Conservation of mass & balanced equations

2 24 g of magnesium reacts with oxygen to make 40 g of magnesium oxide.

What mass of magnesium oxide is made when 12 g of magnesium reacts?

A 20 g

B 24 g

C 36 g

D 40 g

The diagram shows a chemical reaction.

Why does the mass on the balance decrease during the reaction?

A A gas is produced.

B A liquid is produced.

C A solid is produced.

D A solution is produced.

Atoms are made up of protons, neutrons and electrons.

The table shows the relative mass and relative charge for a proton and electron.

Complete the table to show the relative mass and relative charge of a neutron.

Use numbers from the list.

The mass of a proton is 1.67 × 10^–27 kg. (b)

An electron is 0.0005 times lighter than a proton.

Calculate the mass of an electron in kg.

Give your answer in standard form.

The symbol for an atom of nitrogen is:

The table shows the number of protons in this atom of nitrogen.

Complete the table by writing in the number of neutrons and number of electrons.

Nitrogen reacts with hydrogen to form ammonia, NH₃.

This is the equation for the reaction.

What is the missing number that balances the equation?

Tick (✓) one box.

Calculate the relative formula mass, M_r, of ammonia, NH₃.

Relative atomic masses (A_r): H = 1 N = 14

A student thinks that the empirical formula of ammonia is NH₃.

Explain why the student is correct.

Tick (✓) one box.

Fig. 14.1 shows the ball and stick model for a molecule of ammonia.

Fig. 14.1

Which statements about a ball and stick model are true, and which are false ?

Tick (✓) one box in each row.

Fig. 14.2 shows the structure of a molecule of ammonia.

Fig. 14.2

Complete the dot and cross diagram for a molecule of ammonia.

Only show the outer shell electrons.

Hydrogen peroxide solution, H₂O₂(aq), decomposes to make water and oxygen gas.

Complete the balanced symbol equation for the reaction.

Describe a test and its result which shows that the gas produced in the reaction is oxygen.

Test........

Result........

A hydrogen peroxide solution produces oxygen gas slowly.

A student adds a piece of potato to the hydrogen peroxide solution. The potato contains a biological catalyst.

What name is given to biological catalysts?

Describe and explain the effect of adding the piece of potato to the hydrogen peroxide solution.

Include ideas about rate of reaction and activation energy.

The student measures the total volume of oxygen produced in the reaction with and without the piece of potato.

With the potato, the total volume is: increased, decreased, stays the same.

Tick (✓) one box.

The piece of potato added to the hydrogen peroxide solution is a six-sided cube.

Calculate the surface area of the piece of potato in cm². (i)

A student thinks that cutting the potato into smaller pieces will make the catalyst more effective.

Explain why the student is correct.

Tick (✓) one box.

The student measures the rate of reaction when the piece of potato is added to the hydrogen peroxide.

The rate of reaction is 1.5 cm³ / s.

They then measure the rate of reaction again with an increased concentration of hydrogen peroxide.

What would the rate of reaction be now?

Tick (✓) one box.

The diagram shows a chemical reaction.

During the reaction the mass on the balance decreases.

Which state symbol describes the product that causes the mass to decrease?

A aq

B g

C l

D s

Atoms are made from the sub-atomic particles protons, neutrons and electrons.

Table 12.1 shows the relative mass and relative charge of the three sub-atomic particles.

Complete Table 12.1 by writing the name of a sub-atomic particle in each space.

Table 12.1

An atom of phosphorus has an atomic number of 15 and a mass number of 31.

Calculate the number of protons, neutrons and electrons in this atom of phosphorus.

Phosphorus reacts with oxygen to form an oxide called phosphorus trioxide.

Phosphorus trioxide has the molecular formula P₄O₆.

What is the empirical formula of phosphorus trioxide?

Tick (✓) one box.

Complete the balanced symbol equation for the reaction of phosphorus trioxide with water.

Table 12.2 shows the melting point and boiling point of phosphorus trioxide.

Table 12.2

In the box draw the particle arrangement for phosphorus trioxide at 100 °C.

Hydrogen peroxide solution, H₂O₂(aq), decomposes to make water and oxygen gas.

Complete the balanced symbol equation for the reaction.

