acids 3.4

Question 1

ph less than 7

Answer 1

acid

Question 2

ph more than 7

Answer 2

alkali

Question 3

methyl orange

Answer 3

acid - red
neutral - yellow
alkali - yellow

Question 4

phenolphthalein

Answer 4

acid - colourless
neutral - colourless
alkali - pink

Question 5

red litmus paper

Answer 5

acid - red
neutral - red
alkali - blue

Question 6

blue litmus paper

Answer 6

acid - red
neutral -blue
alkali - blue

Question 7

% nitrogen in the air

Answer 7

78%

Question 8

% oxygen in air

Answer 8

21%

Question 9

% argon in air

Answer 9

0.96%

Question 10

% carbon dioxide in air

Answer 10

0.04%

Question 11

4 most abundant gases in the air

Answer 11

nitrogen
oxygen
argon
carbon dioxide

Question 12

how to measure the % of oxygen in the air

Answer 12

react it with a metal, the air will gradually decrease in volume until all of the oxygen has been added to the metal. Then calculate the decrease in volume of air and divide it by the initial vol

Question 13

what is element combustion

Answer 13

when an element reacts with oxygen to produce an oxide

Question 14

name and state of oxide - metal

Answer 14

metal oxide, solid

Question 15

name and state of oxide - non metal

Answer 15

non-metal dioxide, gas

Question 16

magnesium and oxygen combustion

Answer 16

2Mg + O2 -> 2MgO
bright white light and white powder formed

Question 17

sulphur and oxygen combustion

Answer 17

S + O2 -> SO2
blue flame

Question 18

hydrogen and oxygen combustion

Answer 18

2H2 + O2 -> 2H2O
squeaky pop

Question 19

test for oxygen

Answer 19

glowing splint relights

Question 20

what happens when you dissolve a metal oxide in water

Answer 20

alkaline solution

Question 21

what happens when you dissolve a non-metal dioxide in water

Answer 21

acidic solution

Question 22

how to determine whether an unknown element is metal or non-metal

Answer 22

-combust in oxygen
-dissolve the oxide formed
-check the pH of the solution with an indicator

Question 23

acid + base

Answer 23

salt + water

Question 24

observation in an acid + base reaction

Answer 24

base disappears, as it is used up in the reaction

Question 25

how to make salt crystals

Answer 25

-add excess base to a hot acid (makes the salt solution quickly and uses all of the acid up -filter out the excess base, collect the salt solution (filtrate) in an evaporating base -heat the salt solution until crystals form around the edge -evaporation of water allows crystals o form

Question 26

acid + carbonate

Answer 26

salt + water + carbon dioxide

Question 27

observations in an acid + carbonate reaction

Answer 27

-carbonate disappears, it is used up in the reaction -there is fizzing, because CO2 is produced

Question 28

test for carbon dioxide

Answer 28

limewater turn cloudy when CO2 is present

Question 29

what is an acid

Answer 29

H+ donor proton donor

Question 30

what is a base

Answer 30

proton acceptor

Question 31

what is an alkali

Answer 31

soluble base OH- donor