Chemsitry - Equillibrium

Question 1

If the forward reaction is ? (transfers energy from ? to the environment), the ? reaction will be endothermic (transfers ? from the ? to the reactants).

Answer 1

exothermic, reactants, backwards, energy, surroundings

Question 2

The energy released/? by the forward ? will be exactly ? to the energy absorbed/? by the ? reaction

Answer 2

absorbed, reaction, equal, released, backwards

Question 3

The concentrations of ? and products do ? change when a reaction is at ? equilibrium

Answer 3

reactants, not, dynamic

Question 4

what will eventually be reached when reversible reactions happen within a closed system

Answer 4

Dynamic equilibrium

Question 5

At dynamic equilibrium, how are the rates of the forwards and backwards reactions related?

Answer 5

they’re equal

Question 6

why is equilibrium dynamic?

Answer 6

because both the forwards and backwards reactions are still taking place

Question 7

what happens at equilibrium?

Answer 7

the rate of the forward reaction equals the rate of the backward reaction

Question 8

how can the position of equilibrium be affected?

Answer 8

by changing the conditions in a reversible reaction

Question 9

Le ? principle says that if any of the conditions of a ? reaction at equilibrium are changed, the ? system will ? to counteract whatever has ?

Answer 9

Chatelier’s, reversible, closed, adapt, changed

Question 10

what can Le Chatelier’s principle be used for?

Answer 10

to predict the outcome of changes imposed on a system at equilibrium

Question 11

what determines the relative amount of the substances involved in a reaction at equilibrium?

Answer 11

the conditions of the reaction

Question 12

what does changing the temperature for a reaction at equilibrium do and what does the system do in response?

Answer 12

takes the system out of equilibrium. in response the system will try and restore equilibrium

Question 13

what happens when the temperature decreases in equilibrium? (and what happens to the products)

Answer 13

the position of equilibrium shifts in the exothermic direction - meaning more products from exothermic reaction and less from endothermic reaction

Question 14

what happens if there’s an increase in temperature in equilibrium and what happens to the products?

Answer 14

the position of equilibrium shifts in the endothermic direction - meaning more products from endothermic reaction and less from exothermic reaction

Question 15

The position of equilibrium will shift towards the side of the reaction that produces the most gas molecules - when does this happen?

Answer 15

when the pressure is decreased

Question 16

what happens at equilibrium if you increase the pressure?

Answer 16

the position of equilibrium will shift to favour the reaction that produces the least/ fewest gas molecules

Question 17

how do we predict the outcome of a pressure change?

Answer 17

have to look at balanced equations to see how many gas molecules are on each side of the equation!!!

Question 18

what does changing the concentration of any reactant or product do?

Answer 18

takes the system out of equilibrium. The system will react to try to restore the equilibrium

Question 19

what does increasing the concentration of a reactant do?

Answer 19

favours the forward reaction - shifting the position of equilibrium towards the products

Question 20

what happens if you increase the concentration of a product?

Answer 20

favours the backward reaction - shifting the position of equilibrium towards the reactants

Question 21

what’s the backwards reaction?

Answer 21

when the equilibrium shifts towards the reactants

Question 22

what’s the forwards reaction?

Answer 22

when equilibrium shifts towards the products

Question 23

what’s the forwards reaction?

Answer 23

when equilibrium shifts towards the products

Question 24

What happens when you increase the concentration of a product of a reversible reaction at equilibrium? (rate of reaction)

Answer 24

Rate of forwards reaction < rate of backwards reaction

Question 25

What happens when you increase the concentration of a reactant of a reversible reaction at equilibrium?

Answer 25

Rate of forward reaction > rate of backwards reaction

Question 26

ph of ammonia solution?

Answer 26

11

Question 27

equation of the reversible reaction between ammonia and water

Answer 27

NH3 +H2O ⇌ NH4+ + OH-

Question 28

what are the properties of ammonia and why?

Answer 28

low melting point, non conductive, gas at room temperature - this is because of its weak intermolecular forces between molecules, and there are no delocalized electrons for conduction

Question 29

what do catalysts do? speed up the (?) ? without being used ?. they work by providing an ? route/ ? with lower ? energy. they do not affect the ? of equilibrium, as they speed up both the ? and the reverse/? reactions by the same ?. however, they do ? up the rate at which ? is reached.

Answer 29

(chemical) reaction, up, alternative, pathway, activation, rate, forward, backward, amount, speed, equilibrium

Question 30

3 steps of answering equilibrium questions: 1. state whether the ? of equilibrium has shifted ? or right 2. state why, e.g. endothermic or ? direction, more/? gas ? etc 3. state that this ? the change of ?/decreasing temp/?

Answer 30

position, left exothermic, less, particles opposes, increasing, pressure

Question 31

what does Le Chatelier's principle state?

Answer 31

When a change is made to a reaction in equilibrium, the position of equilibrium will shift to oppose the change.

Question 32

what may fertilisers contain to promote plant growth?

Answer 32

nitrogen, phosphorus and potassium compounds

Question 33

what are the 3 conditions for the Haber process?

Answer 33

- temperature - 450 degrees - pressure - 200 atmospheres - iron catalyst!

Question 34

what is dynamic equilibrium?

Answer 34

when the forwards and backwards reactions are equal and still taking place in a reversible reaction!!

Question 35

what is ammonia formed from and how are these gases extracted?

Answer 35

nitrogen (from the air) and hydrogen (from natural gas)

Question 36

why can the reaction of nitrogen and hydrogen to form ammonia reach dynamic equilibrium?

