topic 3 chemical changes

Question 1

what ions do acids form

Answer 1

H+ ions

Question 2

what is a base

Answer 2

a substance that reacts with an acid to produce a salt and water

Question 3

what ions do alkalis form

Answer 3

OH- ions

Question 4

what colour is litmus in different pHs

Answer 4

red in acidic, purple in neutral, blue in alkaline

Question 5

what colour is methyl orange in different pHs

Answer 5

red in acidic and yellow in nuetral and alkaline solutions

Question 6

what colour is phenolphthalein in different pHs

Answer 6

colourless in acidic or neutral, pink in alkaline

Question 7

what is a neutralisation reaction

Answer 7

a reaction between a base and an acid

Question 8

what is produced in a reaction between an acid and a metal oxide

Answer 8

salt and water

Question 9

what is produced in the reaction between acid and metal hydroxide

Answer 9

salt and water

Question 10

what is produced in a rection between an acid and a metal

Answer 10

salt and hydrogen

Question 11

what is produced in the reaction between an acid and a metal carbonate

Answer 11

salt, water and carbon dioxide

Question 12

what is produced in the reaction between an acid and a metal carbonate

Answer 12

salt, water and carbon dioxide

Question 13

is common salts of sodium, potassium and ammonium soluble or insoluble

Answer 13

soluble

Question 14

are nitrates soluble or insoluble

Answer 14

soluble

Question 15

are common chlorides soluble or insoluble

Answer 15

soluble, except silver chloride and lead chloride

Question 16

are common sulfates soluble or insoluble

Answer 16

soluble except lead, barium and calcium sulfate

Question 17

are common carbonates and hydroxides soluble or insoluble

Answer 17

insoluble, except for sodium, potassium and ammonium ones

Question 18

how do you make a pure, dry sample of an insoluble salt

Answer 18

pick two soluble salts and mix them together

Question 19

how do you make a soluble salt

Answer 19

by reacting an acid that contains one of the ions that you want in the salt with an insoluble bas that contains the other ion you need

Question 20

what is electrolysis

Answer 20

the breaking down of a substance using electricity, an electric current is passed through an electrolyte causing it to decompose

Question 21

what is an electrolyte

Answer 21

a molten or dissolved ionic compound

Question 22

what is an electrochemical cell

Answer 22

a circuit, made up of the anode, cathode, electrolyte, a power source and the wires that connect the two electrodes

Question 23

how do you set up an electrochemical cell if your electrolyte is a solution

Answer 23

clean the surfaces of to inert electrodes using emery paper, place into a beaker filled with the electrolyte, connect the electrodes to a power supply

Question 24

how do you set up an electrochemical cell if your electrolyte is a molten ionic substance

Answer 24

put the solid in a crucible and heat until molten in a fume cupboard, dip two clean inert electrodes into the electrolyte and connect to a power supply

Question 25

at which electrode does oxidation happen in electrolysis

Answer 25

the anode