Bulk & Surface Properties (AQA GCSE Chemistry)

This question is about silver nanoparticles. 

Silver can form cubic nanocrystals as shown in Figure 1 below.

Figure 1

A silver nanocrystal is a cube shaped nanoparticles with each side measuring 20 nm.

Calculate the surface area to volume ratio of the silver nanocrystal.

Silver nanoparticles are sometimes used in clothing to prevent odours.

Suggest why it is more economical to use nanoparticles of silver rather than coarse particles.

Particles are grouped into categories depending on their diameter.

Particle X has a diameter of  2.5 x 10^-7 m.

Which particle is this most likely to be?

A nanoparticle of a metal oxide is a cube. 

Each side has a length of 82 nm. 

What is the volume of the nanoparticle? 

Modern catalytic converters use nanosized particles of catalytic metals such as palladium and rhodium. 

Using nanosized particles is more cost effective than normal sized particles.

Suggest and explain why the use of nanosized catalyst particles reduces the production costs of catalytic converters.

Nanoparticles of magnesium oxide have antibacterial properties. 

Figure 1 below shows the percentage of bacteria killed. 

Figure 1

 Draw three conclusions from Figure 1.

Not all sizes of nanoparticles have points plotted.

Would including data for more sizes of nanoparticles improve the conclusions that can be drawn about their effect on killing bacteria?

Give a reason for your answer.

A coarse particle has a diameter of 1 × 10⁻⁶ m and a nanoparticle has a diameter of 1.6 × 10⁻⁹ m.

Calculate how many times larger the diameter of the coarse particle is than that of the nanoparticle.

This question is about nanoparticles and water.

Hydrogen and oxygen chemically combine to produce water molecules.

What type of bonding is present in a molecule of water.

Does pure water conduct electricity?

Give a reason for your answer.

Nanoparticles of cobalt oxide are used as a catalyst in the production of hydrogen from water. 

Compare the size of a nanoparticle with the size of an atom.

Explain why 1g of nanoparticles is a better catalyst than 1g of cobalt oxide powder.

Nanoparticles are used in medicine, and can be used to deliver drugs to the cells where they are needed.

Some people are concerned about using nanoparticles this way.

What is the main reason for this concern? 

Nanoparticles are useful substances with many applications.

Tick (✔) one use of nanoparticles.

How does the size of nanoparticles compare to normal-sized particles?

Draw a ring around the correct answer.

Tiny amounts of cerium oxide nanoparticles can be added to diesel fuel as a catalyst.

Why are only a tiny amount of cerium oxide nanoparticles used?

Explain how nanoparticles are able to catalyse reactions. 

Nanocrystalline metals are a new kind of metal structure which are based on nanoparticle science. 

Nanocrystalline metals are much harder and stronger than normal metals and their use in the production of artificial limbs is being investigated. 

Crystals in normal metal structures are around 20,000 nm in diameter. 

Explain how a metal and nanoparticles of the same metal can have different properties.

In terms of size, how do the crystals in nanocrystalline metals compare with the crystals in normal metals?

Hip joints are constantly moving when people move or walk during normal daily activities.

Suggest and explain why an artificial hip joint made of a nanocrystalline metal should last longer than one made from normal metals.

This question is about nanoparticles in products used for protection against the sun.

Explain why nanoparticles of titanium oxide are able to pass through the skin and travel around the body more easily than normal-sized particles of the same compound.

Give three reasons why sunscreens containing nanoparticles should be subjected to further testing.

Suggest why some companies that make sun creams might prefer to not engage in further testing.

Graphene is a single layer of graphite.

It can conduct electricity and can be used in loudspeakers.

Explain why graphene can conduct electricity. 

Explain why graphene is strong.

Explain why graphite can be used in the tips of pencils. 

This question is about nanoparticles and their uses.

Nanoparticles of platinum can be used in modern catalytic converters. 

Catalytic converters are found in car engines and prevent harmful substances that are produced when petrol burns from being released into the air. 

Figure 1 represents a platinum nanoparticle. 

All sides are the same length.

Figure 1

Calculate the surface area to volume ratio of this particle. 

Give your answer in the simplest whole number ratio.

Burning petrol in a car is an exothermic reaction.

Draw and label the reaction profile for an exothermic reaction in Figure 2.

Include labels for:

• Overall energy change

• Activation without a catalyst

• Activation energy with platinum catalyst

 Figure 2

Platinum is a transition metal. 

Describe the bonding and structure of platinum. 

Why is it cheaper to use nanoparticles of platinum as opposed to coarse particles of platinum? 

Processors in computers can be damaged if they are exposed to high levels of  heat.

To avoid this a heat sink is placed on top of the processor as shown in Figure 1.

A heat sink is a metal that conducts heat away from the processor.

Figure 1

Explain why the metal is a good conductor of heat.

Heat sinks are often made from copper, a transition metal.

Compare the properties of copper to the Group 1 metal, sodium.

Grease is used to fill the gaps between the processor and the heat sink.

Without the grease, the gaps contain air which is a poor conductor, so the grease improves the transfer of heat from the processor to the sink.

One manufacturer of thermal grease claims that grease containing nanosized particles of silver will help transfer the heat better than if fine particles were used.

How are nanosized particles different from fine particles?

Suggest one reason why fine particles of silver might not transfer heat as well as nanosized particles.

A gold nanoparticle is a cube with sides of 2 nm. 

What is the simplest surface area to volume ratio of the nanoparticle?