AQA GCSE Chemistry - Paper 2 Questions And Answers 100% Verified.
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AQA GCSE Chemistry - Paper 2
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AQA GCSE Chemistry - Paper 2
AQA GCSE Chemistry - Paper 2 Questions And Answers 100% Verified.
Mean rate of reaction (with reactant) - correct answer. Rate of reaction:
Quantity of reactant used
----------------------------
Time taken
Mean rate of reaction (with product) - correct answer. Rate of reactio...
AQA GCSE Chemistry - Paper 2 Questions
And Answers 100% Verified.
Mean rate of reaction (with reactant) - correct answer. Rate of reaction:
Quantity of reactant used
----------------------------
Time taken
Mean rate of reaction (with product) - correct answer. Rate of reaction:
Quantity of product formed
----------------------------
Time taken
Measurements for quantity of product or reactant - correct answer. Either as mass in g
or as volume in cm³
Measurements for the rate of reaction - correct answer. Either as g/s, cm³/s, or mol/s
Factors which affect rate of chemical reaction - correct answer. - *Temperature*: a
faster temperature means faster reaction
- *Concentration / pressure*: a higher concentration or pressure means a faster reaction
- *Surface area*: a larger surface area: volume ratio means a faster reaction
- *Catalysts*: a reaction in the presence of a catalyst is faster
Collision theory - correct answer. This states that a chemical reaction can only happen
when reacting particles collide with each other with enough energy.
Activation energy - correct answer. This is the minimum energy required for a reaction
to take place.
How surface area, concentration or pressure changes rate of reaction in terms of
collision theory - correct answer. This increases the frequency of collisions, as there
are more particles that are able to collide, increasing rate of reaction.
How temperature changes rate of reaction in terms of collision theory - correct answer.
This increases the frequency of collisions as well as the energy the collisions have,
increasing rate of reaction.
,Catalysts - correct answer. - A catalyst is a substance that changes the rate of
reaction
- It is not used up during the reaction, and therefore does not show up in the products or
reactants
- Different reactions require different catalysts, for example an enzyme
- The catalyst does this by supplying a different pathway to the reaction that requires a
lower activation energy, shown in the picture
Reversible reactions - correct answer. This is a reaction in which the products can
react to produce the original reactants
A+B⇌C+D
Example of a reversible reaction - correct answer. This reaction is reversible, meaning
the reactants can be heated to get the products as well as the products can be cooled
to get the reactants:
Ammonium chloride ⇌ ammonia + hydrogen chloride
Energy changes in reversible reactions - correct answer. If a reaction is endothermic
in one direction, it is exothermic in the other. The same amount of energy is transferred
each way.
Equilibrium in a reversible reaction - correct answer. If the apparatus are set up to
prevent the escape of reactants or products, an equilibrium can be reached, in which
the rate of forward and reverse reactions are the same. This will always occur in
consistent conditions.
The effect of changing concentration in a reversible reaction - correct answer. When
the concentration of one product or reactant is changed, the system is no longer at
equilibrium:
- If the concentration of the reactants is increased, more products are formed until a
balance is reached
- If the concentration of the products is increased, more reactants will form until a
balance is reached
The effect of increasing temperature in a reversible reaction - correct answer. When
the temperature is *increased*:
- More product is formed for an endothermic reaction
- Less product is formed for an exothermic reaction
The effect of decreasing temperature in a reversible reaction - correct answer. When
the temperature is *decreased*:
- Less product is formed for an endothermic reaction
- More product is formed for an exothermic reaction
, The effect of changing pressure in a reversible reaction - correct answer. For a
gaseous reaction at equilibrium:
- An increase in pressure causes the equilibrium position to shift towards the side of the
smaller number of moles, meaning whichever side has less moles, more of it will be
formed
- A decrease in pressure causes the equilibrium position to shift towards the side with
more moles, meaning whichever side has more moles, more of it will be formed
Hydrocarbon - correct answer. A hydrocarbon is a material that contains only carbon
and hydrogen atoms.
Alkanes - correct answer. - These are saturated, meaning there are only single bonds
between atoms
- They are relatively unreactive, although they do combust
- Their single bonds are quite strong
- They are a homologous series of hydrocarbons (organic compounds with the same
functional group and similar chemical properties)
- There are trends in their physical properties
Formula for alkanes - correct answer. Cn H2n+2
The first four alkanes - correct answer. - Methane
- Ethane
- Propane
- Butane
Formula for methane - correct answer. CH₄
Formula for ethane - correct answer. C₂H₆
Formula for propane - correct answer. C₃H₈
Formula for butane - correct answer. C₄H₁₀
Crude oil - correct answer. - A finite resource found in rocks
- Mostly ancient biomass, e.g. plankton, which has been buried in mud
- It is a mixture of many compounds, mostly hydrocarbons, which are mostly alkanes
- They are separated by fractional distillation
Why fractional distillation works - correct answer. The hydrocarbons in crude oil can
be separated into fractions, which are chemicals that have a similar boiling point. These
are molecules with a similar number of carbon atoms. Each fraction has different
properties and uses, a lot of which are processed to produce fuels and feedstock for the
petrochemical industry, e.g. petrol, kerosene, heavy fuel oil and liquefied petroleum
gases.
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