Chemistry Study Guide Acids and Alkalis

synergetic Science 2B Chapter Summary Chapter 10 ComMon mordants and Alkalis 10. 1 panes and Alkalis 1. Acids taste sour. more fruits demand vitriolics. 2. The three mineral demigods commonly found in the research laboratory ar hydrochloric acid, sulfuric acid and nitric acid. 3. Alkalis taste bitter and discover soapy or slippery. 4. The common cornerstones found in the laboratory are sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution and ammonia solution. 0. 2 Acid-Alkali Indicators 1. An acid-alkali indicator shows different colours in acids and alkalis. It stern be apply to discharge acids and alkalis. 2. Natural indicators potbelly be do from some deeply coloured floras. 3. Acids turn blue litmus report red whereas alkalis turn red litmus paper blue. Distilled water does not change the colour of litmus paper. It is a neutral substance. 4. The pH measure out shows the degree of acidity or alkalinity of a substance. 5. The pH value of a substance can be measured by using universal indicator, pH paper or a pH meter. 6.Low pH set mean high acidity (or low alkalinity). 7. High pH value mean high alkalinity (or low acidity). 8. Substances with pH values 7 sulphurous pH values = 7 neutral pH values 7alkaline. 10. 3 Acids and Corrosion 1. Dilute acids react with some metals and produce hydrogen. 2. sieve for hydrogen Put a burning splint near the blab out of a test tube containing the gas. If the gas is hydrogen, it burns with a pop sound. 3. The come in of reaction of some metals with dilute hydrochloric acid or dilute sulphuric acid maznesium zinc iron copper (no reaction) . Carbonates react with acids and give carbon dioxide. 5. stain and limestone mainly contain calcium carbonate. They are used as mental synthesis materials and they can be corroded by acids. 10. 4 Safety colligate to the Use of Acids and Alkalis 1. Strong acids / alkalis are corrosive. Weak acids / alkalis are generally less(p renominal) corrosive. 2. Dilute acids / alkalis contain a low percentage of acids / alkalis. Concentrated acids / alkalis contain a high percentage of acids / alkalis. 3. Concentrated strong acids and alkalis are super corrosive. 4. Safety measure in handling strong acids and alkalis Reason (a) follow the hazard upbraiding label corrosive on the surfaceTo warn users about the corrosive property of the chemicals. of the container. (b) Wear safety spectacles. To prevent the acids and alkalis from getting into the eye. (c) Put on protective gloves. To prevent our skin from contact with the acids or alkalis. (d) Wear laboratory coat. To prevent damage of clothing and body. (e) Work in a fume cupboard. To prevent vapours of the acids or alkalis from irritating our eyes and respiratory system. 5. To dilute a concentrated acid or alkali, forever add it slowly to a large amount of water with stirring. neer pour water into a concentrated acid or alkali. 6. The depression step in treating acid or alkali spillage on our body is to wash with plenty of water. 10. 5 Acid Rain 1. showy or normal rain has a pH value of 5. 6. 2. Acid rain has a pH value lower than 5. 6. 3.Practice testanswer keyAcid rain is mainly caused by the acidic pollutant gases sulphur dioxide and normality oxides. 4. The main sources of sulphur dioxide and nitrogen oxides in the air are motor vehicles, power stations and factories. 5. Acid rain may ? corrode structures make of metals, marble and limestone, ? kill fish and set ups in lakes and rivers, and ? slow down plant growth and even kill plants. 6. The government, industries and citizens should work together to reduce the acquit of sulphur dioxide and nitrogen oxides, which cause acid rain. 10. 6 Neutralisation 1. An alkali and an acid can neutralise each other. . Neutralisation occurs when an alkali is compound with an acid until the resulting solution becomes neutral (pH = 7). 3. When an acid is neutralised with an alkali, a sodium chloride and water are formed. The word equation for neutralisation is Alkali + Acid (Salt + Water 4. Antacids are weak alkalis used to neutralise excess acid in the stomach. 5. Weak acids, such as ethanoic acid in vinegar, can be used to neutralise the alkaline stings of wasps. 6. Weak alkalis, such as baking soda (sodium hydrogencarbonate), can be used to neutralise the acidic stings or bites of bees, ants and mosquitoes. . Weak alkalis, such as slaked lime (calcium hydroxide) and pulverised limestone, can be added to acidic soil to raise the pH for plant growth. 8. Acids in industrial wastes can be neutralised by adding alkalis such as sodium hydroxide, while alkalis can be neutralised by adding acids such as sulphuric acid. 10. 7 Daily Uses of Acids and Alkalis 1. Acids and alkalis can be used in cleaners to remove stains and grease. 2. Acids such as ethanoic acid can be used to preserve food. 3. Acids can be used to prevent the browning of fruits. pic pic