Relative formula mass

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.

The formula of a compound is X(OH)₂. X is an element found in Group 2 of the Periodic Table.

The relative formula mass of X(OH)₂ is 74.1.

Calculate the relative formula mass of one OH.

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

Use your answer to part (a) to calculate the relative atomic mass of X.

Use your answer to part (b) to identify X.

Use the Periodic Table on the Data Sheet.

A metal oxide has the formula X₂O, where X is a Group 1 metal.

The relative formula mass of the metal oxide is 94.2.

Relative atomic mass (A_r): O = 16.0

What is the name of X ?

A Lithium

B Potassium

C Rubidium

D Sodium

Zinc, Zn, reacts with sulfuric acid, H₂SO₄, to form the salt, ZnSO₄, and hydrogen.

Write the balanced symbol equation for the reaction of zinc with sulfuric acid.

Name the salt, ZnSO₄, made from zinc and sulfuric acid.

To make sure all the sulfuric acid reacts, an excess of zinc is used.

Describe how universal indicator could be used to show that all the sulfuric acid has reacted.

Calculate the relative formula mass of ZnSO₄.

Relative atomic mass (A_r): O = 16.0 S = 32.1 Zn = 65.4

Relative formula mass of ZnSO₄ =........

The percentage mass of an element in a compound can be calculated using the formula

Calculate the percentage mass of zinc in ZnSO₄.

Give your answer to 1 decimal place.

The reaction between zinc and sulfuric acid is exothermic.

Explain what is meant by an exothermic reaction.

The diagram shows the reaction profile for the reaction.

Label the activation energy on the diagram.

Explain the term activation energy.

The table shows the temperature changes in four reactions.

The reaction between zinc and sulfuric acid is slightly exothermic.

Which shows the reaction between zinc and dilute sulfuric acid?

Give a reason for your answer.

A metal oxide has the formula X₂O, where X is a Group 1 metal.

The relative formula mass of the metal oxide is 94.2.

Relative atomic mass (A_r): O = 16.0

What is the name of X ?

A Lithium

B Potassium

C Rubidium

D Sodium

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.

Copper can form many different compounds.

The table shows the formulae of five different compounds of copper.

Which compound, A, B, C, D or E, is made from copper, carbon and oxygen?

Which compound, A, B, C, D or E, is made when copper is oxidised as copper reacts with oxygen?

Which compound, A, B, C, D or E, reacts with dilute hydrochloric acid to make carbon dioxide?

Calculate the relative formula mass of compound D.

The relative atomic mass, A_r, of Cu is 63.5 and of S is 32.1

Which term is defined as ‘The sum of the relative atomic masses of all the atoms in a chemical formula’?

A Mass number

B Molecular formula

C Relative formula mass

D The Avogadro constant

A copper ore contains 66.4% copper. The ore is CuS.

What is the maximum mass of copper that can be extracted from 500 tonnes of the ore?

A 7.53 tonnes

B 66.4 tonnes

C 332 tonnes

D 33 200 tonnes

Relative atomic mass compares the average mass of an atom to which element?

A Carbon

B Hydrogen

C Nitrogen

D Oxygen

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

A student investigates how to make a sample of a pure salt.

His method is shown in Fig. 14.1.

React an excess of copper oxide with 50 cm³ dilute hydrochloric acid. Stage 1

Stage 2 Heat the solution from Stage 1.

Copper oxide is an insoluble compound that neutralises dilute hydrochloric acid.

Name the type of insoluble compound that neutralises an acid to form a salt and water.

Dilute hydrochloric acid is a hazardous chemical.

Describe one safety precaution the student should take when using dilute hydrochloric acid.

Stage 1 uses an excess of copper oxide.

Give a reason why.

Calculate the number of moles of copper oxide, CuO, in 0.500 g.

Give your answer to 3 significant figures.

Use your answer to (d)(i) and the balanced symbol equation to explain why the copper oxide is in excess.

Another student thinks that the method in Fig. 14.1 will not make pure copper chloride.

Explain why this student is correct.

What is the relative formula mass of sulfuric acid, H₂SO₄?

The relative atomic mass, A_r, of H is 1.0, of S is 32.1 and of O is 16.0.

A 49.1

B 81.2

C 98.1

D 129.2

Phosphorus sulfide, P₄S₃, has a relative formula mass of 220.3.

What is the percentage, by mass, of phosphorus in P₄S₃?

Use the Periodic Table to help you.

A 6.8

B 14.1

C 27.2

D 56.3

A student does an experiment to identify an unknown metal M.

The student weighs metal M. Then the student adds metal M to a solution of copper sulfate, CuSO₄(aq).

A reaction takes place forming copper metal, Cu:

The student separates the copper and then weighs the copper.

These are the student’s results: Mass of metal M = 8.10 g Mass of copper = 21.2 g

How could the student separate the copper from the solution?

Use your answer from (b)(i) and the Periodic Table to identify the metal M.

The reaction between sulfur dioxide and oxygen is reversible.

In a closed system the reaction between sulfur dioxide and oxygen reaches a dynamic equilibrium.

Use a symbol from the list to complete the sentence.

At equilibrium, the rate of the forward reaction is …….... the rate of the reverse reaction.

What is meant by the term reversible reaction ?

Name one source of sulfur dioxide in the atmosphere.

Describe two problems caused by the release of sulfur dioxide into the atmosphere.

The table shows some relative atomic masses.

Calculate the percentage, by mass, of oxygen in SO₂.

Give your answer to 1 decimal place.

The amount of sulfur dioxide released in the UK is decreasing.

This graph shows how it has decreased since 1970.

How much did the sulfur dioxide decrease between 1975 and 2015?

Sulfur dioxide decrease =........ kilotonnes

What is the mass of 2 moles of calcium hydroxide?

A 148.2 g

B 164.1 g

C 220.1 g

D 328.2 g