Chemical Changes

Question 1

pH 0-5 is?

Answer 1

ACID

Question 2

pH 9-14 is?

Answer 2

ALKALIS

Question 3

what are the different ways you can work out pH of a solution?

Answer 3

• universal indicator

- pH probe ( more accurate that indicator as it gives a numerical value)

Question 4

acid + base

Answer 4

—–> salt + water

Question 5

what ions do acids form in water ?

Answer 5

H+

Question 6

neutralisation between acids and alkali?

Answer 6

H+ + OH- ——> H20

Question 7

what is a base ?

Answer 7

any substance that will react with an acid to form a salt

Question 8

what is titration used for ?

Answer 8

used to find concentration

Question 9

what is the difference between strong and weak acids when reacting with water ?

Answer 9

strong acids FULLY IONISE

weak acids DO NOT fully ionise

Question 10

what does acid strength tell you?

Answer 10

what proportion of the acid molecules ionise in water

Question 11

what does the acid concentration tell you?

Answer 11

measures how much acid there is in a certain volume of water

the larger the amount of acid there is in a certain volume the more concentrated the acid is

Question 12

ACID + METAL OXIDE

Answer 12

= SALT + WATER

Question 13

ACID + METAL HYDROXIDE

Answer 13

= SALT + WATER

Question 14

increasing acid concentration will do what to the pH?

Answer 14

DECREASE pH

Question 15

TRUE or FALSE

you can have a concentrated but weak acid and a dilute but strong acid?

Answer 15

TRUE

Question 16

ACID + METAL CARBONATE

Answer 16

= SALT + WATER + CARBON DIOXIDE

Question 17

ACID + METAL

Answer 17

= SALT + HYDROGEN

Question 18

what is the speed of the reaction indicated by?

Answer 18

the rate at which bubbles of hydrogen are given of

Question 19

METAL + WATER

Answer 19

= METAL HYDROXIDE + HYDROGEN

Question 20

how are most metals found?

Answer 20

as a compound with oxygen- ORES

Question 21

OIL RIG

Answer 21

Oxidation Is Loss
Reduction Is Gain

of electrons

Question 22

Metals and acids make what type of reaction?

Answer 22

REDOX

Question 23

what is electrolysis?

Answer 23

to split up with electricity

Question 24

what does the electrolyte have to be for electrolysis to take place?

Answer 24

MOLTEN or DISSOLVED

Question 25

what happens to ions during electrolysis?

Answer 25

ions move towards the electrodes where they react and then the compound decomposes

Question 26

what charge in the anode ?and what ions does it attract?

Answer 26

ANODE= positive electrode
attracts NEGATIVE ions
- they will loose electrons OXIDISED

Question 27

what charge is the cathode? and what ions does it attract?

Answer 27

CATHODE= negative electrode
attracts POSITIVE ions
- they will gain electrons REDUCED

Question 28

why does the ionic compound have to be molten or dissolved?

Answer 28

because it requires free moving ions

Question 29

what are the molten ionic compounds broken up into?

Answer 29

they are broken up into their elements

Question 30

what is negative about electrolysis?

Answer 30

• very expensive

- requires a lot of energy

Question 31

what is the half equation for oxygen?

Answer 31

2O2- ——> O2 + 4e-

Question 32

what is present in aqueous solutions?

Answer 32

hydrogen ions H+

hydroxide ions OH-

Question 33

what displaces the OH- ions?

Answer 33

HALIDE IONS

Cl- , Br- , I-

Question 34

METAL + ACID

Answer 34

= SALT + HYDROGEN

Question 35

METAL CARBONATE + ACID

Answer 35

= SALT + WATER + CARBON DIOXIDE