Acids

Question 1

give two reasons why hydrochloric acid is produced in the stomach

Answer 1

1) to help kill bacteria in our food
2) to help digestion, as some of the enzymes that break down food in to simpler substances only work in acidic conditions

Question 2

what are indigestion remedies

Answer 2

they are substances that contain antacids which neutralise excess stomach acid.

Question 3

give 3 compounds which can be used to neutralise acids to produce salts

Answer 3

metal oxides, metal hydroxides, metal carbonates

Question 4

give 3 general word equations of neutralisation

Answer 4

1) acid + metal oxide > salt + water
2) acid + metal hydroxide > salt + water
3) acid + metal carbonate > salt + water + carbon dioxide

Question 5

what type of salt do these acids produce:

1) hydrochloric acid
2) nitric acid
3) sulfuric acid

Answer 5

1) hydrochloric acid produces chloride salts
2) nitric acid produces nitrate salts
3) sulfuric acid produces sulfate salts

Question 6

what is electrolysis

Answer 6

a process in which electrical energy, from a d.c. supply, decomposes compounds

Question 7

which products are given off when dilute hydrochloric acid is electrolysed

Answer 7

hydrogen gas is produced at one electrode, and chlorine gas is produced at the other.

Question 8

Describe the chemical test for hydrogen

Answer 8

hold lighted splint in the mouth of a test tube. if the gas is hydrogen it will explode with a squeaky pop.

Question 9

Describe the chemical test for chlorine

Answer 9

hold a piece of damp blue litmus paper in the mouth of the test tube. if the gas is chlorine the paper will turn red and then turn white

Question 10

what gas can be obtained from the electrolysis of sea water

Answer 10

chlorine gas as sea water contains a lot of dissolved sodium chloride.

Question 11

what can chlorine be used to make

Answer 11

bleach and to make plastics such as poly(chloroethene), also called PVC

Question 12

what are the dangers of chlorine

Answer 12

it is a toxic gas, this makes it useful because it kills micro-organisms. it is also hazardous. chlorine is also very useful in industry, and millions of tonnes are produced every year. accidental leaks of chlorine from factories or fro tankers could harm or kill many people

Question 13

what does the electrolysis of water produce

Answer 13

it produces hydrogen and oxygen

Question 14

Describe the chemical test for oxygen

Answer 14

hold a glowing splint in the mouth of the test tube. if the gas is oxygen the splint will relight again.