Frequently Wrong

Question 1

Standard enthalpy of hydration?

Answer 1

Enthalpy change when 1 mol of gaseous ions dissolve in sufficient water.

Question 2

Standard enthalpy of solution?

Answer 2

Enthalpy change when 1 mol of an ionic substance dissolves in sufficient water.

Question 3

What type of bonds is radiation absorbed by and what happens to the bonds?

Answer 3

Polar bonds; they rotate faster.

Question 4

Ester + aqueous sodium hydroxide (reflux)?

Answer 4

Alcohol + carboxylic acid
(HYDROLYSIS)

Question 5

What happens to pH and Kw as temperature increases?

Answer 5

The Kw increases, and so H+ ions also increase, so the pH decreases.

Question 6

How to obtain oil from mixture with solid?

Answer 6

• Filter
• Distil

Question 7

Reaction orders are for reactants/products?

Answer 7

Reactants

Question 8

When assessing a fuel, talk about (pros and cons):

Answer 8

Pros: recycling, prevents using landfill, renewable, carbon-neutral, fewer stages in production process (if applicable)
Cons: consider the yield, consider solvents used, non-renewable?, deforestation, high cost of transport, large scale plantations = habitat loss.

Question 9

When giving energy values include…

Answer 9

• the sign
• kJ mol^-1
• 3 s.f.

Question 10

Effect on delta Ssys when temperature changes?

Answer 10

NO EFFECT

Question 11

What is a diminishing peak and increasing ?

Answer 11

One that is “fading away” (NOT MS DEFINITION!)
Eg. it is for a bond found in the reactant, but the IR spectroscopy is showing for product, and that bond is not present there.
Increasing peak is the opposite.

Question 12

What is a partition coefficient?

Answer 12

The ratio of concentrations of a solute in two immiscible or slightly miscible liquids, or in two solids, when it is in equilibrium across the interface between them.

Question 13

Assumptions for buffer calculation

Answer 13

• Initial acid concentration = equilibrium acid concentration, as dissociation is very small
• Measurements are at standard temperature
• the ions that the acid dissociates into are of equal concentration/moles as they are 1:1 ratio.

Question 14

When describing effect on delta Ssurr…

Answer 14

MORE positive/negative
OR
LESS positive/negative

DO NOT SAY JUST DECREASES/INCREASES!

Question 15

Why is it important for clock reaction to have large excess of the ions?

Answer 15

So that they aren’t the limiting reactant.

Question 16

To work out activation energy for iodine clock reaction, what experimental measurements have to be made?

Answer 16

Temperature and time taken for the solution to turn blue-black.

Question 17

Why is ____ sparingly soluble?

Answer 17

L-forces between ____ and the solute molecules.

Question 18

Acid hydrolysis VS alkaline hydrolysis

Answer 18

Acid: reversible reaction, acid is a CATALYST not a reagent, carboxylic acid produced NOT SALT.
Alkaline: NaOH is a reagent, reaction goes to completion, salt of the carboxylic acid is formed.