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Unit 10 Summary check - point

Learn about the properties, uses, and safety measures related to acids and alkalis. Explore their effects on daily life, laboratory experiments, and the environment.

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Unit 10 Summary check - point

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  1. Unit 10 Summary check-point

  2. 10.1 p.57 Acids & alkalis in daily life 1 Acids taste ______ (a) but alkalis taste ______ (b) . sour bitter 2 The colour of red cabbage extract is ______(a) in acids & ________ (b) in alkalis. red green

  3. 3 Some plant extracts contain pigments that can change colour in acids & alkalis. They can be used as ______________________ (a) . natural indicators

  4. 10.2 Laboratory acids & alkalis 4 The commonly used laboratory _________ (a) include hydrochloric acid, nitric acid and sulphuric acid. The commonly used laboratory __________ (b) include sodium hydroxide & ammonia solution.  acids alkalis

  5. 5 We should take the necessary ___________________ (a) when handling acids & alkalis. We must use them carefully.  p.58 safety precautions 6 Common indicators used in the laboratory are_________ (a) & __________________ (b) .  litmus universal indicator

  6. 7 Blue litmus turns ______ (a)in acids. Red litmus turns ______ (b) in alkalis.  red blue 8 Universal indicator changes to _____ (a)in acids & ______ (b) in alkalis with a series of colours in between. It is green in colour in _________ (c) substances. red blue neutral

  7. 9 The _________ (a) tells the degree of acidity & alkalinity of substances. The pH value ranges from_____ (b) to ____ (c) . > The pH value of _________ (d) substances is below 7. > The pH value of _________ (e) substances is 7. > The pH value of _________ (f) substances is above 7. pH scale 0 14 acidic neutral alkaline

  8. Importance of keeping the right pH 10.3 10 It is important for the different parts of our body to maintain their ________ (a) pH levels so that our body can function properly. For plants, the availability of nutrients depend on the acidity or alkalinity of the ______ (b) . proper soil 11 Many daily used products like cosmetics & personal care products show their ___________ (a) on their packs. pH values

  9. 10.4 The corrosive effect of acids 12 We can test for ______________ (a) by placing a burning splint at the mouth of the test-tube full of the gas. It gives out a ‘pop’ sound. hydrogen gas 13 Dilute acids react with some metals to give _____________ (a) . The acids are __________ (b) to these metals. hydrogen corrosive

  10. marble limestone 14 Dilute acids also react with building materials made of _______________ (a) to give _______________ (b) . That is why acids corrode our buildings & statues. calcium carbonate carbon dioxide sandstone

  11. 10.5 Acid rain ——the invisible threat 15 The average pH value of rainwater is about ______ (a) because _______________ (b) in theair can dissolve in it . The pH of acid rain is below ______ (c) 。 5.6 carbon dioxide 5.6

  12. 16 _________ (a) is formed when acidic gases like _________________ (b) & _______________ (c) dissolve in the rainwater. The acidic gases are given off from factories, power stations & vehicles. acid rain sulphur dioxide nitrogen oxides

  13. growth of plants p.59 17 The harmful effect of acid rain is slow but destructive. It_________ (a) our buildings & statues. It can also ___________ (b) in our rivers, lakes & the sea. It can affect the _______ __________ (c) by turning the soil acidic & toxic. corrodes destroy life 18 We can help reduce air pollution by using ________ (a) more efficiently. energy

  14. 10.6 Everyday uses of acids & alkalis 19 Acids can be used to _________ (a) food because it can stop the growth of micro-organisms. preserve 20 _________ (a)contains acetic acid and is commonly used for food preservation. Vinegar

  15. 21 Fruits like apple, banana, pear and peach turn brown when they are cut and left in the air for a period of time. Acids can prevent fruits from ___________(a)。 browning 22 Acids & alkalis are commonly used as ___________________ (a) . For example, hydrochloric acid is used in toilet cleansers, caustic soda in oven cleansers and ammonia solution as window cleansers. cleansing agents

  16. 23 Acids & alkalis _____________ (a) each other in a chemical reaction called ______________ (b) . In this reaction, _____ (c) & ______ (d) are formed. neutralize neutralization salt water

  17. 24 We can make use of neutralization to solve many daily problems. Examples are： > Use of ___________ (a) to treat stomach-ache > Use of acids or alkalis to treat wasp, bee, mosquito & ant stings > Neutralization of acidic & alkaline industrial wastes before _________ (b) antacid disposal

  18. 10.7 Safety matters related to the use of acids & alkalis 25 Acids & alkalis should be handled carefully because they are _______________ (a) . corrosive

  19. 26 ____________ (a) acid is a solution that contains a high proportion of acid in water._____________ (b) alkali is a solution that contains a high proportion of alkali in water. They are much more ___________ c) than dilute acids & alkalis. Concentrated Concentrated corrosive

  20. concentrated acid / alkali water 27 Concentrated acids and alkalis give out heat on __________ (a) . We must dilute concentrated acids & alkalis by adding them to water, but not by adding water to them. We must wear protective clothes, safety goggles & gloves when doing so. dilution

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