Acids, bases and indicators

Question 1

Define an acid

Answer 1

1. Dissolves in water to form hydrogen ions as the only positive ions.
2. Sour taste
3. Reacts with a base to form salt and water only

Question 2

Define a base

Answer 2

1. dissolve sin water to form hydroxide ions as the only negative ions.(solutions have a soapy feel)
2. Bitter taste
3. Neutralize acids to form salt and water only.

Question 3

Bases that are soluble in water are known as

Answer 3

Alkalis

Question 4

What is indicator?

Answer 4

A substance that shows one definite color in basic solution and a different definite color in acidic solution.

Question 5

State 2 types of indicators

Answer 5

1. simple acid-base indicators extracted from flower petals by crushing them, dissolving in acetone and filtering the mixture.
2. Commercial indicators

Question 6

procedure for making a simple acid-base indicator

Answer 6

1. crush petals in a mortar using a pestle.
2. add a solvent(propanone or ethanol)
3. decant to obtain the indicator

Question 7

Do commercial indicators show the strength of acids and bases?

Answer 7

No, they show the same color for all acids and the same color for all bases

Question 8

What are neutral substances?

Answer 8

neither basic nor acidic

Question 9

What is universal indicator

Answer 9

type of commercial indicator that shows a range of colors depending on the strength of the acid or base

Question 10

Universal indicator and strong acids show what color?

Answer 10

bright red

Question 11

Universal indicator and alkalis/bases show what color?

Answer 11

purple/violet

Question 12

0-3 on the pH chart indicates

Answer 12

strong acids

Question 13

4-6 on the pH chart indicates

Answer 13

weak acids

Question 14

7 on the pH chart indicates

Answer 14

neutral

Question 15

8-10 on the pH chart indicates

Answer 15

weak alkali

Question 16

11-14 on the pH chart indicates

Answer 16

strong alkali

Question 17

Name 3 commercial indicators

Answer 17

Phenolphthalein
litmus paper
methyl orange

Question 18

What is a pH scale?

Answer 18

a chart showing the degree of acidity or alkalinity

Question 19

3 Physical properties of acids

Answer 19

1. sour taste
2. very corrosive
3. Turn blue litmus red
4. pH value lower than 7

Question 20

3 Physical properties of bases

Answer 20

1. bitter taste
2. mild corrosion
3. turn red litmus blue
4. pH value higher than 7

Question 21

Acids react with metals to produce

Answer 21

salt and hydrogen gas

Question 22

lead reacts slowly with both _____ and_____. reaction stops after a short while due to formation of______

Answer 22

dilute sulphuric acid, hydrochloric acid, insoluble salt coatings

Question 23

Acids react with bases to give

Answer 23

salt and water only

Question 24

acids react with metal carbonates and hydrogen carbonates to give

Answer 24

a salt, carbon(iv)oxide and water