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UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS | Methodist High School Cambridge Checkpoint SCIENCE [Biology] | Page 1 of 5 WORKSHEET CHAPTER 10 :  

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Q.1 This

ACIDS AND ALKALI

Write in dark blue or black Name pen. : You may use a soft pencil for any diagrams, graphs or Roll rough working. No. Do not use highlighters, glue or correction fluid. Show all your working in the booklet. Marks The number of marks is : given in brackets [ ] at the end of each question or part question. Hydrochloric acid is used to clean a metal surface by removing the oxide layer on the metal. is because hydrochloric acid has a …..X….. pH and the metal oxide is …..Y….. What are X and Y?

Ans

Q.2

In the experiment shown, the dilute sulphuric acid is run into the flask of aqueous barium hydroxide until the reaction is complete.

Which processes occur in this reaction? Ans

Q.3

The diagram shows the pH values of the soil in X and Y, two parts of the garden of a house. The house owner wishes to use lime to neutralise the soil in one part of the garden. To which part should the lime be added, and why?

Ans

Q.4

Sulphuric acid is a strong acid, ethanoic acid is a weak acid. Explain the difference between a strong acid and a weak acid.

Ans. ………………………………………………………………………………………………………………… ……………………………………………… ………………………………………………………………………………………………………………… ………………………………………………

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS | Methodist High School Cambridge Checkpoint SCIENCE [Biology] | Page 2 of 5 Q.5

Q.5

(a)

Which compound in polluted air can damage stonework and kill trees? A carbon dioxide Ans B carbon monoxide C lead compounds D sulfur dioxide The pH of chemicals found around the home may be tested using pH paper. Some typical results are shown below.

Answer the following questions using the above information. (i) What is the pH of oven cleaner? ....................................................................................................................................... ................................. (ii) Which is the most acidic solution? ....................................................................................................................................... ................................. (iii) What would be the pH of a neutral solution?

....................................................................................................................................... ................................. (b) Vinegar was also tested using pH paper and found to have a pH of 4.1. What colour did the pH paper become? ....................................................................................................................................... ................................. (c) When a wasp stings someone its injects a liquid in the person's skin. An old fashioned remedy for wasp stings is to rub vinegar on them. (i) Suggest the pH of the liquid which wasps inject into the skin. ....................................................................................................................................... ................................. (ii) What name is given to the reaction which happens between this liquid and the vinegar? ....................................................................................................................................... ................................. (iii) Name the colourless, tasteless liquid that is produced in this reaction. ....................................................................................................................................... ................................. Q.5 (a)

Nettles, bees and ants sting by injecting acid into your skin. Wasp stings are alkaline. How could you test to prove that the liquid from an ant is acid? ....................................................................................................................................... .................................

(b)

Vinegar is used to treat a wasp sting and ammonia to treat a bee sting. Explain why this works and what it tells you about vinegar and ammonia. ....................................................................................................................................... ................................. ....................................................................................................................................... .................................

(c)

Car batteries contain strong sulphuric acid.

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS | Methodist High School Cambridge Checkpoint SCIENCE [Biology] | Page 3 of 5 To treat a spillage from a car battery, you must first add lots of water then put washing soda on it. Explain this treatment. ....................................................................................................................................... ................................. ....................................................................................................................................... ................................. ....................................................................................................................................... .................................

ANSWERS Q.1

Ans Q.2

Hydrochloric acid is used to clean a metal surface by removing the oxide layer on the metal. This is because hydrochloric acid has a …..X….. pH and the metal oxide is …..Y….. What are X and Y? D: low basic In the experiment shown, the dilute sulphuric acid is run into the flask of aqueous barium hydroxide until the reaction is complete.

Which processes occur in this reaction? A Ans

Q.3

The diagram shows the pH values of the soil in X and Y, two parts of the garden of a house.

The house owner wishes to use lime to neutralise the soil in one part of the garden. To which part should the lime be added, and why? D

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS | Methodist High School Cambridge Checkpoint SCIENCE [Biology] | Page 4 of 5 D

Q.4 Ans.

Ans

Sulphuric acid is a strong acid, ethanoic acid is a weak acid. Explain the difference between a strong acid and a weak acid. sulphuric acid is completely ionised or few molecules and many ions ethanoic acid is partially ionised or many molecules and few ions

Q.5

Which compound in polluted air can damage stonework and kill trees? A carbon dioxide Ans B carbon monoxide D sulfur C lead compounds dioxide D sulfur dioxide

Q.5

The pH of chemicals found around the home may be tested using pH paper. Some typical results are shown below.

(a)

Answer the following questions using the above information. (i) What is the pH of oven cleaner? 12 (ii) Which is the most acidic solution? lemon juice (iii) What would be the pH of a neutral solution? 7 (b) Vinegar was also tested using pH paper and found to have a pH of 4.1. What colour did the pH paper become? red or orange (c) When a wasp stings someone its injects a liquid in the person's skin. An old fashioned remedy for wasp stings is to rub vinegar on them. (iv) Suggest the pH of the liquid which wasps inject into the skin. accept any pH greater than 7 up to 14 (v) What name is given to the reaction which happens between this liquid and the vinegar? neutralisation (vi) Name the colourless, tasteless liquid that is produced in this reaction. water Q.5 (a) (b) (c)

(a)

Nettles, bees and ants sting by injecting acid into your skin. Wasp stings are alkaline. How could you test to prove that the liquid from an ant is acid? add universal indicator/litmus red ⇒ acid Vinegar is used to treat a wasp sting and ammonia to treat a bee sting. Explain why this works and what it tells you about vinegar and ammonia. vinegar is acid , ammonia is alkaline , they neutralise the stings Car batteries contain strong sulphuric acid. To treat a spillage from a car battery, you must first add lots of water then put washing soda on it. Explain this treatment. water dilutes acid , washing soda neutralises it

UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONS | Methodist High School Cambridge Checkpoint SCIENCE [Biology] | Page 5 of 5 (b) vinegar is acid 1 ammonia is alkaline 1 they neutralise the stings 1 (c)