Describe a test and its result which shows that the gas produced in the reaction is oxygen.

Test........

Result........

A hydrogen peroxide solution produces oxygen gas slowly.

A student adds a piece of potato to the hydrogen peroxide solution. The potato contains a biological catalyst.

What name is given to biological catalysts?

Describe and explain the effect of adding the piece of potato to the hydrogen peroxide solution.

Include ideas about rate of reaction and activation energy.

The student measures the total volume of oxygen produced in the reaction with and without the piece of potato.

With the potato, the total volume is: increased, decreased, stays the same.

Tick (✓) one box.

The piece of potato added to the hydrogen peroxide solution is a six-sided cube.

Calculate the surface area of the piece of potato in cm². (i)

A student thinks that cutting the potato into smaller pieces will make the catalyst more effective.

Explain why the student is correct.

Tick (✓) one box.

The student measures the rate of reaction when the piece of potato is added to the hydrogen peroxide.

The rate of reaction is 1.5 cm³ / s.

They then measure the rate of reaction again with an increased concentration of hydrogen peroxide.

What would the rate of reaction be now?

Tick (✓) one box.

Lithium reacts with oxygen to form lithium oxide.

The symbols for lithium and oxygen on the Periodic Table are:

Explain how the positions of lithium and oxygen in the Periodic Table are used to decide that lithium is a metal and oxygen is a non-metal.

Use the Periodic Table on the Data Sheet.

Lithium reacts with oxygen to make lithium oxide.

Complete the balanced symbol equation for the reaction.

Write the electron arrangement for an atom of lithium.

A student thinks that sodium reacts in a similar way to lithium.

Explain why they are correct.

Use the Periodic Table on the Data Sheet.

Lithium can exist as two isotopes.

Explain what isotope means.

Lithium can be added to aluminium to make an alloy. One alloy contains 2% lithium.

A student draws a diagram of the alloy.

Calculate the percentage of lithium atoms in the alloy drawn by the student.

Suggest a reason why the student’s diagram is incorrect.

The word equation shows how iron is extracted from iron oxide.

The table shows the masses of the reactants and products.

What is the mass of iron produced?

A 1880 tonnes

B 2240 tonnes

C 2840 tonnes

D 4880 tonnes

Aluminium is extracted from a rock called bauxite which contains aluminium oxide.

The diagram shows information from a life-cycle assessment for the manufacture and use of aluminium products.

Give one reason why a life-cycle assessment is carried out.

Give two reasons why the products should be recycled at the end of their useful life.

18% of the bauxite rock is turned into aluminium.

Calculate the mass of aluminium that is extracted from 7500 kg of bauxite.

Give your answer to 2 significant figures.

Aluminium is extracted from aluminium oxide, Al₂O₃, by electrolysis.

This is the equation for the electrolysis of aluminium oxide.

A student thinks that this reaction is an example of reduction.

Explain why the student is correct.

Extracting aluminium by electrolysis is expensive.

Which statements about why the electrolysis is expensive are true, and which are false ?

Tick one (✓) box in each row.

It would be cheaper if aluminium could be extracted by heating the aluminium oxide with carbon.

Explain why aluminium oxide does not react with carbon.

The equation shows the reaction of zinc carbonate when it is heated.

• 5.0 g of zinc carbonate is heated in a test tube for 10 minutes.

• The mass of the test tube decreases by 0.6 g.

How does the law of conservation of mass explain this decrease in mass?

A 0.6 g of carbon dioxide is produced.

B 0.6 g of zinc oxide is produced.

C 4.4 g of carbon dioxide is produced.

D 5.6 g of zinc oxide is produced.

Lithium reacts with oxygen to form lithium oxide.

The symbols for lithium and oxygen on the Periodic Table are:

Explain how the positions of lithium and oxygen in the Periodic Table are used to decide that lithium is a metal and oxygen is a non-metal.

Use the Periodic Table on the Data Sheet.

Lithium reacts with oxygen to make lithium oxide.

Complete the balanced symbol equation for the reaction.

Write the electron arrangement for an atom of lithium.

When an atom of lithium reacts with oxygen it forms a lithium ion, Li +. (d)

Describe how an atom of lithium forms a lithium ion.

