The screen of a flexible mobile phone needs a thin coating that is transparent, conducts electricity and does not crack when the screen is bent.
The table shows information about three possible coating materials.
| Material | Electrical conductivity | Percentage of light that passes through | Behaviour when bent | Cost and availability |
|---|---|---|---|---|
| indium tin oxide | good | 90 | brittle, cracks | expensive, indium is rare |
| graphene | very good | 97 | flexible and very strong | expensive to make in large sheets |
| poly(ethene) | does not conduct | 90 | flexible | cheap, made from crude oil |
Explain why poly(ethene) does not conduct electricity.
A layer of graphene is about 3.4 × 10-10 m thick. A flake of graphite is 0.17 mm thick. Calculate the number of graphene layers in the flake of graphite.
Evaluate the use of indium tin oxide, graphene and poly(ethene) as the coating for a flexible phone screen. Use the information in the table and your knowledge of structure and bonding.
48 exam-style questions on Edexcel GCSE Chemistry 2.5 Types of substance, covering 2.5.1 Classifying substances by structure and bonding, 2.5.2 Properties of ionic and simple molecular substances, 2.5.3 Giant covalent structures: diamond and graphite, 2.5.4 Fullerenes, graphene and simple polymers, 2.5.5 Properties of metals and non-metals, and 2.5.6 Limitations of bonding models and representations. Each one has a worked solution and a mark scheme showing where the marks go.