Chemistry Essay

260 WordsOct 16, 20112 Pages
Compare qualitative and quantitative analysis Qualitative analysis: involves the determining of species present in a sample and is data in word form Quantitative analysis: involves the determining of amounts or concentration of specific substances and is numerical data Compare destructive and non-destructive testing Destructive: is when the composition of the testing solution is altered by the chemical additive and hence the original sample is not recoverable. E.g. testing pH of a sample using an indicator. Non-destructive: is when the composition of the testing solution is not altered and the original sample can be reused after testing. E.g. testing pH of a sample using a pH meter. Describe qualitative and/or quantitative tests for hardness, turbidity, and acidity (pH) in order to analyse and compare the quality of water samples Hardness: • Hardness is due to the presence of significant concentrations of calcium and magnesium ions in the water. • Hard water is water that does not lather with soap and which leaves a grey scum around baths and basins; if the water is not ‘hard'(and with very low concentrations of calcium and magnesium), then it is called soft water. • Ca2+(aq) + 2C17H35COO-(aq)  Ca(C17H35COO)2(s). The precipitate is also written as (C17H35COO)2Ca • Mg2+(aq) + 2C17H35COO- (aq)  Mg(C17H35COO)2 (s) • Qualitative: high levels of Ca2+ and Mg2+ ions make the water hard. This means soap doesn’t lather (form froth). Sydney water is identified as soft water as its hardness lies between 10 – 40 ppm. Soft water: < 75 ppm Hard water: 150 – 500

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