A student thinks that sodium reacts in a similar way to lithium.

Explain why they are correct.

Use the Periodic Table on the Data Sheet.

Lithium can exist as two isotopes.

Explain what isotope means.

Lithium can be added to aluminium to make an alloy. One alloy contains 2% lithium.

A student draws a diagram of the alloy.

Calculate the percentage of lithium atoms in the alloy drawn by the student.

Suggest a reason why the student’s diagram is incorrect.

Describe what happens when solid potassium bromide is heated up until it melts into a liquid.

Use ideas about the particle model.

Explain why potassium bromide must be molten for electrolysis to happen.

State the product made at the cathode and write the half equation for the reaction.

The electrolysis is repeated with a solution of potassium bromide.

A student thinks that the same product will be formed at the cathode.

Explain why the student is incorrect.

Name of the different product formed........

Fluorine gas reacts with sodium to form sodium fluoride.

What is the balanced half equation for the reaction of fluorine when it reacts with sodium?

Aluminium is extracted from a rock called bauxite which contains aluminium oxide.

The diagram shows information from a life-cycle assessment for the manufacture and use of aluminium products.

Give one reason why a life-cycle assessment is carried out.

Give two reasons why the products should be recycled at the end of their useful life.

18% of the bauxite rock is turned into aluminium.

Calculate the mass of aluminium that is extracted from 7500 kg of bauxite.

Give your answer to 2 significant figures.

Aluminium is extracted from aluminium oxide, Al₂O₃, by electrolysis.

This is the equation for the electrolysis of aluminium oxide.

A student thinks that this reaction is an example of reduction.

Explain why the student is correct.

Extracting aluminium by electrolysis is expensive.

Which statements about why the electrolysis is expensive are true, and which are false ?

Tick one (✓) box in each row.

It would be cheaper if aluminium could be extracted by heating the aluminium oxide with carbon.

Explain why aluminium oxide does not react with carbon.

Calculate the lowest initial temperature of the copper sulfate solution.

Use the student’s results to list the metals in the order of reactivity obtained by the student.

The student’s results put the reactivity of iron and tin in the incorrect order.

The student thinks that the error could be because they added incorrect masses of each metal.

What piece of equipment could the student use to get a more accurate measurement of the mass of each metal?

Another student thinks that the error could be because the iron powder used is old and its surface has been oxidised.

Describe and explain how this oxidation could have affected the results for iron.

The balanced symbol equation for the reaction between magnesium and copper sulfate solution is:

The reaction can be written as an ionic equation.

Complete the balanced ionic equation for the reaction.

The law of conservation of mass states that the total mass stays the same during a chemical reaction.

Which is an explanation for the law of conservation of mass?

A All the atoms in a chemical reaction are the same size.

B All the atoms in a chemical reaction have the same mass.

C No atoms are created or destroyed during a chemical reaction.

D The atoms of each reactant and product have the same mass.

In industry, iron can be extracted from iron ore. Iron ore contains iron oxide, Fe₂O₃.

Iron is extracted from iron oxide by reduction.

The equation for one reaction is

Complete the balanced symbol equation for the reaction.

Why does this reaction happen?

Tick (✓) one box.

Explain how the equation shows that the iron oxide is reduced.

Which chemical reduces the iron oxide, Fe₂O₃?

Tick (✓) one box.

In industry, iron is extracted from iron ore in a blast furnace.

The table shows information about the production of iron in a blast furnace and from recycling.

Give two reasons why it is better to produce iron from recycling than in a blast furnace.

Use the information from the table.

Calculate the mass of iron made from 250 tonnes of iron ore in the blast furnace. Give your answer in kilograms.

(1 tonne = 1000 kg)

Lead, Pb, and dilute nitric acid, HNO₃ react.

Which row correctly balances the equation?

Iodine is an element in Group 7 of the Periodic Table.

Seaweed has small amounts of compounds containing iodine. It is possible to extract iodine from seaweed.

The diagram shows the stages in the extraction of iodine.

In Stage 1 iodide ions are produced by reduction.

Explain reduction in terms of electrons.

In Stage 2 iodide ions are oxidised to iodine.

Complete the half-equation for the oxidation of iodide ions into iodine.

In Stage 3 if the solution is heated for too long, iodine vapour is formed.

