Chemsitry - Equillibrium Flashcards
If the forward reaction is ? (transfers energy from ? to the environment), the ? reaction will be endothermic (transfers ? from the ? to the reactants).
exothermic, reactants, backwards, energy, surroundings
The energy released/? by the forward ? will be exactly ? to the energy absorbed/? by the ? reaction
absorbed, reaction, equal, released, backwards
The concentrations of ? and products do ? change when a reaction is at ? equilibrium
reactants, not, dynamic
what will eventually be reached when reversible reactions happen within a closed system
Dynamic equilibrium
At dynamic equilibrium, how are the rates of the forwards and backwards reactions related?
they’re equal
why is equilibrium dynamic?
because both the forwards and backwards reactions are still taking place
what happens at equilibrium?
the rate of the forward reaction equals the rate of the backward reaction
how can the position of equilibrium be affected?
by changing the conditions in a reversible reaction
Le ? principle says that if any of the conditions of a ? reaction at equilibrium are changed, the ? system will ? to counteract whatever has ?
Chatelier’s, reversible, closed, adapt, changed
what can Le Chatelier’s principle be used for?
to predict the outcome of changes imposed on a system at equilibrium
what determines the relative amount of the substances involved in a reaction at equilibrium?
the conditions of the reaction
what does changing the temperature for a reaction at equilibrium do and what does the system do in response?
takes the system out of equilibrium. in response the system will try and restore equilibrium
what happens when the temperature decreases in equilibrium? (and what happens to the products)
the position of equilibrium shifts in the exothermic direction - meaning more products from exothermic reaction and less from endothermic reaction
what happens if there’s an increase in temperature in equilibrium and what happens to the products?
the position of equilibrium shifts in the endothermic direction - meaning more products from endothermic reaction and less from exothermic reaction
The position of equilibrium will shift towards the side of the reaction that produces the most gas molecules - when does this happen?
when the pressure is decreased
what happens at equilibrium if you increase the pressure?
the position of equilibrium will shift to favour the reaction that produces the least/ fewest gas molecules
how do we predict the outcome of a pressure change?
have to look at balanced equations to see how many gas molecules are on each side of the equation!!!
what does changing the concentration of any reactant or product do?
takes the system out of equilibrium. The system will react to try to restore the equilibrium
what does increasing the concentration of a reactant do?
favours the forward reaction - shifting the position of equilibrium towards the products
what happens if you increase the concentration of a product?
favours the backward reaction - shifting the position of equilibrium towards the reactants
what’s the backwards reaction?
when the equilibrium shifts towards the reactants
what’s the forwards reaction?
when equilibrium shifts towards the products
what’s the forwards reaction?
when equilibrium shifts towards the products
What happens when you increase the concentration of a product of a reversible reaction at equilibrium? (rate of reaction)
Rate of forwards reaction < rate of backwards reaction
What happens when you increase the concentration of a reactant of a reversible reaction at equilibrium?
Rate of forward reaction > rate of backwards reaction
ph of ammonia solution?
11
equation of the reversible reaction between ammonia and water
NH3 +H2O ⇌ NH4+ + OH-
what are the properties of ammonia and why?
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
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.
(chemical) reaction, up, alternative, pathway, activation, rate, forward, backward, amount, speed, equilibrium
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/?
position, left
exothermic, less, particles
opposes, increasing, pressure
what does Le Chatelier’s principle state?
When a change is made to a reaction in equilibrium, the position of equilibrium will shift to oppose the change.
what may fertilisers contain to promote plant growth?
nitrogen, phosphorus and potassium compounds
what are the 3 conditions for the Haber process?
- temperature - 450 degrees
- pressure - 200 atmospheres
- iron catalyst!
what is dynamic equilibrium?
when the forwards and backwards reactions are equal and still taking place in a reversible reaction!!
what is ammonia formed from and how are these gases extracted?
nitrogen (from the air) and hydrogen (from natural gas)
why can the reaction of nitrogen and hydrogen to form ammonia reach dynamic equilibrium?
as it is a reversible reaction.
chemical formula of ammonia and its bonding type???
