Chemical changes

Question 1

whats formed when metals react with oxygen?

Answer 1

metal oxides, oxidation reaction

Question 2

what are the metals put in order of?

Answer 2

their reaction with water and dilute acid

Question 3

what are metals less reactive than carbon extracted from?

Answer 3

extracted from their oxides by reduction with carbon

Question 4

what is oxidation?

Answer 4

loss of electrons

Question 5

whats reduction?

Answer 5

gain of electrons

Question 6

what do acids react with some metals to produce?

Answer 6

salts and hydrogen

Question 7

what are acids neutralised by to produce salts and water?

Answer 7

alkalis and bases

Question 8

what does the salt produced in any reaction between acids and a base or alkali depend on?

Answer 8

the acid used
the positive ions in the base,alkali or carbonate

Question 9

what can soluble salts be made from?

Answer 9

acids reacting them with solid insoluble substances, solid is added to acid until no more reacts.

Question 10

what do acids produce in aqueous solutions?

Answer 10

hydrogen ions

Question 11

in neutralisation rections between an acid and an alkali what is formed?

Answer 11

hydrogen ions react with hydroxide ions to produce water

Question 12

whats completely ionised in an aqueous solution?

Answer 12

strong acids

Question 13

what is partially ionised in aqueous solutions?

Answer 13

weak acids

Question 14

what happens when the ph decreases by one unit?

Answer 14

hydrogen concentration of solution increases by a factor of 10

Question 15

what are electrolytes?

Answer 15

liquids and solutions that are able to conduct electricity.

Question 16

what does passing an electric current through electrolytes cause?

Answer 16

ions to move to the electrodes, positive ions to negative electrode (Cathode) and negatively charged ions move to the positive electrode (anode). this is electrolysis

Question 17

when is electrolysis used?

Answer 17

when the metal is too reactive to be extracted by reduction with carbon or if the metal reacts with carbon.

Question 18

why must the positive electrode (anode) by replaced?

Answer 18

its made of carbon which reacts with oxygen to produce carbon dioxide.

Question 19

whats produced at the negative electrode (cathode) if metal is more reactive than hydrogen?

Answer 19

hydrogen

Question 20

what is made at the positive electrode (cathode)?

Answer 20

oxygen unless the solution contains halide ions when the halogen is produced.

Question 21

whats formed at the cathode during electrolysis?

Answer 21

positively charged ions gain electrons so the reactions are reductions.