Chemical reactions

Question 1

What does metal + oxygen make

Answer 1

A metal oxide

Question 2

Oxidation in terms of oxygen?

Answer 2

Element/ compound that has been oxidised = gained oxygen

Question 3

Reduction in terms of oxygen?

Answer 3

Element/ compound that has been reduced = lost oxygen?

Question 4

How to test a metal’s reactivity?

Answer 4

React with water at room temperature:
Potassium + sodium + lithium = react very rapid
Calcium = fairly rapid reaction
Lower metals don’t react

Question 5

How to test a less reactive metal’s reactivity?

Answer 5

React with dilute acid at room temp
Potassium + sodium + lithium = dangerously explosive
Calcium = extremely rapid
Magnesium = rapid
Zinc = fairly rapid
Iron = slow
Copper = doesn’t react

Question 6

What determines a metal’s reactivity?

Answer 6

Their ability to lose electrons and form positive ions

Question 7

How does the reactivity change in group 1 metals?

Answer 7

As you go down the group = more reactive
Further down = more shells
More shells means less electrostatic attraction between nucleus and the reacting electron
Therefore it’s easier for the electron to react

Question 8

How to extract metal from metal oxides?

Answer 8

Using displacement reactions

Question 9

Why do we use carbon to extract metals?

Answer 9

It’s cheap
If the metal is less reactive than carbon eg zinc, iron and copper

Question 10

Example of extracting metal

Answer 10

Carbon + iron oxide —> carbon dioxide + iron

Question 11

What elements are reduced and oxidised in terms of oxygen when extracting metals?

Answer 11

More reactive element eg carbon displaces the less reactive metal from its oxide compound
It is therefore oxidised
Metal removed from its metal oxide compound so it’s reduced

Question 12

Oxidation in terms of electrons

Answer 12

Losing electrons

Question 13

Reduction in terms of electrons

Answer 13

Gaining electrons

Question 14

How to find what elements have been reduced or oxidised (electrons) in an equation?

Answer 14

Write the symbol equation
Write the ions part of each compound
Compare them to before and after the reaction happens

Question 15

Acids

Answer 15

pH below 7
Produce H+ ions when dissolved in water

Question 16

Examples of acids

Answer 16

Hydrochloric acid
Sulfuric acid
Nitric acid

Question 17

Formula for hydrochloric acid

Answer 17

HCl

Question 18

Formula for sulfuric acid

Answer 18

H₂SO₄

Question 19

Formula for nitric acid

Answer 19

HNO₃

Question 20

Reacting acids and metals

Answer 20

Acid + metal —> salt + hydrogen

Question 21

Displacement in terms of metals and acids reaction

Answer 21

More reactive metals than hydrogen displace the hydrogen in an acid
So copper doesn’t react

Question 22

What determines the rate of an acid metal reaction?

Answer 22

How more reactive a metal is compared to hydrogen
Therefore iron with an acid would be a slow reaction

Question 23

Acid metal redox reactions in terms of electrons

Answer 23

Metal is oxidised because it loses electrons to join with the salt
Hydrogen is reduced because it gains the electrons from the metal to become hydrogen atoms

Question 24

Is acid and metal a neutralisation reaction?

Answer 24

NO it is a redox and displacement reaction

Question 25

Redox reaction

Answer 25

= both oxidation and reduction happening at the same time

Question 26

Base

Answer 26

Chemicals that neutralise acids
Produce OH- ions in dissolved water
pH above 7

Question 27

Examples of bases

Answer 27

Metal oxides, metal hydroxides

Question 28

Alkalis

Answer 28

Special type of base that can dissolve in water

Question 29

Acid + base/alkali neutralisation

Answer 29

Acid + base —> salt + water

Question 30

Making a copper salt

Answer 30

Copper itself doesn’t react with dilute acids so we use copper oxides or carbonates

Question 31

Making a sodium/lithium/ potassium salt

Answer 31

Too dangerous to react with the metal on its own
We react it with a metal oxide or carbonate

Question 32

What shows a neutralisation has happened?

Answer 32

H⁺ + OH⁻ —> H₂O

Question 33

How does a neutralisation happen?

Answer 33

H+ from the acid and OH- from the base form H2O

Question 34

Identifying salts

Answer 34

Contains a negative ion from the acid eg Cl-
Contains positive ion from base eg Na+
Makes:
NaCl

Question 35

Acid and metal carbonate reaction

Answer 35

Acid + metal carbonate —> salt + water + carbon dioxide

Question 36

What determines a strong or weak acid?

Answer 36

Whether it fully ionises in water = strong acid
Whether it partially ionises in water = weak acid

Question 37

How can we tell if an acid only partially ionises?

Answer 37

Some hydrogen molecules in the compound don’t become H+
Or it’s a reversible reaction

Question 38

Concentrated acid

Answer 38

More acid molecules than water in a given volume

Question 39

Dilute acid

Answer 39

Less acid molecules than water in a given volume

Question 40

Strong acid in a dilute concentration

Answer 40

Fully ionising
But less H+ ions as a result of the water than if it was a concentrated solution
Therefore high pH

Question 41

Strong acid in a concentrated solution

Answer 41

Fully ionising
More H+ ions as there’s more acid molecules than water
Therefore lower pH

Question 42

Weak acid in a dilute solution

Answer 42

Partially ionising
Therefore not many H+ ions and there’s even less because there’s more water
Therefore higher pH

Question 43

Weak acid in a concentrated solution

Answer 43

Partially ionising
Not many H+ ions but slightly more because there’s more acid molecules than water
Therefore slightly lower pH than in a dilute solution

Question 44

What determines the pH of an acid?

Answer 44

How many H+ ions there are when dissolved in water in a given volume
More H+ ions = lower pH
Less H+ ions = higher pH

Question 45

If you decrease the pH by 1 how does that effect the number of H+ ions

Answer 45

X10 ions
One order of magnitude