Equbillria reactions

Question 1

Revisible reaction

Answer 1

Is a reaction that can go in either direction depending on the conditions

Question 2

Dynamic equilibrium

Answer 2

When the forward and reverse reactions occurred the same rate
Concentration of reactants and products remains the same
Dynamic equilibrium occurs in a closed system so no substances can get in or out in order to influence the reactionS
Concentration of reactants goes down from the top and concentration of products goes up from the bottom. as the concentrations reach steady values the equilibrium is established

Question 3

Water of crystallisation

Answer 3

Blue copper (ll) sulphate crystals have the formula CUSO4.5H2O
The water is called water crystallisation
When the copper sulphate is heated, the water of crystallisation is given off a steam leaving white powder called anhydrous copper (ll) sulphate
When water is added to the white powder, the powder gets hot and turns blue
CuSO4.5H2O –> CuSO4 + 5H2O
Blue —> white

Question 4

Haber process

Answer 4

Formation of ammonia from nitrogen and hydrogen
N2(g) + 3H2(g) —> 2NH3(g)

Question 5

Position of equilibrium

Answer 5

The proportion of products to reactants in an equilibrium mixture

Question 6

Le Chateliers Principle

Answer 6

States that if a system at equilibrium is subjected to a change to equilibrium tends to shift so as to minimise the effect of the change

Question 7

Effect of concentration change

Answer 7

eg. Increase of hydrochloric acid
Increasing H C L to a solution adds chloride ions, so the system will try to minimise this effect by decreasing the concentration chloride ions and so the position of equilibrium will move to the right and form more CuCl42- making the solution yellow green
Higher conc, lower yeild

Question 8

Affect the pressure change

Answer 8

Pressure of a gas depends on the number of molecules in a given volume of gas. Rated the number of molecules the greater the number of collision per unit time and therefore the greater the pressure of gas
If the total pressure is increased the equilibrium will shift to minimise this increase and the pressure will decrease if the equilibrium system contains fewer gas molecules therefore the position of equilibrium moves to the right
higher pressure lowe yeild

Question 9

Effecft of temperature change

Answer 9

If the temperature is increased the system will try and minimise this increase and the system opposes the changes by taking in heat or release in heat so the position of the equilibrium will move to the right or left depending on the enthaply change of the reaction

Question 10

Effect of catalysts

Answer 10

A catalyst will speed up the chemical reaction by lowering the activation energy of the reaction. Visible reaction a catalyst will increase the rate of the forward and backward reaction at the same extent so a catalyst doesn’t affect the position of equilibrium but the equilibrium is reached faster

Question 11

Acids

Answer 11

Proton (H+) donors
Go through the process of disassociating
Eg. HCl, H2SO4, HNO3, CH3CO2H

Question 12

Bases

Answer 12

Proton (H+) acceptors
Alkalis are bases
Can neutralise an acid of form as salt
Eg. NaOH, KOH, MgO, NH3

Question 13

Alkalis

Answer 13

they are bases that dissolving water to form OH- ions

Question 14

Strong and weak acids

Answer 14

Strong acids are ones that can fully disassociate in that clear solution, hydrogen ions are the same or more concentration as acid. Equilibrium lies to the right

Weak assets of those are partially dissociated accurate solution, aqueous hydrogen ions are less concentrated than acid. Equilibrium lies to the left

Question 15

iF Kc > 1

Answer 15

More products and reactants in equilibrium mixture, position of equilibrium lies to the right
The greater the value the further the equilibrium lives to the right

Question 16

if kc<1

Answer 16

More reacting sound products in equilibrium mixture, equilibrium lies to the left
Smaller value means equilibrium lies further to the left
Only change the temperature can change the unit value

Question 17

neutralisation equations

Answer 17

Acid + base = salt + water
Acid + aalkali = salt + water
Acid + carbonate= Salt + water + carbon dioxide

Question 18

Salt

Answer 18

Compound that forms when a metal ion replaces the H+ ion in an acid

Question 19

Standard solution

Answer 19

Solutions of a known concentration
Prepared using a primary standard

Question 20

Features of a primary standard

Answer 20

• High purity
• Stability, low reactivity
• Low hyperscopity, minimises weight change from humidity
• high molar mass, minimises weighIng errors

Question 21

Method of standard solution

Answer 21

• Calculate mass of solid required and accurately weigh this amount into a weighing bottle
• Transfer all the solid into a bigger, wash out the weighing bottle so that all the weighings run into the beaker. Water and stir until all solid itself
• Pull all the solution carefully through it funnel into a volumetric graduated flask, washing all solution off the beaker and the glass rod. Add water until just below the graduation mark

add water drop by drop until graduation mark is reached and mix solution thoroughly

Question 22

Acid base titration

Answer 22

Volume of one acid reacts with a known volume of one base
One of the solutions must be a standard solution or has been standardised

Question 23

indicaors

Answer 23

Marks end point

Question 24

Titration method

Answer 24

• Pour the acid into a bureaucrat using a funnel, making sure the jet is filled. Remove the funnel and Read burette
• Use a puppet to add a measure volume of the base in a conical fask
• Add a few drops of indicator to the solution in the flask
• Stop when the indicator just changes colour market and point of the tritation
• We’d be right again and subtract to find the volume of acid used known as titre
• Repeat titration making sure acid added drop by drop near the end point until there is at least two readings within 0.20cm

Question 25

Double titration

Answer 25

if a solution contains a mixture of two bases which are of different strengths a titian can be performed in 2 stages indicators

Question 26

concentraied acid

Answer 26

large amount of acid and small amount of water