C5 chemical changes

Question 1

oxidation

Answer 1

when oxygen is added to a substance/ or when a substance has lost electrons

Question 2

reduction

Answer 2

a reaction in which oxygen is lost or electrons are gained

Question 3

acids

Answer 3

substances that form H+ ions when they dissolve in water

Question 4

alkalis

Answer 4

form OH- when they dissolve in water
type of base

Question 5

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Answer 5

potassium
sodium
calcium
magnesium
aluminium
carbon
zinc
iron
tin
lead
hydrogen
copper
silver
gold

Question 6

spectator ions

Answer 6

ions unchanged in the reaction

Question 7

potassium reaction with water

Answer 7

quick reaction
hydrogen ignites quickly
metal sets alight, sparking and burns with lilac flame

Question 8

sodium with water

Answer 8

fizzes rapidly
melts to form ball
moves rapidly on water surface

Question 9

lithium

Answer 9

fizzes steadily
floats
shrinks until it disappears

Question 10

metals that react with dilute acid not water

Answer 10

aluminium
zinc
iron
lead

Question 11

metals that don’t react with dilute acids

Answer 11

copper
silver
gold
platinum

Question 12

carbon for extraction

Answer 12

only works if metal is less reactive than carbon
cheap and abundant

Question 13

acid + metal

Answer 13

–> hydrogen + salt

Question 14

redox reaction

Answer 14

one reaction gains electrons ( oxidation ) one loses electrons. ( reduction)

Question 15

acid + carbonate

Answer 15

–> salt + water + carbon dioxide

Question 16

acid + metal oxide

Answer 16

–> salt + water

Question 17

acid + hydroxide

Answer 17

–> salt + water

Question 18

weak acids

Answer 18

only partially ionise in water
not all of the acid molecules break up to form H+ ions
eg. ethanoic acid

Question 19

strong acid

Answer 19

fully ionise in water
all acid molecules broken up to form H+ ions
eg. hydrochloric acid, sulfuric and nitric acid