Topic 3

Question 1

Give the meaning of this symbol:

Answer 1

Toxic

Question 2

Which has a pH greater than 7 - Acid or Alkali?

Answer 2

Alkali
Acids are from 1-6
Neutral is 7
Alkali’s are from 8-14

Question 3

Name the acid produced by the stomach.

Answer 3

Hydrochloric Acid

Question 4

How can we test how indigestion tablets work.

Answer in as much detail as possible.

Answer 4

1) Crush up one dose of indigestion tablet(s) and dissolve it in water in a conical flask. to make sure it is a fair test, you should always use the same volume of water (e.g. 25cm3) and heck that the tablet had completely dissolved.
2) Add three drops of indicator to the conical flask. This will change colour when the solution has been neutralised.
3) Fill a burette, (a tall, thin measuring tube that has a tap on the bottom) with hydrochloric acid. Make sure you fill it carefully so you know how much acid you’ve got to begin with.
4) Using the burette, add the acid to the conical flask a bit at a time, giving the conical flask a regular swirl.
5) The end-point is when the colour change lasts rather then disappearing after a few seconds. When you think it’s about to be reached, go especially slow-drip by drip.
6) When the indicator changes colour, the alkali has been neutralised and you should stop adding acid.
7) Read the Burette to work out what volume of acid you’ve added to the alkali.
8) Repeat the experiment three times for each type of tablet and take an average of the volume of acid needed. this will increase the reliability of your results.

The most effective tablet is the one which requires the most acid to neutralise it - because it will be able to neutralise the largest ampunt of acid in the stomach.

Question 5

What do you get when you react an acid with a metal oxide?

Answer 5

Acid + Metal Oxide -> Salt + Water

Acid + Metal Hydroxide -> Salt + Water

Question 6

Write a simple equation for the reaction of hydrochloric acid with sodium carbonate.

Answer 6

2HCl+Na2CO3->2NaCl+H2O+CO2

Question 7

Is the anode positive or negative?

Answer 7

The anode is the positive terminal

Question 8

Are anions or cations attracted to the anode?

Answer 8

Anions are attracted to the anode

Question 9

How would you test for hydrogen gas?

Answer 9

Put a lit splint into a what may seem empty test tube, if there is hydrogen around, the splint will burn with a squeaky pop

Question 10

Name a product of the electrolysis of salt

Answer 10

Chlorine gas

Question 11

When water undergoes electrolysis, what gases are given off?

Answer 11

Hydrogen and oxygen