Answer 36

as it is a reversible reaction.

Question 37

chemical formula of ammonia and its bonding type???

Answer 37

NH3, covalent bonding

Question 38

what 3 things is ammonia used to make?

Answer 38

Fertilisers, plastics, explosives

Question 39

How is ammonia separated from unreacted chemicals?

Answer 39

Let it cool to -40 degrees - so ammonia will liquefy and run out the bottom, while nitrogen and hydrogen will remain as gases

Question 40

What happens to the unreacted nitrogen and hydrogen in the haver process?

Answer 40

Recycled back into the reaction vessel

Question 41

How to produce nitrogen from air?

Answer 41

Fractional distillation of liquid air - separates oxygen and nitrogen by boiling points

Question 42

what conditions give the highest % of ammonia?

Answer 42

high pressure and low temperature

Question 43

what is negative about using high pressures in the haber process

Answer 43

very expensive to build and run the plant and is also dangerous

Question 44

Why is 450 degrees and 200ATM used in the haber process

Answer 44

Is a compromise of temp - as it gives a medium rate with medium yield A compromise of pressure as it is less expensive but still gives a relatively good yield

Question 45

Two reasons why the low yield in the haber process is NOT a problem?

Answer 45

Fast rate of reaction so yield achieved quickly Reactants are recycled so no wasted H2 or N2

Question 46

Why is nitrogen a gas at room temp ans why is it so UNreactive

Answer 46

Simple molecular - weak intermolecular forces require little energy to break Has a triple bond so requires a lot of energy to break

Question 47

Why are harmful NOx gases produced in a car engine

Answer 47

Car engine is very hot + gas is under v high pressure so reacts with oxygen

Question 48

What do most plants require to supply their nitrogen intake

Answer 48

Soluble nitrogen compounds

Question 49

What are natural sources of nitrogen compounds and why are they nit sufficient enough?

Answer 49

Manure and compost, but there’s not enough to support the earths growing temperature

Question 50

Why can’t ammonia be used as a nitrogen fertilizer and what is the solution to this?

Answer 50

As it is alkaline and easily escapes from the soil as a gas, but it can be made into a suitable fertilizer by reacting it with an acid

Question 51

How is the reaction of acid and ammonia different from other Neutralisation reactions?

Answer 51

It doesn’t produce water, just the ammonium salt

Question 52

Why are ammonium salts better than ammonia as fertilizers (3 reasons) :

Answer 52

1. Not alkaline, are neutral 2. Less toxic 3. Not gases

Question 53

Explain how to make a pure, dry sample of ammonium solution and nitric acid? (Titration!)

Answer 53

1. Use a glass Pipette to add 25cm3 of ammonia to a comical flask 2. Add a few drops of methyl orange to turn it yellow 3. Add nitric acid from burrette —> swirl —> add dropwise near end 4. Add end point methyl orange should go a (peachy) orange 5. Repeat using same volumes but no indicator 6. Evaporate water away by heating 7. Leave to cool and crystallize 8. Remove crystals by filtration

Question 54

What is Phosporus (P) used for in crops

Answer 54

DNA, growth, healthy roots

Question 55

What is Potassium (K) used for in crops

Answer 55

Fruiting and flowering

Question 56

What is Nitrogen (N) used for in crops

Answer 56

Amino acids, proteins, DNA

Question 57

Difference in scale of laboratory vs industrial manufacture of fertilizers?

Answer 57

L - milligrams I - tonnes

Question 58

Difference in safety of laboratory vs industrial manufacture of fertilizers?

Answer 58

L - safe due to low concentration I - dangerous due to high pressure and concentration

Question 59

Difference in equipment of laboratory vs industrial manufacture of fertilizers?

Answer 59

L - glassware I - thick stainless steel container

Question 59

Difference in conditions of laboratory vs industrial manufacture of fertilizers?

Answer 59

L - room temp and pressure I - 60 degrees, high pressure

Question 60

Difference in type of process of laboratory vs industrial manufacture of fertilizers?

Answer 60

L - batch I - continuous (flow)

Question 61

How would an increase in the price of natural gas affect the price of fertilizer?

Answer 61

Increases the price, as natural gas is needed to make hydrogen which is used in the haben process to make ammonia

Question 62

Which compound - ammonium nitrate or sulfate would be a better value for a nitrogen fertilizer?

Answer 62

Ammonium nitrate as it has a higher percentage by mass of nitrogen (35% vs 21.21%) so it’s better value for money!!!

Question 63

Why is potassium Phosphate called a P.K fertilizer?

Answer 63

As it is a compound containing both phosphorus and potassium

Question 64

Name and formula of a compound which would be an N.K fertilizer???

Answer 64

KNO3 - potassium nitrate

Question 65

Ammonium phosphate is an N.P fertilizer. Give the word and Symbol equation for its production..?

Answer 65

NH3 + H3PO4 —> (NH4)3PO4 Ammonia + phosphoric acid —> ammonium phosphate

Question 65

Drawback of fertilizers?

Answer 65

Eutrophication- nutrients accumulate, leading to an excess in microorganisms , leading to a decreased amount of oxygen supply in water

Question 66

Steps of eutrophication: 1. ? washed into ? / canals 2. Algae ? and covers surface of ? 3. Sunlight is unable to reach ? 4. Plants ?, so less ? in water 5. Aquatic animal ? dies as there isn’t ? O2 6. Dead, ? stretch of water

Answer 66

1. Fertilizers, rivers 2. grows, water 3. plants 4. die, O2 5. life, enough 6. stinking