Period 3 and their oxides

Question 1

Describe the general pattern of first ionisation energies across period 3

Answer 1

Generally increases, though decreases from:
Mg to Al
P to S

Question 2

A period 3 element reacts with cold water to produce hydrogen gas and a hydroxide. Which element is it?

Answer 2

Na

Question 3

A period 3 element reacts with cold water to produce hydrogen gas and a hydroxide, but only very slowly. Which element is it?

Answer 3

Mg

Question 4

Mg reacts with cold water to produce hydrogen gas and a hydroxide. When it reacts steam, the products are slightly different. What are they?

Answer 4

MgO and hydrogen has

Question 5

Give an equation to show the reaction between Na and cold water

Answer 5

2Na (s) + 2H2O (l) –> 2NaOH (aq) + H2 (g)

Question 6

Is the reaction between Na and cold water fast or slow?

Answer 6

Fast

Question 7

Is the reaction between Mg and cold water fast or slow?

Answer 7

Very slow

Question 8

Give an equation to show the reaction between Mg and cold water

Answer 8

2Mg (s) + 2H2O (l) –> 2Mg(OH)2 (aq) + H2 (g)

Question 9

Give an equation to show the reaction between Mg and steam

Answer 9

Mg (s) + H2O (g) –> MgO (s) + H2 (g)

Question 10

What is formed when period 3 elements react with oxygen?

Answer 10

Their oxides

Question 11

An element is reacted with oxygen. It burns with a yellow flame to produce a white solid. What is the element?

Answer 11

Na

Question 12

An element is reacted with oxygen. It burns with a white flame to produce a white solid smoke. What is/are the elements?

Answer 12

Mg, Al, Si and P

Question 13

An element is reacted with oxygen. It burns with a blue flame to produce an acidic choking gas. What is the element?

Answer 13

S

Question 14

Give an equation to show the reaction of O2 and Na

Answer 14

4Na (s) + O2 (g) –> 2Na2O (s)

Question 15

Give an equation to show the reaction of O2 and Mg

Answer 15

2Mg (s) + O2 (g) –> 2MgO (s)

Question 16

Give an equation to show the reaction of O2 and Al

Answer 16

4Al (s) + 3O2 (g) –> 2Al2O3 (s)

Question 17

Give an equation to show the reaction of O2 and Si

Answer 17

Si + O2 (g) –> SiO2 (s)

Question 18

Give an equation to show the reaction of O2 and P

Answer 18

4P + 5O2 (g) –> P4O10 (s)

Question 19

Give an equation to show the reaction of O2 and S

Answer 19

S + O2 (g) –> SO2 (g)

Question 20

Sodium and phosphorous will react with air to form their oxides. How are they stored to prevent this?

Answer 20

Na in oil

P under water

Question 21

Describe and explain which oxide out of P4O10 and SO2 has the higher melting point

Answer 21

P4O10 has the higher melting point

Bigger molecule and so will have larger Van der Waals forces

Question 22

Why does aluminium metal not corrode?

Answer 22

It is protected by a thin layer of Al2O3 (s)

It has a high lattice strength and is insoluble, so is impermeable to air and water

Question 23

Give an equation to show the reaction between water and Na2O

Answer 23

Na2O + H2O –> 2Na+ (aq) + 2OH- (aq)

Question 24

Give an equation to show the reaction between water and MgO

Answer 24

MgO + H2O –> Mg(OH)2 (s)

Question 25

Give an equation to show the reaction between water and Al2O3

Answer 25

Doesn't react | Ionic lattice too strong

Question 26

Give an equation to show the reaction between water and SiO2

Answer 26

Doesn't react | Macromolecular structure - strong covalent bonds

Question 27

Give an equation to show the reaction between water and P4O10

Answer 27

P4O10 + 6H2O --> 4H3PO4 (aq)

Question 28

Give an equation to show the reaction between water and SO2

Answer 28

SO2 +H2O --> H2SO3 (aq)

Question 29

Give an equation to show the reaction between water and SO3

Answer 29

SO3 + H2O --> H2SO4

Question 30

A metal oxide reacts with water to give product(s) with pH 13. What is the metal oxide?

Answer 30

Na2O

Question 31

A metal oxide reacts with water to give product(s) with pH 9. What is the metal oxide?

Answer 31

MgO

Question 32

Both MgO and Na2O react with water to give alkaline products. However, the pH of the MgO product is pH9, whilst the pH of the Na2O product is pH13. Why is MgO's lower?

Answer 32

MgO has a higher lattice strength, and so is only slightly soluble in water. This means fewer free OH- ions are produced

Question 33

A metal oxide reacts with water to give product(s) with pH 0. What is/are the metal oxides?

Answer 33

P4O10 and SO3

Question 34

A metal oxide reacts with water to give product(s) with pH 3. What is the metal oxide?

Answer 34

SO2

Question 35

Give an equation to show the ions formed in solution when SO2 reacts with water

Answer 35

SO2 + H2O --> H+ + HSO3-

Question 36

Give an equation to show the ions formed in solution when SO3 reacts with water

Answer 36

SO3 + H2O --> H+ + HSO4-

Question 37

Al2O3 is amphoteric. Give two ionic equations to show this

Answer 37

Al2O3 + 6H+ --> 2Al3+ + 3H2O (as an acid) | Al2O3 + 2OH- + 3H2O --> 2Al(OH)4- (aq)