Atoms, elements & compounds

This question is about magnesium oxide.

What type of substance is magnesium oxide?

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Compound

Element

Mixture

Magnesium reacts with oxygen to produce magnesium oxide.

Balance the equation for the reaction.

What does the state symbol ‘(s)’ represent?

A student reacted magnesium with oxygen.

Figure 9 shows the apparatus used.

Figure 9

This is the method used.

1. Measure the mass of the empty crucible and lid.

2. Put magnesium into the crucible.

3. Measure the mass of the crucible, lid and magnesium.

4. Heat the crucible strongly.

5. Lift the lid occasionally.

6. Heat until the magnesium stops glowing.

7. Measure the mass of the crucible, lid and magnesium oxide.

Give one safety precaution the student should use.

The magnesium reacted with oxygen.

Suggest where the oxygen comes from.

The student lifted the lid several times.

Why did lifting the lid allow the magnesium to react completely?

Table 3 shows the results.

Calculate the mass of magnesium put into the crucible.

Use Table 3.

Calculate the mass of oxygen that reacted with the magnesium.

Use Table 3.

One use of carbon dioxide is in fizzy drinks.

In fizzy drinks carbon dioxide gas dissolves in water to form an aqueous solution of

The equation for the reaction is:

Complete the equation by writing the state symbol for carbonic acid (H₂CO₃).

Choose the answer from the box.

Which ion causes carbonic acid to be acidic?

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Describe how to test the pH of carbonic acid.

Give the result of the test.

Ammonia gas is produced from nitrogen gas and hydrogen gas in a reversible reaction.

The word equation is:

nitrogen + hydrogen ammonia

Figure 12 represents an ammonia molecule.

What is the formula of ammonia?

When does a reversible reaction reach dynamic equilibrium?

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Which condition is needed for the reversible reaction between nitrogen and hydrogen to be at dynamic equilibrium?

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How can the direction of a reversible reaction be changed?

Iron is used as a catalyst in the industrial production of ammonia.

Why is a catalyst used?

150 000 million kg of ammonia is produced each year.

85% of the ammonia produced each year is used to manufacture fertilisers.

Calculate the mass of ammonia used each year to manufacture fertilisers.

This question is about iron and steel.

Figure 4 shows a flow chart for the production of iron and steel from iron ore.

Iron ore consists mainly of iron oxide.

In the blast furnace iron oxide reacts with carbon monoxide to form iron and carbon dioxide.

Complete the equation for the reaction between iron oxide and carbon monoxide.

You should balance the equation.

Iron oxide is reduced in the reaction with carbon monoxide.

What does ‘reduced’ mean in this reaction?

Cast iron is an alloy.

Cast iron contains carbon.

Figure 5 shows the arrangement of atoms in pure iron and in cast iron.

Explain why cast iron is harder than pure iron.

In addition to cast iron, scrap steel is added to the steel-making furnace.

Give three environmental advantages of recycling scrap steel in this way.

This question is about hydrogen peroxide.

The formula of hydrogen peroxide is H₂O₂

Name the elements in a molecule of hydrogen peroxide.

How many atoms are in a molecule of hydrogen peroxide?

Hydrogen peroxide decomposes to produce oxygen and water.

Write the word equation for the reaction.

A student investigated the decomposition of hydrogen peroxide.

The student used manganese dioxide as a catalyst.

The student measured the volume of oxygen produced.

The student collected the oxygen in a gas syringe.

Figure 7 shows a gas syringe.

What is the volume of oxygen in the syringe?

Figure 8 shows how the volume of oxygen collected varied with time.

Which point on Figure 8 shows when the reaction is fastest?

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Which point on Figure 8 shows when the reaction has stopped?

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The student repeated the investigation using raw potato instead of manganese dioxide.

An enzyme in the potato acts as the catalyst.

Draw one line from each catalyst to the type of substance the catalyst is.

The student repeated the investigation using boiled potato instead of raw potato.

The enzyme in the boiled potato did not catalyse the reaction.

How will the rate of decomposition of hydrogen peroxide using boiled potato compare with the rate using raw potato?

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This question is about copper sulfate.

The formula of copper sulfate is CuSO₄

Table 5 shows information about the atoms in copper sulfate.

Complete Table 5.

Copper oxide and sulfuric acid react to produce copper sulfate and water.

Complete the word equation for this reaction.

What type of substance is copper oxide?

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A student planned to make blue copper sulfate crystals.

This is the method the student used.

1. Add 25 cm³ of dilute sulfuric acid to a conical flask.

2. Gently warm the dilute sulfuric acid.

3. Add 2 g of black copper oxide to the dilute sulfuric acid.

4. Stir the mixture.

5. Evaporate some of the water from the mixture using an electric heater.

6. Leave the mixture to cool.

Not all the copper oxide reacted. The student did not remove the excess copper oxide.

What would the product look like after step 6?

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The student should have filtered the mixture after step 4.

Draw a diagram of the apparatus the student could use.

You should label:

• the pieces of equipment used

• where the excess copper oxide collects.

What equipment should the student use to measure:

• 2 g of copper oxide

• 25 cm³ of dilute sulfuric acid?

Draw one line from each measurement to the most suitable piece of equipment.

1 g of copper sulfate is dissolved in water to make 25 cm³ of copper sulfate solution.

Calculate the concentration of the copper sulfate solution in g/dm³

This question is about Group 1 metals.

Figure 1 shows the melting points of Group 1 metals plotted against their atomic number.

Describe the trend shown by the melting points of Group 1 metals as the atomic number increases.

Determine the atomic number and melting point of caesium.

Use Figure 1.

Lithium is a Group 1 metal.

A lithium atom can be shown as.

How many electrons does the outer shell of a lithium atom contain?

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Lithium reacts with oxygen to produce lithium oxide.

Draw one line from each substance to the correct description of the substance.

Balance the equation for the reaction of lithium with oxygen.

What type of bonding is present in lithium oxide?

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Calculate the relative formula mass (M_r) of lithium oxide (Li₂O).

Relative atomic masses (A_r): Li = 7 O = 16

This question is about hydrogen chloride.

A hydrogen atom contains 1 electron and a chlorine atom contains 17 electrons.

Complete Figure 1 to show a dot and cross diagram for a hydrogen chloride molecule.

Show the outer electrons only.

Hydrogen gas (H₂) reacts with chlorine gas to produce hydrogen chloride.

Complete the balanced chemical equation for the reaction between hydrogen and chlorine.

Figure 2 shows the reaction profile diagram for the reaction between hydrogen and chlorine.

What do A and B represent on Figure 2 ?

How does the reaction profile diagram show that the reaction is exothermic?

Hydrogen chloride gas dissolves in water to form hydrochloric acid.

Hydrochloric acid contains hydrogen ions and chloride ions.

Explain why hydrogen chloride gas does not conduct electricity but hydrochloric acid is able to conduct electricity.