Period 3 oxides 3.2.4 Flashcards
1
Q
When period 3 oxides burn in oxygen what do they form?
A
white solid oxides
2
Q
What is the reaction between sodium and oxygen?
A
4Na + O2 => 2Na2O
3
Q
What is the reaction between magnesium and oxygen ?
A
2Mg + 1/2O2 => MgO
4
Q
What is the reaction between aluminium and oxygen?
A
4Al + 3O2 => 2Al2O3
5
Q
What is the reaction between silicon and oxygen ?
A
Si + O2 => SiO2
6
Q
What is the reaction between phosphorus and oxygen ?
A
P4 + 5O2 => P4O10
7
Q
How does sodium react with water?
A
- Vigorously
- Forms a ball and fizzing
- Hydrogen gas is produced
8
Q
What is the reaction of sodium and water ?
A
2Na + 2H2O => 2NaOH + H2
9
Q
What is the reaction between sodium oxide and water?
A
Na2O + H2O => 2NaOH
10
Q
what’s the ph of sodium oxide?
A
14
11
Q
What’s the reaction between sodium oxide and acid?
A
Na2O + 2H+ => 2Na+ + H20
12
Q
what happens when magnesium reacts with water?
A
- reacts slowly
- forms a weak alkaline solution of magnesium hydroxide ( Mg(OH)2)
- this is a weak alkaline solution as magnesium hydroxide is sparingly soluble
13
Q
what’s the reaction of magnesium and water?
A
Mg + 2H2O => Mg(OH) + H2
14
Q
What’s the reaction between magnesium and steam?
A
Mg (s)+ H2O(g) => MgO (s) + H2(g)
15
Q
why is magnesium oxide less soluble than sodium oxide?
A
magnesium oxide has higher lattice enthalpy
16
Q
what’s the reaction between magnesium oxide and water?
A
Mgo + H2O => Mg(OH)2
17
Q
what’s the ph of magnesium oxide ?
A
10
18
Q
what’s the reaction between magnesium oxide and acid?
A
MgO + 2H+ => Mg2+ + H2O
19
Q
why is aluminium oxide insoluble?
A
very high lattice enthalpy
20
Q
what name is given to aluminium oxide
A
amphoteric
21
Q
what’s the reaction between aluminium oxide and acid?
A
Al2O3 + 6H+ => 2Al3+ + 3H2O
22
Q
what’s the reaction between aluminium oxide and hydrochloric acid?
A
Al2O3 + 6HCl => 2AlCl3 + 3H2O
23
Q
what’s the reaction between aluminium oxide and sodium hydroxide?
A
Al2O3 + 2NaOH + 3H2O => 2NaAl(OH)4
24
Q
why is silicon (IV) oxide insoluble (SiO2) ?
A
lattice of atoms linked by strong covalent bonds that would have to be broken
25
what’s the reaction between silicon oxide and an alkali?
SiO2 + 2OH- => SiO3- +H2O
26
what’s the reaction between phosphorus oxide and water?
P4O10 + 6H2O => 4H3PO4
27
what is the ph of phosphorus oxide and why?
-1 to +1
H2O molecules attach the S+ P atoms leading to the release of H+ ions from the water molecules
28
what’s the reaction between phosphorus oxide and alkali?
P4O10 + 12OH- => 4PO43- +6H2O
29
What happens when Sulfur oxide (SO2) reacts with water?
it dissolves
30
what’s the rection between sulfur oxide and water?
SO2 + H2O => H2SO3
31
what’s the ph of sulfur oxide and why?
1.3
H2O molecules attach to the S+ S atoms , leading to the release of H+ ions from the water molecules
32
what’s the reaction between sulfur oxide and alkali?
SO2 + 2OH- => SO3 2- + H2O
33
What happens when Sulfur (VI) oxide (SO3) reacts with water?
reacts violently
34
what’s the reaction between SO3 and water?
SO3 + H2O => H2SO4
35
what’s the ph of SO3 and why?
0
H2O molecules attach to the S+ S atoms , leading to the release of H+ ions from the water molecules
36
what’s the reaction between sulfur trioxide and hydroxide ?
SO3 + 2OH- => SO4 2- +H2O
37
what’s the trend in PH in period 3 oxides?
- Acidity increased from left to right
- Ranging from strongly basic oxides on the left to strongly acidic on the right
- with an amphoteric oxide in the middle
38
Why do Na2O , MgO and Al2O3 have high melting points?
- form giant ionic lattices
- giant ionic lattices have lots of strong attractive forces which require a lot of energy to break the bonds
39
why does MgO have a higher melting point than Na2O?
It forms 2+ ions and Na forms +1 ions.
