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Question 1

Carbonate test:-

Answer 1

Effervescenece when HNO3 is added.

Question 2

Use of avogadro’s number:-

Answer 2

Convert moles to molecules

Question 3

Sulfate test:-

Answer 3

Add Ba(NO3)2 solution. Observation = white solid.

Question 4

2 hydrolysis methods:1

Answer 4

1) heat with NaOH solution.

2) heat with H2O

Question 5

NaOH method of hydrolysis:-

Answer 5

Faster but can’t also test for bond enthalpy strength of C-X because OH+Ag-> AgOH(unwanted grey solid)
Faster because :OH^- is a stronger nucleophile w/ lone pair and a negative charge.

Question 6

H2O method:-

Answer 6

Slower but can also add AgNO3 and ethanol to test C-X bond enthalpy. Slower because weaker nucleophile as has no negative charge.

Question 7

Nucleophilic substitution mechanism:-

Answer 7

1. Draw dipoles on C-C.
2. Draw :OH^- (nucleophile) with a lone pair and negative charge.
3. Draw a curly arrow from the lone pair of :OH^- towards C. The electron pair forms a bond with the carbon atom.
4. Heterolytic fission of C-X occurs and :Br^- leaves (boyh electrons in covalent bond C-Br go to form :Br^-).
   Alcohol formed

Question 8

CF2Cl2:-(5)

Answer 8

Unreactive- electronegative so pulls electrons away from Cl.
Doesn't burn.
Easily compressed into liquid.
Good solvent.
Thought to be safe originally.

Question 9

Ozone:-

Answer 9

O3, good at absorbing radiation.

Question 10

Ozone/CF2Cl2 equations (similar to radical substitution):-

Answer 10

CF2Cl2 ->(UV) •CF2Cl + Cl• HOMOLYTIC FISSION.

O3+ Cl• -> •OCl + O2}
•OCl + O -> •Cl + O2 }Chain reaction
Ionic = O3 +O-> 2O2
Cl=homogeneous catalyst.

Question 11

Oxidation states in peroxides:-

Answer 11

H2O2
H= +1
O= -1

Question 12

H oxidation state in metal hydrides:-

Answer 12

MH
H= -1
H written at end.

Question 13

% error:-

Answer 13

(+- value from manufacturers / value we have measured) x100

When working out for deltaT, top value as there is error in initial and final.

Question 14

Heating to constant mass:-

Answer 14

Ensures all water of water of crystallisation is driven off

Question 15

Show dative covalent bond in displayed:-

Answer 15

Arrow from donating