1.7

Question 1

What is dynamic equilibrium

Answer 1

Forward and reverse reaction occur at the same rate

Question 2

What is position of equilibrium

Answer 2

Proportion of products of reactants in an equilibrium mixture

Question 3

What affects the position of equilibrium?

Answer 3

Concentration, pressure, temperature

Question 4

What doesn’t affect the position of equilibrium but helps reach equilibrium faster

Answer 4

Catalyst

Question 5

State Le Chatelier’s principle

Answer 5

If a system at equilibrium is subjected to a change, the equilibrium tends to shift so as to minimise the effect of the change

Question 6

If the concentration of a reactant is increased the position of equilibrium moves to the

Answer 6

Right

Question 7

Increasing the pressure moves the position of equilibrium to

Answer 7

Whichever side has fewer gas molecules

Question 8

An increase in temperature moves the position of equilibrium

Answer 8

In the endothermic direction

Question 9

What is an acid

Answer 9

Proton donor

Question 10

What is a base

Answer 10

Proton acceptor

Question 11

What is a strong acid

Answer 11

Fully dissociates in aqueous solution

Question 12

What is a weak acid

Answer 12

Partially dissociates in aqueous solution

Question 13

What is a concentrated acid

Answer 13

Consists of a large quantity of acid and a small quantity of water

Question 14

What is a dilute acid

Answer 14

Contains a large quantity of water

Question 15

Equation for pH

Answer 15

-log10[H+]

Question 16

What is a standard solution

Answer 16

One whose concentration is accurately known

Question 17

How is the point of neutralisation measured in an acid-base titration

Answer 17

Indicator

Question 18

What must a standard solution have

Answer 18

High purity
Stability
Low hygroscopicity
High molar mass

Question 19

How to prepare a standard solution

Answer 19

• calculate the mass of solid required and accurately weigh this amount into a weighing bottle
• transfer all of the solid into a beaker. Wash out the weighing bottle so that any residue runs into the beaker. Add water and stir until all the solid dissolves
• pour all the solution carefully through a funnel into a volumetric flask, washing all the solution out of the beaker and the glass rod. Add water until just below the graduation mark
• Add water drop by drop until the graduation mark is reached and mix the solution thoroughly

Question 20

How to perform a titration

Answer 20

• pour one solution into a burette, using a funnel, making sure that the jet is filled. Remove the funnel and read the burette
• use a pipette to add a measured volume of the other solution into a conical flask
• add a few drops of indicator to the solution in the flask
• run the acid from the burette to the solution in the conical flask, swirling the flask
• stop when the indicator just changes colour (end-point)
• read the burette again and subtract to find the volume of acid used (titre)
• repeat the titration, making sure that the acid is added drop by drop near the end-point, until you have at least 2 readings that are within 0.20cm3 of each other and calculate a mean titre

Question 21

Why would a back titration need to be used

Answer 21

Reaction between determined substance and titrant can be too slow, there can be a problem with end-point determination or the base is an insoluble salt

Question 22

What to do in back titration calculations
A= the known excess
B= unknown amount

Answer 22

• amount of A that has been used (starting amount-titre)

* amount of reagent B thats reacted

Question 23

When to do a double titration

Answer 23

If a solution contains a mixture of two bases which are of different strengths

Question 24

What is done differently in a double titration

Answer 24

Use of 2 different indicators at different stages to calculate the concentrations of both bases