Properties of Materials (OCR GCSE Chemistry A (Gateway))

Look at the diagram. It shows the displayed formula of succinic acid.

Complete the table to show the number of atoms of each element in this displayed formula.

What is the empirical formula of succinic acid?

Succinic acid has a melting point of 184°C and a boiling point of 235°C.

What is the state of succinic acid at 25°C?

Explain your answer.

A new solid, compound X, has been discovered. Scientists investigated the effect of heat on compound X.

Look at the graph. It shows how the state of compound X changes as it is heated.

i) What is the melting point of compound X?

Melting point = ................................................. °C[1]

ii) A scientist describes compound X as a pure substance.

Explain what scientists mean when they describe compounds as pure.

[1]

iii) Explain how the scientists tell from the graph that compound X is a pure substance.

[1]

Scientists find out some more information about compound X.

Describe and explain the type of bonding found in compound X.

Use all the information above to justify your answer.

The diagrams show three different structures of carbon.

i) What is the name of structure Y?

[1]

ii) Diamond can be described as having a giant lattice structure.

Why is diamond described as a giant lattice structure?

[2]

i) Diamond is the hardest naturally occurring substance on Earth.

Explain why diamond is hard.

[2]

ii) Graphite is used in pencils. Graphite is a soft material.

Explain why graphite is soft.

[1]

Graphene is another substance made of carbon atoms. Graphene is a single layer of graphite.

It is just one atom thick. Graphene can be used to make touchscreens for electronic devices.

Look at the table. It shows some properties of graphite and graphene.

Explain why graphene is suitable for making touchscreens.

Use the information from the table.

i) Carbon reacts with hydrogen to make methane, CH₄.

Complete the dot and cross diagram to show the bonding in methane.

[2]

ii) Methane has a low melting point.

Explain why methane has a low melting point.

Use ideas about structure and bonding in your answer.

[2]

Look at the data about some hydrocarbons.

Butane contains 4 carbon atoms.

Use the table to suggest the molecular formula of butane.

The boiling points of ethane and propane have been plotted on the graph.

i) Plot the boiling points for pentane and hexane on the graph.

Draw the line of best fit.

[2]

ii) Use your graph to estimate the boiling point of butane.

[1]

Answer: …………………………………. °C

iii) Describe the relationship between the number of carbon atoms in a molecule and its boiling point.

Use ideas about forces between molecules to explain your answer.

[2]

Propane burns in oxygen, O₂.

Carbon dioxide and water are made.

Write a balanced symbol equation for this reaction.

Propane gives out 50 000 J/g when it reacts with oxygen.

• A propane burner is used to boil water to make a cup of tea.

• 63 000 J of energy are needed to boil the water.

• There is only 3 g of propane in the burner.

Do a calculation to find out if there is enough propane in the burner to boil the water.

Nanoparticles are used as catalysts.

Describe a property of nanoparticles that make them useful as catalysts.

A student is synthesising a new titanium dioxide (TiO₂) nanoparticle for use as a catalyst.

One TiO₂ nanoparticle has a mass of 5.0 × 10^–3 mg.

Calculate how many TiO₂ nanoparticles are in 80.0 mg of TiO₂.

Lithium is a metal found in Group 1 of the Periodic Table.

i) Describe the structure and bonding in a metal.

You may include a diagram in your answer.

[2]

ii) Lithium is malleable even though metallic bonds are strong.

Explain why metals are malleable.

[1]

iii) Lithium can conduct electricity in the solid and liquid state.

Explain why metals can conduct electricity.

[2]

An alloy is a mixture of a metal with one or more other elements.

When lithium is mixed with aluminium it makes an alloy that can be used in aircraft.

Adding different amounts of lithium to the aluminium changes the properties of the alloy.

A scientist thinks that alloy C is best for making an aircraft.

Is she correct?

Explain your answer using evidence from the table.

The scientist uses the particle model to show the elements present in alloy B.

i) Calculate the percentage of lithium atoms in the diagram of alloy B.

Percentage of lithium atoms = ..................................................... %

[1]

ii) Use your answer to part (c)(i) to explain if the diagram accurately shows the structure of alloy B.

[1]

A new sun cream has been developed using zinc oxide nanoparticles.

The small particles provide better protection from the sun and they do not leave white marks on the skin.

Explain one possible risk of using nanoparticles in sun cream.

A cube-shaped nanoparticle has sides of length 50nm.

Calculate the surface area to volume ratio for this nanoparticle. Use the equation: ratio = surface area ÷ volume

Surface area to volume ratio = ...................................................

i) Scientists compare the size of nanoparticles to the sizes of other small objects.

Look at the table.

The diameter of a DNA strand is 2.5nm.

Explain why DNA is a nanoparticle but a water molecule is not a nanoparticle.

[2]

ii) Calculate how many zinc oxide nanoparticles would fit across a human hair.

Give your answer to 2 significant figures.

Number of nanoparticles = ............................................. [2]

The diagrams show the structures of two forms of carbon.

• Graphite is a good conductor of electricity.

• Diamond does not conduct electricity.

Use ideas about structure and bonding in diamond and graphite to explain these observations.

Carbon can form many thousands of different compounds.

Two examples are shown below.

Why can carbon form many thousands of different compounds?

Ethanol contains carbon.

Look at some information about ethanol.

• Melting point = –114 °C

• Boiling point = 78 °C

Predict the state of ethanol at 25 °C. How can you tell?

A student is measuring the boiling point of some liquids.

She measures the boiling point of water, petrol and ethanol.

The student’s method is not safe.

Explain why it is not safe and explain how she could improve her method to make it safer.

The student looks up some data on melting points and boiling points.

Complete the table to show the states of propane and hexane at 25 °C.

Propane burns in oxygen, O₂. Carbon dioxide and water are made.

Write a balanced symbol equation for this reaction.

Look at the diagrams of sodium chloride and water.

Sodium chloride has a melting point of 801 °C.

Use the diagram of sodium chloride to explain why.

Water has a low melting point and boiling point.

Explain why.

Magnesium oxide has a similar structure to sodium chloride.

Draw ‘dot and cross’ diagrams to show the ionic bonding in magnesium oxide.

• Include the charges on the ions.

• The electronic structure of magnesium is 2.8.2.

• The electronic structure of oxygen is 2.6.

Look at the data about some substances.

What is the type of bonding present in each of substances A, B and C?

Explain how you can tell.

Look at the data about some substances

Explain the type of bonding present in each substance A, B and C.

Relate the type of bonding to the properties of each substance.