NH3, covalent bonding
what 3 things is ammonia used to make?
Fertilisers, plastics, explosives
How is ammonia separated from unreacted chemicals?
Let it cool to -40 degrees - so ammonia will liquefy and run out the bottom, while nitrogen and hydrogen will remain as gases
What happens to the unreacted nitrogen and hydrogen in the haver process?
Recycled back into the reaction vessel
How to produce nitrogen from air?
Fractional distillation of liquid air - separates oxygen and nitrogen by boiling points
what conditions give the highest % of ammonia?
high pressure and low temperature
what is negative about using high pressures in the haber process
very expensive to build and run the plant and is also dangerous
Why is 450 degrees and 200ATM used in the haber process
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
Two reasons why the low yield in the haber process is NOT a problem?
Fast rate of reaction so yield achieved quickly
Reactants are recycled so no wasted H2 or N2
Why is nitrogen a gas at room temp ans why is it so UNreactive
Simple molecular - weak intermolecular forces require little energy to break
Has a triple bond so requires a lot of energy to break
Why are harmful NOx gases produced in a car engine
Car engine is very hot + gas is under v high pressure so reacts with oxygen
What do most plants require to supply their nitrogen intake
Soluble nitrogen compounds
What are natural sources of nitrogen compounds and why are they nit sufficient enough?
Manure and compost, but there’s not enough to support the earths growing temperature
Why can’t ammonia be used as a nitrogen fertilizer and what is the solution to this?
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
How is the reaction of acid and ammonia different from other Neutralisation reactions?
It doesn’t produce water, just the ammonium salt
Why are ammonium salts better than ammonia as fertilizers (3 reasons) :
- Not alkaline, are neutral
- Less toxic
- Not gases
Explain how to make a pure, dry sample of ammonium solution and nitric acid?
(Titration!)
- Use a glass Pipette to add 25cm3 of ammonia to a comical flask
- Add a few drops of methyl orange to turn it yellow
- Add nitric acid from burrette
—> swirl
—> add dropwise near end - Add end point methyl orange should go a (peachy) orange
- Repeat using same volumes but no indicator
- Evaporate water away by heating
- Leave to cool and crystallize
- Remove crystals by filtration
What is Phosporus (P) used for in crops
DNA, growth, healthy roots
What is Potassium (K) used for in crops
Fruiting and flowering
What is Nitrogen (N) used for in crops
Amino acids, proteins, DNA
Difference in scale of laboratory vs industrial manufacture of fertilizers?
L - milligrams
I - tonnes
Difference in safety of laboratory vs industrial manufacture of fertilizers?
L - safe due to low concentration
I - dangerous due to high pressure and concentration
Difference in equipment of laboratory vs industrial manufacture of fertilizers?
L - glassware
I - thick stainless steel container
Difference in conditions of laboratory vs industrial manufacture of fertilizers?
L - room temp and pressure
I - 60 degrees, high pressure
Difference in type of process of laboratory vs industrial manufacture of fertilizers?
L - batch
I - continuous (flow)
How would an increase in the price of natural gas affect the price of fertilizer?
Increases the price, as natural gas is needed to make hydrogen which is used in the haben process to make ammonia
Which compound - ammonium nitrate or sulfate would be a better value for a nitrogen fertilizer?
Ammonium nitrate as it has a higher percentage by mass of nitrogen (35% vs 21.21%) so it’s better value for money!!!
Why is potassium Phosphate called a P.K fertilizer?
As it is a compound containing both phosphorus and potassium
Name and formula of a compound which would be an N.K fertilizer???
KNO3 - potassium nitrate
Ammonium phosphate is an N.P fertilizer. Give the word and Symbol equation for its production..?
NH3 + H3PO4 —> (NH4)3PO4
Ammonia + phosphoric acid —> ammonium phosphate
Drawback of fertilizers?
Eutrophication- nutrients accumulate, leading to an excess in microorganisms , leading to a decreased amount of oxygen supply in water
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
- Fertilizers, rivers
- grows, water
- plants
- die, O2
- life, enough
- stinking