What colour is iodine vapour?

0.13 g of iodine is produced from 5.0 g of seaweed.

Calculate the percentage mass of iodine in the seaweed.

Complete each sentence to describe the formation of nitrogen dioxide.

Use the words or phrases in the list.

The molecules of nitrogen and oxygen........

The atoms then........ to form nitrogen dioxide.

This is called a........

The equation shows the formation of nitrogen dioxide.

Complete the balanced symbol equation for the reaction.

Use Fig. 11.1.

The table shows the melting point and boiling point of pure nitrogen dioxide.

Which state symbol shows the physical state of nitrogen dioxide at –2 °C?

Tick (✓) one box.

A scientist measures the melting point of a sample of nitrogen dioxide.

The result shows that the sample of nitrogen dioxide is impure.

Which temperature could be the melting point of the impure nitrogen dioxide?

Tick (✓) one box.

A molecule of nitrogen dioxide has the formula NO₂.

Calculate the relative formula mass for nitrogen dioxide.

Relative atomic mass (A_r): N = 14.0 O = 16.0

Nitrogen dioxide is made from the reaction of nitrogen with oxygen.

Fig. 11.2 shows the bonding in a molecule of oxygen, O₂.

Fig. 11.2

Fig. 11.3 shows an incomplete dot and cross diagram for oxygen.

Fig. 11.3

Complete Fig. 11.3 to show the arrangement of the electrons in a molecule of oxygen.

A student investigates how the mass changes as magnesium reacts with excess dilute sulfuric acid.

The diagram shows the apparatus they use.

The student measures the mass every minute for 8 minutes.

Table 13.1 shows their results.

Table 13.1

Complete the table with an estimate of the missing mass at 3 minutes.

Write your answer in the box in Table 13.1.

The student thinks that the results show that all the magnesium had reacted.

Explain why the student is correct. Use data from Table 13.1.

The student repeats the experiment three times.

Table 13.2 shows the results of the three experiments at 1 minute.

Table 13.2

Calculate the mean mass in the three experiments.

Give your answer to 1 decimal place.

The ionic equation shows the reaction of chlorine, Cl₂, with sodium bromide, NaBr.

What is the simplest ionic equation for this reaction?

Calcium is a metal found in Group 2 of the Periodic Table.

Draw the arrangement of electrons in an atom of calcium.

Calcium is a metal which can conduct electricity.

Describe the structure and bonding in a metal and explain why metals can conduct electricity.

You can include a diagram in your answer.

Calcium reacts with water to form a solution of calcium hydroxide, Ca(OH)₂, and hydrogen.

Write the balanced symbol equation for the reaction of calcium with water.

Include state symbols in your equation.

A solution of calcium hydroxide is also called limewater.

Name the gas limewater is used as a test for.

Calculate the number of moles in 1.88 g of calcium hydroxide.

Give your answer to 2 significant figures.

Relative atomic mass (A_r): H = 1.0 O = 16.0 Ca = 40.1

Use your answer to part (d)(i) to calculate the concentration of calcium hydroxide in the solution formed.

Give your answer in mol / dm³.

Concentration of solution =........ mol / dm³

A student adds an excess of dilute hydrochloric acid, HC l, to a solution of calcium hydroxide, Ca(OH)₂.

Write the balanced ionic equation for the reaction of dilute hydrochloric acid and a solution of calcium hydroxide.

Describe and explain how the pH of the solution of calcium hydroxide changes as the dilute hydrochloric acid is added until it is in excess.

Colour changes can be used to show that oxidation and reduction happen in chemical reactions.

The diagram shows the reaction between an acidic solution of vanadium(IV) oxide and zinc.

• As the reaction happens the colour of the solution turns from blue to green.

The balanced half equation shows the reaction of vanadium(IV) oxide.

A student thinks that the half equation shows that reduction has taken place.

Describe two ways in which the half equation shows the student is correct.

This half equation shows the reaction of the zinc.

Complete the half equation for the reaction.

The student removes the zinc from the green solution by filtration. When they add some nitric acid to this solution it turns back from green to blue.

What is the role of the dilute nitric acid in this reaction?

Tick one (✓) box.