The 2+ ions are attracted more strongly to the oxygen
40
Why does Al2O3 have a lower melting point than MgO?
- Al3+ ions distort the electron cloud of oxygen.
This means that there’s some covalent character as well as ionic interactions.
Less energy is required to break the bonds
41
Why does SiO2 have a higher melting point than the non metal oxides (P4O10 and SO2)?
- Forms a giant covalent structure.
Many strong covalent bonds which require lots of energy to break.
42
Why does P4O10 and SO4 have lower melting points than SiO2?
- They form simple molecular structure.
Weaker intermolecular forced so less energy required to break the bonds
43
why does the reaction of sodium oxide reacting with water forms a solution that is more alkaline?
Sodium oxide contains O 2- ions
O 2 - ions react with water forming OH- ions
44
what’s the equation for sulfur reacting with oxygen ?
S + O2 => SO2
45
what would you see if you react sulfur with oxygen ?
Brown fumes
46
what is the formula of the hydroxide of an element in period 3 that’s used in medicine
Mg(OH)2
47
what are the observations of sodium reacting with oxygen
- yellow or orange flame
- white fumes
48
what’s an observation for phosphorus reacting with oxygen
white fumes
49
which element form an ionic o code that reacts with strong alkalis
aluminium
50
what test tube reaction could you do to distinguish between sodium oxide and phosphorus oxide
- react with water
- add ph meter
- sodium oxide has a higher pH than phosphorus oxide
51
write an equation for the reaction of an excess of magnesium oxide with phosphoric acid
3 MgO + 2 H3PO4 => Mg3(PO4)2 + 3H2O
52
what’s an equation for aluminium oxide reacting with sulfuric acid
Al2O3 + 3H2SO4 => Al2(SO4) + 3H2O
53
what happens to aluminium oxide once it’s added to an excess of water
becomes insoluble
54
which element forms an oxide that has a low melting point and dissolves in water to form an acidic solution
phosphorus
55
reaction of sodium oxide with hcl
Na2O + 2HCl => 2NaCl + H2O
56
what are 2 equations you could use to show the amphoteric nature of aluminium oxide
aluminium oxide and hcl
aluminium oxide and acid
57
why do both sodium oxide and magnesium oxide form alkaline solutions
oxides react with water to produce hydroxide ions
58
why does sodium oxide form a solution with a higher pH then the solution formed from magnesium oxide
sodium hydroxide is more soluble than magnesium hydroxide
59
Reaction of phosphorus oxide with sodium hydroxide
P4O10 + 12NaOH => 4Na3PO4 + 6H2O
60
EQ : suggest why it’s dangerous tor react a similar piece of sodium with 10cm3 of water in a boiling tube (1)
Temp will go up
- mixture could explode
- H2 gas is flammable
61
explain in terms of crystal structure and bonding why silicon oxide has a higher melting point than phosphorus oxide (4)
- silicon oxide is a giant covalent structure
- Has many strong covalent bonds which are hard to break
- Phosphorus oxide is a molecular / simple covalent structure
- Has weak van de waals forces between molecules
62
EQ : explain the increase in melting point from sodium oxide to magnesium oxide (2)
- Mg2+ has a higher charge density
- Stronger attraction for the oxide ion / between oppositely charged ions / stronger ionic bonding
63
EQ : describe a test you could carry out in a test tube to distinguish between sodium oxide and phosphorus oxide (3)
- react with water
- Measure pH with pH meter
- Sodium oxide pH (12-14)
- Phosphorus oxide pH (-1 to 2)
64
Equation for reaction of an excess of magnesium oxide with phosphoric acid
3 MgO + 2H3PO4 => Mg3(PO4)2 + 3H2O
65
EQ : why is the melting point of sulfur (IV) oxide different from phosphorus (V) oxide (2)
SO2 is smaller than P4O10
VdW forces between molecules are weaker
66
EQ : explain why sodium oxide forms an alkaline solution when it reacts with water (2)
Sodium oxide contains O 2- ions
- O2 - ions react with water forming OH - ions
67
what are two physical properties of silicon dioxide that are characteristic of its structure and bonding
- Hard / Brittle
- Insoluble
- Non conductor
68
EQ : What type of bonding is in MgO. Outline a simple experiment to show this type of bonding (3)
Ionic
- Melt it
- Molten oxide conducts electricity
69
EQ : By reference to the structure of and the bonding in , silicon dioxide , suggest why it is insoluble in water (3)
- Macromolecular
- Covalent bonding
- Water cannot break covalent bonds
70
EQ : state how the melting point of P4O10 compared with that of SiO2 . Explain in terms of structure and bonding in P4O10 (3)
- lower melting point
- molecular with covalent bonding
- weak vdw forces between molecules
