Acids Bases And Salts

Question 1

Why do crystals form on cooling hot saturated solution

Answer 1

When solution is hot, solubility is higher as it cools solubility decreases and crystals start to form

Question 2

Why is all the water not simply evaporated off the solution

Answer 2

Many salts , contain water of crystallisation so water is locked into the crystal structure of the salt during crystallisation

Question 3

Metal + acid -> metal salt + hydrogen
General observations

Answer 3

Fizzing
Metal disappears
Heat given out
Colourless solution formed

Question 4

Test for hydrogen

Answer 4

Lit splint gives sqeuky pop, the hydrogen is burning in the air to produce water

2H2 + O2 -> 2H2O

Question 5

Metal carbonate/hydrogen carbonate+ acid -> carbon dioxide + water + metal salt
Observations

Answer 5

Fizzing
Solid disappears (give colour)
Heat given out (bar sodium hydrogen carbonate)
Colourless (blue if copper salt) solution formed

Question 6

test for carbon dioxide

Answer 6

Bubble through lime water ( calcium hydroxide solution)
Colourless to milky

Question 7

Alkali/base + acid -> salt + water
Observations, what’s is also an alkali

Answer 7

Ammonia solution

Heat given out ( bar copper oxide )
If solid : some (colour) solid disappears
Colourless ( blue if copper salt solution formed )

Question 8

1 what observation if gas is produced
2 what observation if one reactant is a solid
3 what observation if insoluble
4 what are the exception to heat given out
5 what is soluble

Answer 8

1 Bubbles
2 (colour) soli disappears, (colour) solution is produced
3 metal disappears
4 copper(II) oxide , sodium hydrogen-carbonate
5 liquids

Question 9

Give colour
1acids at start
2 copper oxide
3 copper carbonate
4 solutions of copper salts
5 oxides and other compounds of group 1,2 and aluminium
6 solutions of group 1, 2 and aluminium compounds

Answer 9

1 colourless
2 black
3 green
4 blue
5 white
6 colourless

Question 10

Exothermic

Answer 10

Gives out heat to surroundings

Question 11

Endothermic

Answer 11

Reaction takes in heat from surroundings

Question 12

Corrosive
Risk and precaution

Answer 12

May cause burns to skin
Damage eyes
Corrode metals

Wear gloves and safety glasses

Question 13

Acutely toxic
Risks and precautions

Answer 13

If ingested could belief threatening

Wear gloves and safety goggles
Use fume cupboard

Question 14

Flammable
Risk and precaution

Answer 14

Goes on fire easily when exposed to spark

Keep away from naked flame

Question 15

Explosive
Risks and precautions

Answer 15

Can explode easily form fire/ heat struck

Keep away from explosive sources

Question 16

Moderate hazard
Risk and precautions

Answer 16

May irritate skin

Wear safety goggle and gloves

Question 17

How can you tell if all the acid has been neutralised

Answer 17

When some solid remains at the bottom, Un reacted
If carbonate (or metal) is used there will be no more bubbles of gas

Question 18

Why is excess solid added

Answer 18

To make sure that all the acid has been neutralised
It leaves a pure solution of salt after filtration

Question 19

3 drying methods

Answer 19

Place in desiccator
Low temperature oven
Between 2 sheets of filter paper

Question 20

Spell indicator that goes form pink in alkali to colourless in solution

Answer 20

Phenolphthalein

Question 21

How to prepare pipette

Answer 21

Rinse with deionised water
Using pipette filler rinse with solution
Fill with solution
Hold the pipette vertically with the volume line at eye level
Run out the solution until the bottom of meniscus is on the line

Question 22

How to prepare burette

Answer 22

Rinse with deionised water
Rinse with solution
Fill with solution
Allow the solution to run out until the bottom of the meniscus is at the 0 line
Ensure the tip is full and there are no air bubbles

Question 23

Concentration (mol/dm3)

Answer 23

Th number of moles of a solid dissolved in 1dcm3 of solution

Question 24

Salt

Answer 24

Compound formed hen some or all hydrogen ions in an acid are replaced by metal ions or ammonium ions

Question 25

Strong acid/alkali

Answer 25

Ionise completely in solution

Question 26

Weak acid/alkali

Answer 26

Ionise partially in solution

Question 27

Phenolphthalein solution
1 acid
2 neutral
3 alkail

Answer 27

1 colourless
2 colourless
3 pink

Question 28

Methyl orange solution
1 acid
2 neutral
3 alkali

Answer 28

1 red
2 orange
3 yellow

Question 29

Blue litmus
1 acid
2 neutral
3 alkali

Answer 29

1 red
2 blue
3 blue

Question 30

Red litmus
1acid
2nuetral
3alkali

Answer 30

1 red
2 red
3 blue