CHEMISTRY GUIDE

This page looks at the manufacture of epoxyethane from ethene, and then at some of the products that are made from epoxyethane. The manufacture of epoxyethane Conditions Temperature: about 250 - 300°C Pressure: about 15 atmospheres Catalyst: silver Problems and hazards during manufacture The main problem comes in controlling the temperature. The reaction is exothermic and so the temperature will tend to rise unless it is carefully controlled. At higher temperatures the ethene burns in the oxygen to produce carbon dioxide and water which means that the temperature would increase even more - and the whole thing get completely out of hand! Two hazards during manufacture come from the nature of epoxyethane. It is poisonous and carcinogenic (c...

This page looks at ways of swapping the -OH group in the -COOH group of a carboxylic acid for a chlorine atom. This produces useful compounds called acyl chlorides (acid chlorides). It covers the use of phosphorus(V) chloride and phosphorus(III) chloride as well as sulphur dichloride oxide (thionyl chloride). Replacing -OH by -Cl Introduction We are going to be looking at converting a carboxylic acid, RCOOH, into an acyl chloride, RCOCl. Acyl chlorides are also known as acid chlorides. By far the most commonly used example of the conversion of a carboxylic acid into an acyl chloride is ethanoic acid to ethanoyl chloride. Acyl chlorides are very reactive, and can be used to make a wide range of other things. That's why they are important. Note:   If you are want to find out more about acyl chlorides, you can ex...

This page looks at the simple reactions of carboxylic acids as acids, including their reactions with metals, metal hydroxides, carbonates and hydrogencarbonates, ammonia and amines. Note:   This page covers all the reactions likely to be asked by any of the UK syllabuses for 16 - 18 year olds, but no single syllabus is likely to want all of them. Check your syllabus and past papers to find out what you need to know. If you are a studying a UK-based syllabus and haven't got these, follow this link to find out how to get hold of them. The acidity of the carboxylic acids Why are carboxylic acids acidic? Using the definition of an acid as a "substance which donates protons (hydrogen ions) to other things", the carboxylic acids are acidic because of the hydrogen in the -COOH group. In solution in water, a hydrogen ion is transferred from the -COOH group to a water molecule. For exampl...

This page looks at how the equilibrium between a liquid (or a solid) and its vapour leads to the idea of a saturated vapour pressure. It also looks at how saturated vapour pressure varies with temperature, and the relationship between saturated vapour pressure and boiling point. The origin of saturated vapour pressure The evaporation of a liquid The average energy of the particles in a liquid is governed by the temperature. The higher the temperature, the higher the average energy. But within that average, some particles have energies higher than the average, and others have energies lower than the average. Some of the more energetic particles on the surface of the liquid can be moving fast enough to escape from the attractive forces holding the liquid together. They evaporate. The diagram shows a small region of a liquid near its surface. ...