Review Questions 1 & 2

Question 1

Under what conditions do sodium and sodium chloride conduct electricity and what is the method of conductivity in each case?

Answer 1

sodium - solid AND molten (delocalised electrons are charge carriers )
Sodium Chloride - molten (ions are charge carriers)

Question 2

Explain why the iodine bond length is larger than that of chlorine’s.

Answer 2

iodine has more shells of electrons and a larger atomic radium

so more shielding (of its nuclear charge)

so weaker attraction between the nucleus and bonding pair of electrons

Question 3

Explain why hydrogen fluoride can form hydrogen bonds but hydrogen bromide cannot

Answer 3

fluorine is more electronegative

fluorine has less shielding (so greater attraction between nucleus and bonding pair of electrons)

so the H-F bond is more polar than the H-Br bond

Question 4

Why can a small amount of UV light in free radical substitution form a large amount of product

Answer 4

because the free radical is recycled (it is reproduced in the propagation reactions so the reaction can keep on happening producing loads of the product)

Question 5

suggest two factors that would affect the rate of reaction of the solids in fireworks

Answer 5

temperature - more heat given off increases reaction rate because particles have more KE for the reaction

concentration - more tightly packed increases reaction rate because more particle-particle contact for the reaction

Question 6

less frequent collisions between …

Answer 6

the reactants

Question 7

Why does pressure have no effect on this reaction?

Answer 7

pressure only effects gaseous reactions

Question 8

When talking about thermal stability, remember they are

Answer 8

IONS

Question 9

Use the distributions to explain why gases react faster when the temperature is increased?

Answer 9

At T2 more molecules have energy greater than or equal to the activation energy (indicated by the larger area under the T2 to the right of Ea

and energy must be at least the activation energy for a successful reaction

Question 10

if you get the answer 0.00243 (recurring) do you round to 0.002 for your answer?

Answer 10

NO! Still put 0.00243 (recurring)

Question 11

If it tells you 3 moles of CO2 are produced when 20g of the IMPURE NaHCO3 sample is reacted then how do you work out the mass of just the pure stuff (the actual pure NaHCO3) within the impure sample?

Answer 11

So if 3 moles of CO2 was produced then (question tells us it is a 1:1 ratio) and so we know 3 moles of the pure NaHCO3 in the impure sample must have been what was burning because where else would the CO2 come from.

So we know there are 3 moles of PURE NaHCO3 then u can just do moles x rfm = to get mass of pure pure NaHCO3 within the impure sample.

Question 12

if you get the answer 0.0093 (recurring) how do you leave it for the answer?

Answer 12

0.009333

Question 13

CaCO3(s) + 2HCl(aq) —–> CaCl2(???) + H2O(l) + CO2 (g/aq)

Answer 13

CaCl2 is AQUEOUS (aq)

Question 14

In the coral question, why might the repeated experiments have inconsistent results?

Answer 14

because different samples of coral have different amounts of calcium carbonate

Question 15

If it asks you for a fragment of mass spec, remember to put a

Answer 15

+ SIGN !!

Question 16

Explain why a silver halide dissolving in CONCENTRATED ammonia to form a colourless solution does NOT prove conclusively that the halide was bromide?

And say an addition test that can be done to prove conclusively?

Answer 16

apparently both silver chloride and silver bromide give a colourless solution in concentrated ammonia

so instead you should add concentrated sulfuric acid to the silver halide and if the halide is bromide then you get a red-orange bromine gas

Question 17

How would you change the set up of a reflux apparatus if the reaction mixture needs stronger oxidising conditions to be converted to the desired product?

Answer 17

remove the thermometer

and place the condenser directly on top of the flask

Question 18

In mechanism questions when there is a C–halogen bond what should remember!!

Answer 18

Usually you should do the curly arrow going from the bond to the halogen!! You always forget this!