7E End of Unit Test

7E End of Unit Test

Name ______Class ______

1Put a circle around the three things in this list that are acidic.

tap water sugar orange juice salt

vinegar flour lemonade mineral water

[3 marks]

ABCD

Which of these hazard warnings means that a chemical:

ais flammable ______

[1 mark]

bis poisonous ______

[1 mark]

cis corrosive ______

[1 mark]

dis an irritant?______

[1 mark]

eWhat does ÔflammableÕ mean? ______

______

[1 mark]

fWhich of the hazard symbols would you be most likely to find on a:

iconcentrated acid? ______

iidilute acid? ______

[2 marks]

3Sarah tested a number of substances with red cabbage juice to see if they were acids or alkalis. She tried lemonade, tap water, toothpaste, vinegar and washing powder. When she mixed the lemonade with the red cabbage juice it went red.

aName one other substance that would also make the cabbage juice go red.

______

[1 mark]

bName one substance in the list that is an alkali. ______

[1 mark]

cWhat name do we give to substances like red cabbage that can change colour when mixed with acids and alkalis?

______

[1 mark]

dName another substance that Sarah could have used instead of red cabbage that would also change colour.

______

[1 mark]

eWhat colour would this substance be in an acid? ______

[1 mark]

fWhat name do we give to substances that are neither acid nor alkali?

______

[1 mark]

gSarah had a pen which had purple ink in it. She wondered if the ink might work as an indicator. Explain how she could do a simple test to find out.

______

[2 marks]

4Asif wanted to find out whether the acid or the alkali was stronger.

He put 5cm3 of alkali in a tube. He added acid 1cm3 at a time. Each time he added acid, he measured the pH of the solution.

His results are in the table.

Volume of acid added (cm3) / pH
Start (no acid) / 10.5
Ê1 / 10.5
Ê2 / 10.0
Ê3 / Ê9.5
Ê4 / Ê7.5
Ê5 / Ê5.0
Ê6 / Ê4.0
Ê7 / Ê3.5
Ê8 / Ê3.5
Ê9 / Ê3.0
10 / Ê3.0

aSuggest a way in which Asif could have measured the pH of the solution.

______

[1 mark]

bPlot these results on the graph paper. Join up the points with a smooth line.

[3 marks]

cHow much acid did Asif need to make the solution neutral? Tick the correct answer.

[1 mark]

Exactly 4 cm3

Between 4 and 5 cm3

Exactly 5 cm3

More than 5 cm3

dWhich was stronger, the acid or the alkali? Explain your reasoning.

______

[2 marks]