The equation shows the extraction of iron, Fe, from an oxide of iron, X, using carbon, C.

2X + 3C → 4Fe + 3CO₂

What is the formula of X ?

A FeO

B Fe₂O

C Fe₂O₃

D Fe₄O₆

A student investigates the rate of reaction between large pieces of calcium carbonate and dilute hydrochloric acid.

Fig. 13.1 shows two different experiments the student could use. In both experiments the mass decreases as the reaction progresses.

Fig. 13.1

The equation shows the reaction between calcium carbonate and hydrochloric acid.

Use this equation to explain why the mass decreases as the reaction progresses.

The student decides to use Experiment 2 because they think it will produce more accurate results than Experiment 1.

Explain why the student is correct.

The student repeats Experiment 2 with smaller pieces of calcium carbonate to see how this changes the rate of the reaction.

Describe two variables the student must keep the same in this experiment.

Describe and explain the effect of using smaller pieces of calcium carbonate on the rate of the reaction.

Which equation shows that the mass of the solid decreases as the solid reacts?

Iron oxide, Fe₂O₃, is heated with carbon, C. Iron, Fe, and another product, X, are made. Look at the equation for the reaction.

What is the formula of X ?

A CO

B CO₂

C FeCO₃

D O₂

Complete the balanced symbol equation for the reaction of sodium and chlorine to make sodium chloride.

Sodium chloride has a high melting point.

Explain why.

Use ideas about the structure and bonding in sodium chloride in your answer.

Write in the table the state symbol for the solution of sodium chloride.

Tick (✓) one box in each column of the table to show if solid sodium chloride and a

solution of sodium chloride conduct electricity.

Complete the table by writing in the explanation for the student’s results.

Use ideas about the structure and bonding in sodium chloride in your answer.

Sodium reacts with water to form sodium hydroxide and hydrogen.

What is the correctly balanced symbol equation for this reaction?

A student investigates heating hydrated copper(II) sulfate, CuSO₄.5H₂O.

The diagram shows the experiment they do.

The student:

• Measures the mass of a boiling tube.

• Puts about 5 g of hydrated copper(II) sulfate in the boiling tube and measures the mass.

• Gently heats the boiling tube for one minute.

• Lets the boiling tube cool down and measures the mass.

During the experiment the hydrated copper(II) sulfate turns from blue to white and water vapour is produced.

Look at the student’s results.

Calculate the mass of water produced in the experiment.

The student expected a greater mass of water to be produced.

How could they improve the experiment so a greater mass of water vapour is produced?

Complete and balance the symbol equation.

The student adds a few drops of water to a boiling tube containing some of the white solid.

Describe what the student observes happening to the white solid.

Give a reason for your answer.

Observation........

Reason........

As water reacts with the white solid, the temperature of the boiling tube increases.

What name is given to this type of reaction where heat is transferred to the surroundings?

Aluminium is produced from aluminium oxide by electrolysis.

The diagram shows the industrial electrolysis of aluminium oxide.

Look at the equation for the electrolysis of aluminium oxide.

Complete the balanced symbol equation for the reaction.

Molten aluminium oxide contains Al³⁺ and O²⁻ ions. (b)

Explain why the aluminium oxide must be molten during electrolysis.

Explain why aluminium is produced at the cathode.

Aluminium melts at 650 °C.

Describe two reasons why it is cheaper to recycle aluminium than to produce it from electrolysis.

The equation shows the reaction for the cracking of the alkane C₁₅H₃₂.

What is the formula of X ?

A C₃H₆

B C₃H₈

C C₅H₁₀

D C₅H₁₂

Look at the equations.

They show the two half equations that happen during the electrolysis of molten sodium chloride.

What is the correctly balanced equation for the electrolysis of molten sodium chloride?

Crude oil is a mixture of alkanes which can be separated into different fractions.

The different fractions have a range of different boiling points.

The diagram shows the process of fractional distillation.

Explain how fractional distillation separates the crude oil into fractions.

Icosane, C₂₀H₄₂, is an alkane found in one of the fractions.

It has a boiling point of 343 °C.

Which fraction, A, B, C, D, E or F, contains icosane?

Icosane is converted into more useful products by cracking.

State the two conditions used for cracking.

Many different products can form when cracking icosane.

