Chem P1

Question 1

What is a standard solution?

Answer 1

A solution of known, accurate concentration.

Question 2

What are the drawbacks/ issues with chlorinating drinking water

Answer 2

1. Chlorine is toxic
2. Forms halogenated hydrocarbons
3. Forms carcinogens/ toxic compounds.

Question 3

What is disproportionation?

Answer 3

A reaction where an ELEMENT is both oxidised and reduced.

Question 4

Why does group 1/2 reactivity increase down the group

Answer 4

All normal points e.g. increased radius, shielding, decreased attraction etc.
Final point: therefore ionisation energy decreases!

Question 5

How can gibbs free energy be written in a linear graph form?

Answer 5

Can be written in form y=mx+c
y= Delta G
m= - Delta S
x= Temp
c= Delta H

Question 6

What always needs to be included in question on entropy change?

Answer 6

Talk about DISORDER- Higher in the products or the reactants?

Question 7

When proposing a two step mechanism, which step needs to come first?

Answer 7

The SLOW step (RDS)

Question 8

How do you calculate the “percentage dissociation” of a weak acid?

Answer 8

[H+]/[HA] x100

Question 9

What do you need to watch out for when arrhenius equation is plotted on a graph?

Answer 9

Units/ scale e.g. ( x10^-3)

Question 10

What is the general form of a two step mechanism?

Answer 10

Slow: Reactants in rate equation –> Intermediate
Fast: Intermediate + Reactants not in rate equation –> Products.

Question 11

What’s the answer when asked what block an element is in
Example: Sodium

Answer 11

Answer: The block AND the subshell which the highest energy electron is in.
E.g. Sodium is in S block, it’s highest energy electron is in 3S2

Question 12

How does pH of Grp 2 Hydroxides change as you go DOWN group 2

Answer 12

The pH Increases (becomes more alkali)

Question 13

State (again) and explain the change in pH of metal hydroxides down Grp 2

Answer 13

pH increases (becomes more alkali) because :
* They become more soluble as you go down the group.
* This is explained by decrease in lattice enthalpy of the hydroxide salt, and increase in coordination number of the metal ion.

Question 14

How does Oxygen bind to haemoglobin?

Answer 14

O2 gas can bind with Fe2+ ion found in the middle of haem groups.
This forms oxyhaemoglobin

Question 15

What can also bind to haemoglobin?

Answer 15

Carbon dioxide (CO2) and Carbon monoxide (CO)

Question 16

What happens when CO is breathed in?

Answer 16

Ligand substitution reaction takes place O2 in Hb is replaced by CO

Question 17

Why is CO Dangerous?

Answer 17

CO binds very strongly with Hb, more strongly than O2 so prevents O2 from binding.
Bond is so strong that it is irreversible.
Too high levels of carboxyhaemoglobin can lead to death.

Question 18

In a titration, why may just a small concentration be used?

Answer 18

So that the titre volume increases, which leads to a lower percentage uncertainty.

Question 19

What is the difference of BPs between HBr and HI a result of and why?

Answer 19

Stronger Induced dipole-dipole interactions (London forces), due to a difference in size and so a difference in no. of electrons.

Question 20

What do you need to remember to do when Making up a 250cm^3 standard solution.

Answer 20

1. When you are transferring solution from beaker to volumetric flask, ensure to rinse the sides of the beaker into the flask so no solution remains in the beaker.
2. When you are making the solution up to the 250cm^3 mark, invert several times to ensure solution is thorougly mixed.

Question 21

What is the structure of cisplatin

Answer 21

Question 22

When given a reaction equation and a value of k with units, how can you work out the overall order of the reaction?

Answer 22

Using the units of k to work it out. (work backwards)

Question 23

What is “weighted mean mass”

Answer 23

The mean mass taking into account the relative abundance of the isotopes

Question 24

When trying to work out the order of reaction with respect to a reactant, why may a large excess of the other reactant be used?

Answer 24

• To keep the concentration of the other reactant constant.
• So the reaction is 0 order wrt the other reactant
• To ensure equilibrium is far to the right

Question 25

Benefit of using chlorine in water treatment

Answer 25

Kills bacteria/ microorganisms

Question 26

What happens when HCl is added to AgNO3(aq)?

Answer 26

White precipitate forms

Question 27

What is the structure of silicon

Answer 27

Giant covalent lattice
Does not contain intermolecular forces

Question 28

Why is second ionisation of an element greater than first ionisation energy?

Answer 28

• When first electron is removed, cation forms
• Second electron removed from cation, greater nuclear attraction between cation and outer electrons

Question 29

In exothermic reaction, with fewer gas mol on RHS. Why is it difficult to predict how the changes affect the amount of product formed?

Answer 29

Increased temp, increased pressure:
Temp shifts Eq left, Pressure right.
It is difficult to determine the relative contributions of the two opposing factors

Question 30

Why do strong acids react quicker than weak acids?

Answer 30

• In strong acids, there is greater [H+]–> therefore more frequent collisions, therefore faster rate of reaction.

Question 31

Monobasic acid

Answer 31

One mole of acid dissociates to form one mole of H+

Question 32

Colour change at end point of MnO4-/Mn2+ titration.

Answer 32

Colourless –> Pale purple

Question 33

What colour is methyl orange at end point

Answer 33

Orange

Question 34

What colour is methyl orange when acid

Answer 34

Red

Question 35

What colour is methyl orange when conjugate base

Answer 35

Yellow

Question 36

What pH range does methyl orange work over

Answer 36

Acidic- roughly 3-4 pH

Question 37

Colour change of phenolphthalein

Answer 37

Colourless- pink