Paper 2: Rates of reaction Flashcards

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1
Q

How is rate of reaction calculated

A

Reactant/product used or formed/time

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2
Q

Units for rate of reaction

A

g/s cm3/s or mol/s

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3
Q

3 ways of meausring rates of reaction

A

-Loss of mass of reactions
-Volume of gas produced
-Time for a solution to become opaque

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4
Q

Describe measuring rate by measuring mass loss

A

-Place reaction flask on balance
-A gas is given off, so record the decrease in mass in time intervals
-Plot a graph of mass vs time

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5
Q

Describe measuring rate by monitoring volume of gas

A

-Connect a gas syringe to a reaction flask and measure volume of gas formed in intervals
-Plot a graph of volume vs time

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6
Q

Describe measuring rate by monitoring the disappearance of a cross

A

-Take a piece of paper and mark a cross on it. Put reaction flask on this cross. Measure the reagants and measure how long it takes for a cloudy mixture to conceal a cross

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7
Q

How to find rate of reaction and some time from a graph

A

-Pick a point corresponding to the time, and find the tangent to the curve at this point
-The tangent is the gradient the steeper the tangent the faster the rate

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8
Q

Factors affecting rate of a chemical reaction

A

-Conc of reactants
-Pressure of gases
-Surface area
-Temperature
-Catalysts

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9
Q

What is collision theory

A

Chemical reactions can occur only when reacting particles collide with each other with sufficent energy

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10
Q

Effect of increasing temperature on rate of reaction

A

-Kinetic energy increases
-Particles move faster
-Collide more frequentley/higher chance of collisions

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11
Q

Effect of increasing concentration on rate of reaction

A

conc increases=faster reaction
more reactants=more frequent collisions

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12
Q

Effect of the increasing pressure of a gas on the rate of reaction

A

-Increases number of gas molecules so increases frequency of collisions and the rate of reaction

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13
Q

Effect of increasing the surface area on rate of reaction

A

-A greater surface area increases frequency of collisions and rate of reaction

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14
Q

How does a catalyst affect the reaction profile?

A

-increases reaction by providing a different pathway for a reaction that has a lower activation energy
-Reaction profile for a catalysed reaction will have a lower maximum of the curve (lower activation energy)

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15
Q

What is a reversible reaction

A

Reaction can react backwards to produce the original reactants

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16
Q

When is dynamic equilibrium reached

A

-When the forward and reverse reactions occur at the same rate and the concentrations of reactants and products remain constant

17
Q

Le Chatelier’s principle

A

If a system is at equilibrium and a change is made to any of the conditions, the system responds to conteract the change and restore equilibrium

18
Q

Effect of changing concentration of reactant and product on position of the equilibrium

A

-More products will be formed until equillibrium is reached again

19
Q

Effect of changing temperature of reactant and product on position of the equilibrium

A

-Amount of products increases for an endothermic reaction
-Amount of products decreases for an exothermic reaction

20
Q

Effect of changing Pressure of reactant and product on position of the equilibrium

A

-increase in pressure causes equilibrium to shift towards the side with smaller number of molecules

-decrease in pressure causes equilibrium to shift towards side with larger number of molecules

-No effect in number of molecules equal

21
Q

Effect of a cataylst on the position of equilibrium

A

No effect
Speeds up forwards and backward reactions equally