Level 5 Chemistry Questions 1. Burning fossil fuels causes air pollution. (a) Give the names of two fossil fuels.... and... Some fossil fuels contain sulphur. Complete the word equation for the reaction between sulphur and oxygen in the air. sulphur + oxygen... (b) Burning fossil fuels leads to the formation of acid rain. Acid rain has collected in this lake. A helicopter is dropping calcium hydroxide into the lake. Calcium hydroxide dissolves in water to form an alkaline solution. What effect does an alkali have on the ph of an acidic lake? Moulsham High School 1
When calcium hydroxide reacts with sulphuric acid in the lake a calcium salt is formed. What is the name of this salt? Tick the correct box. calcium carbonate calcium chloride calcium nitrate calcium sulphate (c) The photograph below shows trees damaged by acid rain. The trees have lost their leaves and have died. Explain why leaves are needed for a tree to grow. What effect does acid rain have on buildings made from limestone? maximum 6 marks Moulsham High School 2
2. Molly used a ph sensor to test different liquids. She dipped the probe of the sensor into each liquid and recorded the ph value in a table. (a) In the table below, tick one box for each liquid to show whether it is acidic, neutral or alkaline. One has been done for you. liquid ph value acidic neutral alkaline alcohol 7 dilute hydrochloric acid 2 distilled water 7 vinegar 3 sodium hydroxide solution 11 2 marks (b) Between each test Molly dipped the probe into distilled water. Why did she do this? Which other liquid in the table could Molly use between tests to have the same effect as distilled water? Moulsham High School 3
(c) Molly put a piece of magnesium into a test-tube containing 20 cm 3 of vinegar. She put another piece of magnesium into a test-tube containing 20 cm 3 of dilute hydrochloric acid. Molly thought that magnesium would react more vigorously with hydrochloric acid than with vinegar. What information in the table made Molly think this? How would Molly be able to tell if a more vigorous reaction took place with hydrochloric acid than with vinegar? (d) Complete the word equation for the reaction between magnesium and hydrochloric acid. magnesium + hydrochloric... +... acid 2 marks After some time this reaction stopped. Why did the reaction stop? maximum 9 marks Moulsham High School 4
3. Two groups of pupils investigated the factors affecting the time taken for an indigestion tablet to dissolve in 100 cm 3 of water. Group 1 recorded their results in the table below. results of group 1 tablet time taken to dissolve (s) whole tablet 34 broken tablet 28 finely crushed tablet 22 (a) What factor did group 1 change as they carried out their investigation?... (b) Before the investigation, group 1 made a prediction. They found this prediction was supported by the results in the table. What prediction did group 1 make?...... Moulsham High School 5
(c) Group 2 investigated how the temperature of the water affects the time taken for a whole tablet to dissolve. Here are their results. results of group 2 temperature of water (ºC) time taken to dissolve (s) 65 24 40 35 15 90 5 100 What factor did group 2 change as they carried out their investigation?...... (d) What pattern do the results recorded by group 2 show?...... (e) Look at the results presented by group 1 and group 2. Both groups used the same type of tablet. Estimate the temperature of water used by group 1.... C maximum 5 marks Moulsham High School 6
4. (a) Samantha opened a tin of white paint. The paint consisted of a liquid and particles of titanium dioxide that are insoluble in the liquid. The paint had separated into two layers, as shown below. liquid particles of insoluble titanium dioxide What type of substance is the paint? Tick the correct box. a compound an element a mixture What type of substance is titanium dioxide? Tick the correct box. a compound an element a mixture (iii) Why did the particles of insoluble titanium dioxide sink to the bottom? Moulsham High School 7
(b) Samantha stirred the paint and used it to paint a window frame. She got some of the paint on the glass. Samantha could not get the paint off the glass with water. When she used a different liquid called white spirit the paint came off. Why could she remove the paint with white spirit but not with water?...... maximum 4 marks Moulsham High School 8
5. (a) George used the apparatus below to find out what substances are produced when methanol burns. As the methanol burned, two different gases were produced. One of these gases condensed in the U-tube to give a colourless liquid. Give the name of this liquid.... The other gas turned the lime water cloudy. Give the name of this gas.... (b) Methanol is sometimes used in antifreeze. It can be added to water in car windscreen wash-bottles to prevent the water from freezing in cold conditions. Moulsham High School 9
The label on the bottle of antifreeze has two hazard warning symbols. What two precautions would you need to take when using this antifreeze? 1.... 2.... Water freezes at 0 C. The label on the bottle shows how the freezing point changes when different amounts of antifreeze are added to water. Terry put a mixture containing 10% antifreeze into the wash-bottle of his car. During the night the temperature dropped to 14 C. The wash-bottle burst. Explain why the wash-bottle burst. 2 marks Maximum 5 marks 6. Linda had a piece of red sandstone. She hammered it into pieces and then ground them into a powder using a pestle and mortar. Moulsham High School 10
She put the powder into a measuring cylinder with water and shook the mixture. The contents settled. (a) Linda said her results showed that sandstone is a mixture of two substances. How could she tell, from the results, that sandstone is a mixture of substances?...... (b) Linda then poured the cloudy water from the measuring cylinder through filter paper in a filter funnel. She said there might be salts dissolved in the colourless, clear liquid that came through the filter. What could Linda do to find out if there were salts dissolved in the colourless, clear liquid? Moulsham High School 11
What would she see if there had been salts dissolved in the colourless, clear liquid? (c) Sandstone is a sedimentary rock. Four stages in the formation of sedimentary rock are listed below. They are not in the correct order. compacted deposited weathered transported Put these stages in the correct order. One has been done for you. stage 1...weathered... stage 2... stage 3... stage 4... Maximum 4 marks Moulsham High School 12