reactions of metals

Question 1

how can you determine the reactivity of metals?

Answer 1

the reactivity of metals is determined by how easily they lose electrons and form positive ions ( cations)

Question 2

what is the trend in the reactivity series ?

Answer 2

the reactivity series shows metals in order of decreasing reactivity.

Question 3

what do metals react with to lose electrons? relate to the reactivity series trend.

Answer 3

when metals react with water or acid they lose electrons forming positive ions (cations). The higher up a metal is in the reactivity series, the more easily it reacts with water or acid.

Question 4

what is produced when metals react with water?

Answer 4

Metal + Water = Metal Hydroxide + Hydrogen

Question 5

what are the most reactive metals?

Answer 5

1. potassium
2. Sodium
3. Lithium

Question 6

what are the least reactive metals?

Answer 6

1. Hydrogen
2. Copper
3. Gold

Question 7

what is produced when metals react with water?

Answer 7

Metal + Water = Metal Hydroxide + Hydrogen

Question 8

what is produced when metals react with dilute acids?

Answer 8

Acid + Metal = Salt + Hydrogen

Question 9

In an experiment investigating how metals react with hydrochloric acid, how can you calculate the speed of an acid with a metal?

Answer 9

the speed of reaction is indicated by the ate of which the bubbles f hydrogen are given off.

Question 10

Give another example of an experiment that you investigates the rate of reaction between metals and water/acids.

Answer 10

You can investigate the reactivity of metals by measuring the temperature change of the reaction with an acid or water over a set time period, the more reactive the metal, the greater the temperature change should be. the control variables that need to be kept the same are the mass and surface areas of metals each time. th

Question 11

what are the variables for the experiment investigating the reactivity of metals using water/acid.

Answer 11

the control variables that need to be kept the same are the mass and surface areas of metals each time. the independent variable that is changed is the different metal. the dependant that is measured is the reactivity of different metals

Question 12

what happens when metals react with oxygen?

Answer 12

They produce metal oxides

Question 13

what are the reactions of adding metals and oxygen called?

Answer 13

Oxidation as metal gains oxygen

Question 14

what are the reactions of metals losing oxygen called?

Answer 14

Reduction

Question 15

Explain displacement in reactions.

Answer 15

A more reactive
metal can displace a less reactive metal from its compounds. For example, magnesium is more reactive than copper. It displaces copper from copper sulphate
solution:
Magnesium + copper sulfate → magnesium sulfate + copper

Question 16

write two half equations for

Magnesium + copper sulfate → magnesium sulfate + copper

Answer 16

Mg(s) → Mg2+(aq) + 2e- (oxidation)

Cu2+(aq) + 2e- → Cu(s) (reduction)

Question 17

why don’t we use electrolysis for extracting compounds that are lees reactive than carbon? how is copper extracted from its ore?

Answer 17

electrolysis is expensive as it would use large amounts of electric energy instead if a metal is less reactive than carbon it can be extracted by heating it with carbon.
Molten. copper can be produced from copper oxide by heating with carbon:
Copper oxide + carbon → copper + carbon dioxide

2CuO(s) + C(s) → 2Cu(l) + CO2(g)

Copper oxide is reduced as carbon is oxidised, so this is an example of a redox reaction.

Question 18

how is iron extracted?

Answer 18

Iron(III) oxide is reduced to molten iron when it reacts with carbon. One of the products is carbon monoxide:

iron(III) oxide + carbon → iron + carbon monoxide

Question 19

How is aluminium extracted?
And why is it expensive?

Answer 19

aluminium is extracted using electrolysis this is because aluminium is more reactive than carbon.
it is expensive because lots of of the large amounts of electric energy used during the extraction process -electrolysis

Question 20

what is aluminium ore treated to produce?

Answer 20

aluminium oxide

Question 21

ionic compounds in electrolysis must be…

Answer 21

. Dissolved in water (if soluble)
.In the molten state (if it was insoluble to water) this is because when dissolved or molten the ions can move freely and conduct electricity

Question 22

how can we reduce the costs of aluminium extraction?

Answer 22

the melting point of aluminium oxide is too high, lots of energy is needed to break its ionic bonds which is very expensive. To reduce costs, powdered aluminium oxide is dissolved in molten cryolite. This ionic compound melts at a lower temperature than aluminium oxide, reducing costs. However, significant amounts of energy are required to melt the cryolite.,

Question 23

for the electrolysis process of extracting aluminium explain why both electrodes are made out of graphite.

Answer 23

graphite is a form of carbon with a high melting point it is used because it can conduct electricity as it has one delocalised electron and it also does not react with other substances easily.

Question 24

what electrons are attracted to the cathode and anode?

Answer 24

at the cathode(the negative electrode) the positive aluminium ions are attracted gaining electrons becoming atoms.
At the anode (positive electrons) oxide ions are attracted forming oxygen atoms

Question 25

why must the anodes be replaced?

Answer 25

as the oxygen produced reacts with the carbon anodes, forming carbon dioxide. so the anodes are gradually oxidised which ads to the cost of producing aluminium.