer.

Lithium is an alkali metal.

State which group of the periodic table contains the alkali metals.

Which of the following is a property of lithium?

A teacher adds a small piece of lithium to water containing universal indicator.

The universal indicator changes colour.

State the colour change shown by the universal indicator.

When lithium is added to water, lithium hydroxide and a gas are produced.

What is the name of the gas produced in this reaction?

Lithium hydroxide contains lithium ions, Li⁺.

Describe how a lithium atom becomes a lithium ion.

Calculate the percentage by mass of hydrogen in lithium hydroxide, LiOH.

(relative atomic masses: Li = 7, O = 16, H = 1.0)

Sodium carbonate has the formula Na₂CO₃.

Sodium carbonate contains Na⁺ ions and CO₃^2– ions.

The atomic number of sodium is 11.

What is the electronic configuration of the Na⁺ ion?

Explain why solid sodium carbonate cannot conduct electricity but a solution of sodium carbonate can conduct electricity.

Calculate the percentage by mass of sodium in sodium carbonate, Na₂CO₃.

(relative atomic masses: C = 12, O = 16, Na = 23)

percentage by mass of sodium =_........

*(c) A student has three solids, A, B and C.

The solids are sodium carbonate, powdered zinc and copper oxide, but the student does not know which solid is which.

The student reacted each solid with dilute sulfuric acid.

Figure 9 shows the student’s observations and the results of tests on any gases produced.

Use the observations and results in Figure 9 to identify which solid is which.

Your answer should include

• how each test result helps you to identify the solid

• word equations to support your answer.

Sodium carbonate has the formula Na₂CO₃.

Sodium carbonate contains Na⁺ ions and CO₃^2– ions.

The atomic number of sodium is 11.

What is the electronic configuration of the Na⁺ ion?

Explain why solid sodium carbonate cannot conduct electricity but a solution of sodium carbonate can conduct electricity.

Calculate the percentage by mass of sodium in sodium carbonate, Na₂CO₃.

(relative atomic masses: C = 12, O = 16, Na = 23)

percentage by mass of sodium =_........

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

The order of reactivity for these metals is shown in Figure 7.

most reactive
least reactive

Figure 7

Use the information in Figure 6 and Figure 7 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 =_........

This question is about bromine.

Give the colour and physical state of bromine at room temperature.

colour_........

physical state_........

Bromine reacts with hydrogen to form hydrogen bromide.

Write the word equation for this reaction.

Hydrogen bromide dissolves in water to form a solution.

This solution of hydrogen bromide reacts with alkalis.

State the type of reaction that occurs when a solution of hydrogen bromide reacts with an alkali.

Bromine and the other halogens react with hot iron wool.

Figure 7 shows the relative speed of some of these reactions.

Fluorine also reacts with hot iron wool.

Use Figure 7 to predict the relative speed of this reaction.

Potassium bromide contains 32.8% potassium by mass.

Calculate the mass of potassium and the mass of bromine in 500 g potassium bromide.

mass of potassium =_........ g

mass of bromine =_........ g

This question is about the atmosphere.

Describe the test to show that a gas is oxygen.

Copper reacts with oxygen to form copper oxide.

2.100 g of copper will react completely with 0.529 g of oxygen.

In an experiment, 4.200 g of copper is heated with 50.000 g of oxygen until the reaction is complete.

Calculate the mass of oxygen remaining at the end of the experiment.

mass of oxygen =_........ g

Helium, neon and argon are all inert.

Explain, in terms of electrons, why these gases are inert.

Two pieces of steel can be joined by heating the metal pieces with a very hot flame.

This process is often carried out in an argon atmosphere rather than in air.

Which property makes argon gas suitable for this use?

*(d) Figure 10 shows how plant life and the atmosphere of Earth have changed over time.

Explain the effect that plant life has had on the Earth’s atmosphere and the temperature of the Earth.

You should refer to the information in Figure 10 including

• the plant life

• the amounts of carbon dioxide

• the amounts of oxygen

Ammonia can be produced from the reaction of hydrogen with nitrogen.

What is the percentage by mass of nitrogen in ammonia, NH₃?

(relative atomic masses: H = 1.0, N = 14)

The reaction between hydrogen and nitrogen is exothermic.

Figure 8 shows the reaction profile of this exothermic reaction.

Which arrow represents the activation energy for the reaction?

