Year 8 Acids, Alkalis, Neutralization and Reactivity of Metals Revision

1. True or False?

1. We can use indicators to test if solutions are acids or alkali -True
2. Litmus paper only tests for acids-False
3. the pH scale uses colour to show if solutions are acids or alkalis -True
4. strong acids are blue on the pH scale -False
5. strong alkalis are blue on the pH scale -True
6. water is a strong acid -False
7. a neutral solution would be red in colour -False
8. hydrochloric acid is an alkali -False
9. lemon juice is an acid -True
10. sodium hydroxide is an alkali -True

2.

3. Table 1 below shows the colour of universal indicator in acidic, neutral and alkaline solutions.

	acidic				neutral		alkaline
colour of indicator	red	orange	yellow	green		blue		dark blue	purple

table 1

3. Ramy tested different liquids with the indicator solution.
   His results are shown in table 2 below.

liquid	colour of indicator solution
Milk	green
lemonade	orange
water	green
fruit juice	red
washing-up liquid	blue

table 2

(a) Use Ramy’s results to answer the following questions.

(i) Give the name of one acidic liquid in table 2.

.................Lemonade............................................................................................

(ii) Give the name of one neutral liquid in table 2.

....................Water.........................................................................................

(b) Ramy dissolved some bicarbonate of soda in distilled water.
This produced an alkaline solution.

(i) Ramy added the indicator to the alkaline solution.

Suggest what colour the indicator became.

Use table 1 to help you.

..........................Dark Blue......................................

(ii) Ramy added lemon juice to the solution of bicarbonate of soda.

How could he tell that a gas was produced?

.......If there would be Bubbles popping out of the test tube or if it evaporated or dissolved

4. (a) Neutral litmus paper is:

purple in neutral solutions;
red in acids;
blue in alkalis.

Use this information to answer the questions.

(i) A piece of neutral litmus paper turned red in some grapefruit juice. What does this show about the grapefruit juice?

...........The grapefruit juice is an acid..................................................................................................

(ii) Gwen added drops of sodium hydroxide solution to the grapefruit juice. The litmus paper soon turned blue. What does the blue colour show about the sodium hydroxide solution?

........Sodium hydroxide is an alkali.....................................................................................................

(iii) Gwen then tested some water with a new piece of neutral litmus paper. The pH of the water was 7. What colour was the litmus paper in the water.

....Purple.........................................................................................................

3. Indigestion can be caused when too much hydrochloric acid is produced in the stomach.
   Magnesium carbonate can be used to treat indigestion.

Winston crushed some indigestion tablets containing magnesium carbonate. He added them to hydrochloric acid in a test-tube. The mixture fizzed.

The word equation for the reaction is shown below.

magnesium + hydrochloric  magnesium + carbon + water
carbonate acid chloride dioxide

(i) Use the word equation to explain why the mixture fizzed when the reaction took place.

It started to turn into a gas!

(ii) Winston continued to add crushed tablets to the acid until the mixture stopped fizzing.
Why did the fizzing stop?

It had been dissolved before and turned into a gas and then as he kept putting more it got filled and couldn't be turned into gas and got trapped with less amount of water.