An investigation of neutralization reactions Essay -- GCSE Chemistry C

An investigation of neutralization reactions Aim Question : What is the effect of changing the concentration of an alkali, on the volume of acid needed to neutralise it, when acid is added to it? The plan is to use two acids (Hydrochloric & Sulphuric) and one alkali (Sodium Hydroxide). The reason I need to use two acids is; because the question applies to all acids and alkalis and to just use one of each would not enable me to come to a general conclusion. If there had been more time available, ideally I would have preferred to use two alkalis as well as two acids. Predictions First of all, here are the definitions for an acid and an alkali: An acid is a substance that forms hydrogen (H+) ions when placed in water. It can also be described as a proton donor as it provides H+ ions. An alkali is a soluble base and forms hydroxyl ions (OH-) when placed in water. It can be called a proton acceptor because it will accept hydrogen (H+) ions and form H2O. A Hydrochloric acid molecule (HCl) will release one H+ ion and one Cl- ion when placed in water. A Sodium Hydroxide molecule (NaOH) will release one Na+ ion and one OH- ion when placed in water. This means that one molecule of NaOH and one molecule of HCl will neutralise each other and produce H2O and a neutral salt called Sodium Chloride (NaCl). This means that to neutralise HCl and NaOH when they are at the same concentration, you need equal amounts of each. GRAPH On the other hand, a Sulphuric Acid molecule (H2SO4) will release two H+ ions and one SO4-- ions. This means that you need two molecules of NaOH to neutralise one molecule of H2SO4 and produce the neutral salt Sodium Sulphate (Na2SO4). This means ... ... in the following ways : * Instead of using Universal Indicator, I would use an indicator which only changed colour when the solution was Neutral rather than gradually changing as the pH became lower (e.g. Methyl Orange or Phenolphthalein). * To get the pH more accurate next time, a pH meter could be used. * To get it very accurate, the acids and alkalis supplied should be an exact amount (I am not sure whether the ones I used were exact). * To use very recently distilled water, because the water will become acidic if left for a long time. References Books Dunstan, S. 1968. Principles of Chemistry. Van Nostrand Reinhold  · Pages 187-88  · Pages 215- 253 McDuell, B. 1997. GCSE Chemistry Classbook. Letts  · Pages 171-72  · Pages 28-32  · Page 262 Computer programs Microsoft Excel Version 97 Microsoft Word 97 Paint Shop Pro 4