Describe what the reaction profile shows about the energy involved in bond breaking and bond making in this reaction.

Ammonia, NH₃, and silicon dioxide, SiO₂, are both compounds that are made of two non-metallic elements.

Ammonia has a boiling point of –33 °C. Silicon dioxide has a boiling point of 2230 °C.

Explain why the boiling points of ammonia and silicon dioxide are so different.

Magnesium carbonate has the formula MgCO₃.

Magnesium carbonate contains Mg²⁺ and CO₃²⁻ ions.

The atomic number of magnesium is 12.

What is the electronic configuration of the Mg²⁺ ion?

Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium can.

Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO₃.

(relative atomic masses: C = 12.0, O = 16.0, Mg = 24.0)

percentage by mass of magnesium =_........

*(c) A student has two separate test tubes containing sulfuric acid.

The student adds a spatula measure of magnesium carbonate, MgCO₃, to the first test tube and a piece of magnesium to the second test tube.

Explain what the student would see in each test tube and the tests that they should carry out to identify the gases produced.

Your answer should include word equations for the reactions that would take place.

Magnesium carbonate has the formula MgCO₃.

Magnesium carbonate contains Mg²⁺ and CO₃²⁻ ions.

The atomic number of magnesium is 12.

What is the electronic configuration of the Mg²⁺ ion?

Explain why solid magnesium carbonate cannot conduct electricity but solid magnesium can.

Calculate the percentage by mass of magnesium in magnesium carbonate, MgCO₃.

(relative atomic masses: C = 12.0, O = 16.0, Mg = 24.0)

percentage by mass of magnesium =_........

Magnesium carbonate reacts with dilute hydrochloric acid. Water and carbon dioxide are two of the products of the reaction.

Complete the balanced equation for this reaction.

MgCO₃ + 2HCl _........ + H₂O + CO₂

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 6.

Use the information in Figure 6 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)

Figure 5 shows one molecule of a compound obtained from crude oil.

Give the names of the two elements in this molecule.

What is the molecule in Figure 5?

What is the relative formula mass of the compound in Figure 5?

(relative atomic masses: H = 1.0, C = 12)

Crude oil can be separated into different fractions.

Draw one straight line from each fraction to a use of that fraction.

Hydrogen chloride gas and sulfur dioxide gas are dissolved in separate test tubes of water. Blue litmus paper is dipped into each test tube.

State and explain the colour change you would observe in each test tube.

When chromium reacts with oxygen, chromium oxide is formed.

Write the word equation for this reaction.

What type of reaction occurs when chromium reacts with oxygen?

Calculate the relative formula mass of chromium oxide, Cr₂O₃.

(relative atomic masses: O = 16, Cr = 52)

relative formula mass =_........

Three different metals are added to separate test tubes of acid.

The observations are shown in Figure 2.

Place the metals in order of reactivity from most to least reactive.

most reactive_........

Hydrogen is given off when magnesium reacts with acid. The hydrogen is tested by collecting the gas in a test tube and igniting it.

What is the safest way to ignite the gas?

State the observation made in this test that shows that the gas is hydrogen.

Iron is extracted by heating iron oxide with carbon. Electrolysis of molten iron oxide is not used to extract iron.

State why iron can be extracted by heating iron oxide with carbon.

State why electrolysis is not used to extract iron.

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 7.

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 7 would be the most violent.

The word equation for the reaction between copper carbonate and dilute sulfuric acid is

copper sulfuric copper carbon

Complete the balanced equation for this reaction.

CuCO₃+_{........ ........} + CO₂+ H₂O

Calculate the relative formula mass of copper carbonate, CuCO₃. (relative atomic masses: C = 12.0, O = 16.0, Cu = 63.5)

relative formula mass of CuCO₃ =_........

What is the chemical test to show that a gas is carbon dioxide?

Figure 7 shows a conical flask containing dilute sulfuric acid. Copper carbonate is added to the acid in the flask. The copper carbonate is added one spatula measure at a time until the reaction has finished.

State two observations that would show the reaction has finished.

The word equation for the reaction between copper carbonate and dilute sulfuric acid is

copper sulfuric copper carbon

Complete the balanced equation for this reaction.

CuCO₃+_{........ ........} + CO₂+ H₂O

Calculate the relative formula mass of copper carbonate, CuCO₃. (relative atomic masses: C = 12.0, O = 16.0, Cu = 63.5)

relative formula mass of CuCO₃ =_........

