Chemistry Revision Cards

1. In the fractional distillation of crude oil, where is the hottest part of the fractionating column?

The bottom of the tower is between 350 and 400 ^oC and is the hottest part of the tower.

2. Which fraction leaves the tower at the very top?

Gases have a very low boiling point and do not condense at all, leaving the tower at the very top.

3. Which is a use for kerosene (paraffin)?

Kerosene is mainly used as fuel for aeroplanes.

4. Where do the longest hydrocarbon molecules condense?

The longest hydrocarbon molecules have the highest boiling points and condense at the bottom of the tower.

1. Which fractions are the hardest to ignite?

The longer the molecules, the harder it is to ignite the hydrocarbon.

2. Which is the main compound in natural gas?

Methane, CH₄, is the main compound in natural gas.

3. What was coal originally formed from?

Coal was formed from the remains of trees that were buried in such a way that they could not decompose normally.

4. What type of molecule is used as the starting point in cracking?

Cracking converts large hydrocarbon molecules into smaller and more useful hydrocarbons.

1. What conditions are used for cracking?

Cracking requires a high temperature and a catalyst.

2. What are the typical products of cracking?

Cracking tends to produce a mixture of small molecules, but there will usually be at least one alkene and at least one alkane.

1:What do depressants do?

Depressants such as alcohol slow down brain activity. They bind to receptor molecules needed to respond to neurotransmitters.

2:What sort of drug is caffeine?

Caffeine is a stimulant. It increases brain activity, causing more neurotransmitter molecules to diffuse across the synapse.

3:How are drugs produced?

Drugs can be produced from both natural and artificial sources.

4:Why are drugs tested on animals?

Drugs are tested on animals to check for side effects before moving on to clinical trials

1:What is a placebo?

A placebo is an inactive substance used in clinical trials. It is used as a control to see the effects of a drug.

2:In which sort of trial do the researchers know which group the volunteers are in, but the volunteers do not?

In a blind trial, only the researchers know which group the volunteers are in. This helps to reduce the effects of bias, where knowing which group you are in could affect the results

3:How do antibiotics work?

Antibiotics can stop bacteria from growing or reproducing. They are not effective against viruses

4:What is the addictive substance in tobacco smoke?

Nicotine is the addictive substance in tobacco smoke. It creates a dependency so that smokers become addicted.

1:Why does smoking increase the risk of coronary heart disease?

Tobacco smoke contains carbon monoxide, which reduces the ability of the blood to carry oxygen. This puts extra strain on the circulatory system.

2:What is a long term effect of excessive alcohol use?

Long-term effects of alcohol abuse include damage to the liver and brain. The liver is the organ that removes alcohol from the bloodstream.