acids alkalis bases

Question 1

what are acids

Answer 1

acid is a substance that produce hydrogen ions in aqueous solution

Question 2

why must water be present to be able to have acidic properties

Answer 2

water must be present then the hydrogen ions can be produced, its the hydrogen ions that gives the acid its acidic properties

Question 3

physical properties of acids

Answer 3

1. sour
2. turn blue litmus paper red
3. can conduct electricity because it dissolves in water to form solutions

Question 4

chemical properties of acids

Answer 4

1. acid + metal –> salt + hydrogen gas
2. acid + carbonate –> salt + water + carbon dioxide
3. acid + base –> salt + water

Question 5

how to test for hydrogen gas

Answer 5

test : insert a lighted splint into test gas
result : it will extinguish a “pop” sound

Question 6

how to test for carbon dioxide gas

Answer 6

test : bubble test gas through limewater
result : white precipitate will form in limewater

Question 7

do all metals react with acids? why?

Answer 7

no, some exceptions are copper, silver, gold, lead. lead when reacted with acid, it forms an insoluble layer around the lead (ll) chloride or lead (ll) sulfate that prevents further reaction.

Question 8

what are alkalis

Answer 8

alkalis are a soluble base that dissolves in water to form hydroxide ions

Question 9

are all alkalis bases

Answer 9

yes

Question 10

are all bases alkalis

Answer 10

no

Question 11

what are the two groups of alkalis

Answer 11

oxides and hydroxides

Question 12

physical properties of alkalis

Answer 12

1. soapy feeling, bitter taste
2. turn red litmus paper blue

Question 13

chemical properties of alkalis

Answer 13

1. alkalis + acid –> salt + water
2. alkalis + ammonia salt–> salt + water + ammonia gas (NH4)

Question 14

how to test for ammonia gas

Answer 14

test : use moist red litmus paper
result : red litmus paper blue

Question 15

what are bases

Answer 15

bases are metal oxides or hydroxides that reacts with acids to form salt and water only

Question 16

which number has the most hydrogen ions than hydroxide ions

Answer 16

1-4

Question 17

which number of the universal indicator is neutral

Answer 17

7

Question 18

why is it important to control the ph of soil

Answer 18

ph of soil affects the growth and development of plants, need to be more careful

plants grow best in neutral of slightly acidic

Question 19

what leads to an increase in ph of soil

Answer 19

too much fertilisers, acid rain

Question 20

how to control ph of soil

Answer 20

use liming, calcium hydroxide/calcium oxide

Question 21

types of oxides

Answer 21

1. acidic oxide
2. basic oxide
3. amphoteric oxide
4. neutral oxides

Question 22

what are acidic oxides

Answer 22

1. grp 14-17, gas at r.t.p, dissolves in water to form acid, reacts with alkali to form salt and water only

Question 23

example of acidic oxide

Answer 23

CO2, SO2, SO3

Question 24

what are basic oxides

Answer 24

metallic oxides grp 1 to 2, most are insoluble in water except for sodium oxide and potassium oxide.

Question 25

examples of acidic oxide

Answer 25

MgO, Na2O, K2O, CaO

Question 26

what are amphoteric oxides

Answer 26

behave like an acidic oxide, reacts with base to form salt and water only
behave like a basic oxide, reacts with acid to form salt and water

Question 27

examples of amphoteric oxides

Answer 27

ZnO, PbO, Al2O3

Question 28

what are netrual oxides

Answer 28

insoluble in water, does not show any acidic or alkali properties, monxides

Question 29

example of neutral oxide

Answer 29

H2O, NO, CO