What is the chemical test to show that a gas is carbon dioxide?

Figure 2 shows a conical flask containing dilute sulfuric acid. Copper carbonate is added to the acid in the flask. The copper carbonate is added one spatula measure at a time until the reaction has finished.

State two observations that would show the reaction has finished.

The electronic configuration of carbon is 2.4 The electronic configuration of oxygen is 2.6

Draw a dot and cross diagram for a molecule of carbon dioxide.

Show outer electrons only.

Pieces of zinc react with copper sulfate solution. Zinc sulfate solution is colourless.

Describe what you would see when an excess of zinc is added to copper sulfate solution and the mixture left until the reaction is complete.

This reaction is described as a redox reaction.

Explain, in terms of electrons, which particles have been oxidised and which particles have been reduced in this reaction.

The copper sulfate solution used has a concentration of 15.95 g dm⁻³.

Calculate the number of moles of copper sulfate, CuSO₄, in 50.00 cm³ of this solution. (relative atomic masses: O = 16, S = 32, Cu = 63.5)

number of moles of copper sulfate =_........ mol

In another experiment, 0.043 mol of copper sulfate, CuSO₄, is used.

Calculate, to one decimal place, the minimum mass of zinc that must be added to react with all the copper sulfate. (relative atomic mass: Zn = 65)

mass =_........ g

Most of the fuels used today are obtained from crude oil.

Which statement about crude oil is correct?

Crude oil is separated into several fractions by fractional distillation. Two of these fractions are kerosene and diesel oil.

State a use for each of these fractions.

kerosene_........

diesel oil_........

Figure 8 shows where the fractions kerosene and diesel oil are produced in the fractionating column.

Kerosene is obtained higher up the column than diesel oil. Kerosene and diesel oil fractions have slightly different properties.

Choose a property. State how this property for kerosene compares with the property for diesel oil.

property_........

comparison_........

Figure 9 shows the formulae of a molecule of butane and of a molecule of pentane. Butane and pentane are neighbouring members of the same homologous series.

Explain, using these formulae, why butane and pentane are neighbouring members of the same homologous series.

Butane has the formula C₄H₁₀.

Calculate the mass of carbon in 100 g of butane.

Give your answer to three significant figures.

(relative atomic masses: H = 1.00, C = 12.0; relative formula mass: C₄H₁₀ = 58.0)

You must show your working.

mass of carbon =_........ g

Butane burns completely in air to form carbon dioxide and water.

Write the word equation for this reaction.

Most of the fuels used today are obtained from crude oil.

Which statement about crude oil is correct?

Crude oil is separated into several fractions by fractional distillation. Two of these fractions are kerosene and diesel oil.

State a use for each of these fractions.

kerosene_........

diesel oil_........

Figure 1 shows where the fractions kerosene and diesel oil are produced in the fractionating column.

Kerosene is obtained higher up the column than diesel oil. Kerosene and diesel oil fractions have slightly different properties.

Choose a property. State how this property for kerosene compares with the property for diesel oil.

property_........

comparison_........

Figure 2 shows the formulae of a molecule of butane and of a molecule of pentane. Butane and pentane are neighbouring members of the same homologous series.

Explain, using these formulae, why butane and pentane are neighbouring members of the same homologous series.

Butane has the formula C₄H₁₀.

Calculate the mass of carbon in 100 g of butane.

Give your answer to three significant figures.

(relative atomic masses: H = 1.00, C = 12.0; relative formula mass: C₄H₁₀ = 58.0)

You must show your working.

mass of carbon =_........ g

The molecular formula of butene is C₄H₈.

Which of the following is the empirical formula of butene?

Calculate the relative formula mass of butene, C₄H₈.

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

relative formula mass_........

When burnt completely in air, butene forms carbon dioxide and water.

Balance the equation for this reaction by putting numbers in the spaces provided.

C₄H₈ + 6O_{2 ........} CO₂ +_........ H₂O

Describe the test to show that a gas is carbon dioxide.

Substance X is a gas at room temperature. It is a simple molecular, covalent substance.

Which row of the table shows the properties that substance X is most likely to have?

Diamond has a giant covalent structure.

State one property of diamond that is the result of its giant covalent structure.

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 9.

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 1.

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.