In one reaction, a molecule of icosane (C₂₀H₄₂) forms a molecule of hydrogen, H₂, and one other product.

Write the balanced symbol equation for this reaction.

* Fraction A contains the alkanes methane, ethane, propane and butane.

Table 14.1 shows some information about these four alkanes.

Describe and explain the similarities and differences in the boiling point of these four alkanes.

Use information in Table 14.1 and your knowledge of structure and bonding in your answer.

Copper can be produced from a copper(II) sulfate solution by electrolysis.

A student investigates how the mass of copper produced changes with the size of the current used during the electrolysis. The student varies the current used during electrolysis and investigates the mass of copper produced at the cathode.

The diagram shows the apparatus they use.

Copper(II) sulfate solution

The student:

• Measures the mass of the dry cathode at the start of the experiment.

• Switches the power pack on for 10 minutes.

• Removes the cathode and washes it with water.

• Dries the cathode.

• Measures the mass of the cathode again.

• Calculates the mass of copper formed at the cathode.

The student repeats the experiment at different currents.

They plot a graph of their results.

The copper(II) sulfate solution contains copper ions, Cu²⁺. (a)

Write the balanced half equation for the formation of copper at the cathode.

Include state symbols in the equation.

Look at the graph.

The student decides that the result for the mass of copper formed at the cathode at 2 A is incorrect.

Give a reason for this result.

Has the student drawn the correct line of best fit?

Give a reason for your answer.

Explain how repeating the experiment could improve the accuracy of the results.

Use the graph to calculate the mass of copper produced by a current of 15 A.

Give your answer to 1 significant figure.

Which ionic equation is balanced correctly?

This question is about compounds of magnesium.

Magnesium hydroxide contains magnesium ions, Mg²⁺, and hydroxide ions, OH^–. (a)

Write the formula of magnesium hydroxide.

Magnesium carbonate, MgCO₃, reacts with dilute hydrochloric acid, HCl.

Magnesium chloride, MgCl₂, water and carbon dioxide are made.

Write the balanced symbol equation for the reaction.

A compound of magnesium contains an unknown element, X.

X is an element found in Group 7 of the Periodic Table.

The compound has the formula MgX₂.

The relative formula mass of the MgX₂ is 184.1.

Calculate the relative atomic mass of X. A_r Mg = 24.3

Phosphoric acid, H₃PO₄, is a strong acid.

A student investigates how the pH of a solution of dilute phosphoric acid changes when a solution of calcium hydroxide is slowly added to it from a burette.

The student then calculates the concentration of hydrogen ions as the pH changes.

Table 16.1 shows the results of her experiment.

Explain why phosphoric acid is described as a strong acid.

Explain why the solution of phosphoric acid used is described as dilute.

Complete the balanced symbol equation for the reaction between phosphoric acid and calcium hydroxide.

Explain the term electrolysis.

Electrolysis involves the reactions of cations and anions.

Describe the difference between cations and anions.

The electrolysis of molten potassium chloride makes potassium at the cathode.

Write the balanced half equation for the formation of potassium.

State and explain if this equation shows oxidation or reduction.

Name the product formed at the anode when an aqueous solution of potassium chloride, KC l (aq), is electrolysed.

Give a reason for your answer.

The diagram shows what happens when a small amount of potassium bromide solution, KBr, is added to a solution of chlorine, Cl₂.

Write the balanced symbol equation for the reaction between potassium bromide, KBr, and chlorine, Cl₂.

Write down the name of the chemical which makes the solution orange.

In this reaction is chlorine oxidised or reduced?

Explain your answer.

Explain why chlorine is more reactive than bromine.

Calcium carbonate, CaCO₃, decomposes when heated. Calcium oxide, CaO, and carbon dioxide, CO₂, are made.

Look at the equation for the reaction.

In an experiment, 20.0 g of CaCO₃ are used. 11.2 g of CaO are made.

What is the mass of CO₂ made?

A 8.8 g

B 11.2 g

C 20.0 g

D 31.2 g

A student tests three solutions A, B and C. He wants to identify which solution is acidic.

The student adds a metal carbonate to each solution.

Table 13.1 shows his results.

Which solution, A, B or C, is acidic?

