Acid, bases and salts

Question 1

what is a pH scale

Answer 1

measures acidity and alkalinity

Question 2

what can a base be

Answer 2

oxides or hydroxides of metals

Question 3

what can an alkali be

Answer 3

a soluble base

Question 4

how can pH be measured

Answer 4

pH meter: gives exact pH value
litmus, methyl orange, thymolphthalein- only tell you if acidic not how acidic
universal indicator- gives rough pH

Question 5

what colour does litmus paper in acid

Answer 5

red

Question 6

litmus paper in alkali

Answer 6

blue

Question 7

methyl orange in acid

Answer 7

red

Question 8

methyl orange in alkali

Answer 8

yellow

Question 9

methyl orange in neutral

Answer 9

orange

Question 10

thymolphthalein in acid

Answer 10

colourless

Question 11

thymolphthalein in alkali

Answer 11

blue

Question 12

thymolphthalein in neutral

Answer 12

colourless

Question 13

which acids are strong

Answer 13

HCL
H2SO4
NHO3

Question 14

which bases are strong

Answer 14

NaOH
KOH

Question 15

which acids are weak

Answer 15

CH3COOH (ethanoic)
H2CO3

Question 16

which bases are weak

Answer 16

NH3
metal carbonates

Question 17

what are oxides

Answer 17

compounds containing oxygen and another element

Question 18

what are the basic oxides

Answer 18

metal oxides and they react with acids. e.g. MgO

Question 19

what are the acidic oxides

Answer 19

non-metal oxides and react with bases. e.g CO2, SO2, P4O10

Question 20

what are the amphoteric oxides

Answer 20

Al2O3 and ZnO they react with both

Question 21

what are the neutral oxides

Answer 21

CO, N2O they do not react with either

Question 22

what is definition 1 of acids

Answer 22

acids are compounds that produce hydrogen ions, H+, when dissolved in water.
e.g. when hydrogen chloride gas (HCL) dissolves in water, it dissociates to make hydrogen ions and chloride ions

Question 23

what is definition 1 of alkalis

Answer 23

alkalis are compounds that produce hydroxide ions when they dissolve in water

Question 24

what is definition 2 of acids

Answer 24

are proton (H+) donors

Question 25

what is definition 2 of alkalis

Answer 25

proton (H+) acceptors

Question 26

how to compare weak and strong acids or alkalis using pH

Answer 26

strong acids have lower pH because there are more hydrogen ions in the solution . The higher the concentration of hydrogen ions, the lower the pH

Question 27

how to compare weak and strong acids or alkalis using conductivity

Answer 27

strong acids conduct better than weak acids because there are more ions in solution. Similarly, strong alkalis, acids show higher conductivity because there are more ions in solution and have higher pH because there are more hydroxide ions.

Question 28

which salts are soluble

Answer 28

all sodium, potassium and ammonium salts. All nitrates. Chlorides, bromides, iodides. Sulfates. Sodium, potassium and ammonium carbonates

Question 29

which salts are insoluble

Answer 29

silver and lead chloride. Calcium, barium and lead sulfate. All other carbonates are insoluble

Question 30

what is the method of producing salt+ hydrogen

Answer 30

1. Add metal to acid 2. metal dissolves as it reacts and effervescence is seen 3. add metal until no more dissolves 4. once effervescence stops and some metal is left. filter off the excess metal. 5. evaporate some of the water from the filtrate and let to cool down and crystallise

Question 31

what is the method of producing salt+ water + carbon dioxide

Answer 31

1. add metal carbonate to hot acid 2. carbonate dissolves and fizzes as it reacts 3. add carbonate until no more dissolves 4. once effervescence stops and some carbonate is left, filter off the excess carbonate 5. evaporate some water from the filtrate and let to cool down crystallize

Question 32

what is another method of producing salt+ water

Answer 32

1. Add metal oxide to acid 2. warm over bunsen burner to dissolve the base 3. Add metal oxide until no more dissolves 4. filter off excess metal oxide 5. evaporate some of the water from the filtrate and let to cool down and crystallise

Question 33

what is another method of preparing salt + water

Answer 33

titration 1. put the acid in a burette 2. pipette the alkali into a conical flask and add indicator 3. titrate until indicator changes colour and record the volume added 4. repeat the experiment without the indicator using the same volume 5. evaporate some of the water and let to cool down and crystallise

Question 34

what is a way of preparing an insoluble salt + soluble salt

Answer 34

1. Mix two soluble salts and stir 2. precipitate forms 3. filter the mixture- the insoluble salt is the residue 4. rinse the precipitate with water