Tick (✓) one box.

Suggest a pH value for the acidic solution.

Write down two other tests the student could use to identify that the solution is acidic.

The student adds the acidic solution to a solution of sodium hydroxide. A neutralisation reaction takes place.

He records the pH of the mixture.

Table 13.2 shows his results.

Describe the relationship between the volume of acidic solution added and the pH of the mixture.

Sodium hydroxide is an alkali.

Which ion do solutions of alkalis contain?

H⁺ Na⁺ OH^– SO₄^2–

In a different neutralisation reaction sulfuric acid, H₂SO₄, reacts with sodium hydroxide, NaOH.

Complete the balanced symbol equation for this reaction.

This question is about Group 1 and Group 7 elements.

A Group 1 element D reacts with water.

This is the equation:

Name element D.

A teacher shows this reaction to his class.

Describe one safety precaution he should use.

E is a colourless gas.

How can you show if the gas is hydrogen or oxygen?

Describe the tests for hydrogen and oxygen, and the results you would expect with gas E.

test for hydrogen........

result with gas E........

result with gas E........

Group 1 elements are very reactive.

Write down the reason why.

Table 11.1 shows the densities of the first four Group 1 elements at room temperature_.

Calculate how many times larger the density of rubidium is than the density of lithium

Give your answer to 1 significant figure.

1 g of sodium and 1 g of potassium are mixed to form an alloy.

Calculate the density of the alloy.

Density =........ g / cm³

The element caesium (Cs) is also in Group 1. Caesium is found below rubidium in the Periodic Table.

Use the information in Table 11.1 and your knowledge of trends in properties for Group 1 elements to estimate the density of caesium.

Density of caesium =........ g / cm³

A student reacts a solution of KBr with chlorine, Cl₂.

Balance the equation for this reaction.

What is the name of the chemical KBr?

Tick (✓) one box.

What does the reaction tell you about the reactivity of Br₂ and Cl₂?

Explain your answer.

One homologous series of organic compounds is called the alkanes.

They have the general formula C_nH_2n+2.

The alkane with one carbon atom, n = 1, is called methane.

Write down the formula of methane.

Table 13.1 shows the energy released when some alkanes burn in oxygen.

Plot a graph of number of carbon atoms against energy released using the data in Table 13.1 and draw a line of best fit.

Use the graph to predict the energy released when methane burns (1 carbon atom).

Energy released =........ kJ / mol

Hexane is a liquid alkane that burns in oxygen.

Which element in hexane is oxidised to produce water?

Give a reason for your answer.

A student burns 10.0 g of hexane.

These are his results.

Mass of hexane before burning = 10.0 g Mass of hexane after burning = 0.0 g

The law of conservation of mass is true for this reaction.

Explain why.

Magnesium ions react with chloride ions to form magnesium chloride.

What is the correct ionic equation for this reaction?

Brine is the name given to the solution formed when sodium chloride, NaC l, dissolves in water.

During the electrolysis of sodium chloride solution, two ions are attracted to the negative electrode (cathode).

Identify the two ions attracted to the negative electrode (cathode).

State and explain which product is formed at the negative electrode (cathode).

Use the results to place the metals in order of reactivity.

Most reactive metal........

Least reactive metal........

Explain your reasoning.

Write a word equation for the reaction between copper and silver nitrate solution.

Look at the information about three elements X, Y and Z in the Periodic Table.

* Student A thinks that elements X, Y and Z are in the same Group of the Periodic Table.

Student B thinks they are in different Groups of the Periodic Table.

Analyse and explain the information in the table that supports both Student A’s and Student B’s conclusions.

Who do you think is correct?

Write a balanced symbol equation for the reaction of element Y with water.

Use ‘ Y ’ to represent element Y.

Aluminium oxide is mixed with cryolite in the electrolysis cell.

Explain why cryolite is used.

Aluminium is made at the negative electrode (cathode) from aluminium ions, Al³⁺.

Write a half equation for this reaction. Use e⁻ to represent an electron.

Oxygen, O₂, is made at the positive electrode (anode).

The anodes in the cell have to be replaced every few weeks.

Suggest why.

Write the overall balanced symbol equation for the electrolytic breakdown of aluminium oxide, Al₂O₃.