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Chemistry Rate Of Reactions > Facts In Books > Flashcards

Facts In Books Flashcards

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1
Q

How does a catalyst work

A

They lower the activation energy as they provide an alternative pathway at a lower energy level so more successful collisions occur
^^ meaning they speed up reactions

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2
Q

What do catalysts do and not do

A

They speed up reactions but are not used up

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3
Q

What is the meaning of a reversible reaction

A

A reaction that can be changed back to its original form > the reaction can go in both directions

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4
Q

What is the collision theory

A

In a chemical reaction, reactant particles must collide and the colliding particles must have enough energy for the collision to be successful

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5
Q

Give 2 ways you can measure the rate of a reaction

A

Amount of reactant used up (divide) time
Or
Amount of product made (divide) time

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6
Q

What is the effect of temperature on rates

A

If increased the reactant particles move more quickly which means they have more energy and collisions happen more therefore the rate of reaction increases

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7
Q

What effect does a catalyst have on a rate of reaction

A

They lower the activation energy, providing a different pathway and a lower energy level so more successful collisions occur

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8
Q

What affect does the surface area have on rates of a reaction

A

The fate will increase as more particles are exposed to the other reactant and more collision will therefore happen

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9
Q

What is the effect of concentration/ pressure on rates of a reaction

A

More reactant particles in same volume so a greater chance for particles to collide and rate increased

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10
Q

What is the mass of a substances measured with

A

Balance

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11
Q

Volume of a gas is measured with?

A

Gas syringe or burette

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12
Q

What factored effect rates of a reaction

A 
Temperature change 
Concentration of a dissolved reactant 
Pressure of a reacting gas 
Surface area is changed 
Catalysts
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13
Q

Whats the activation energy

A

The minimum energy needed for particles to react

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14
Q

What does an iron catalyst do

A

Makes ammonia from nitrogen and hydrogen

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15
Q

What’s a platinum catalyst effect

A

Making ammonia from nitrogen and hydrogen

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16
Q

What is bond breaking

A

An endothermic reaction because energy must be supplied to break existing bonds

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17
Q

What is bond formation

A

Exothermic reaction because energy is released when new bonds are formed

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18
Q

How can you calculate the overall energy change for a reaction

A

Using bond energies

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19
Q

What’s the equation for energy change

A

Energy if bond breaking - energy if bond making

20
Q

How do you work out the amount of energy used in bond breaking

A

Adding up the bond energies of all the bonds in the reactants

21
Q

How do you work out the amount of energy given out from bond making

A

Adding up the bond energies of all the bonds in all the products

22
Q

Give some facts on ammonia

A

It breaks down when it is heated

It’s a colourless gas

23
Q

What happens when ammonium chloride breaks down

A

It firms ammonia gas and hydrogen chloride gas

24
Q

What is a closed system

A

When I ether reactants nor products can enter or leave

25
Q

What is the position of equilibrium

A

When reversible reactions reach a balance point, where the amount of reactants and the amount of products formed remain constant

26
Q

When is an equilibrium reached

A

When the forward and reverse reactions occur at the exactly same rate

27
Q

What is le chateliers principle

To do with dynamic equilibrium

A

If a dynamic equilibrium is disturbed by changing the conditions, the reaction moves to conteract change

28
Q

How is a does concentration change the position of equilibrium

A

If more of a reactant is added, the system would work by removing this reactant and making more of the products

29
Q

How does temperature change the position of equilibrium

A

Decreasing the temp moves the position of E in the direction of the exothermic reaction

Increasing the temp moves the position of E in the endothermic direction

30
Q

How does changing the pressure effect the post Position of equilibrium

A

Increasing the pressure moves the position of E to the suede with the least number of molecules

31
Q

What happens if you add a catalyst to an equilibrium reaction

A

It reduces the time to reach equilibrium but doesn’t change the position of E

32
Q

Why do particles need to smash into one another

A

So the bonds are broken and new substance is made

33
Q

What happens if activation energy is low

A

Particles don’t need to collide with much energy to react

Meaning they’ll react as soon as they’re mixed

34
Q

What does carbon dioxide produce during a reaction

A

Fizzing

35
Q

What’s is the concentration

A

Amount of molecules dissolved in a volume of water

36
Q

What can’t you do if two reactants are gases

And what the alternative thing to do

A

Increase the concentration

So you increase the pressure

37
Q

How can the rate of reaction between marble chips and hydrochloride acid be changed

A

Changing the temperature and surface area of reactants

38
Q

Why are powders like icing sugar flour and custard powder dangerous

A

They react very quickly as they have very large surface areas so they need to avoid naked flames

39
Q

What are the pros of catalysts

A

Very small amounts can be used and they can be used again and again thus many industrial chemical reactions use them

40
Q

What is a drawback if catalysts

A

They are very specific to what they can be used on

41
Q

What are catalysts in living things called

A

Enzymes

Sometimes known as biological catalysts

42
Q

Where do reactions stop

A

One or both of the reactants are used up

43
Q

What is the reactant called that causes the reactions to stop

A

Limiting reactant

44
Q

How to measure the rate of reaction on a graph on a fine point on the graph

A

Make a tangent (straight line) on the curve of where the point asked is
Then draw a right angles triangle and find the steepness of the tangent by dividing the height by the width
Thus = vol. gas collected (divided) time taken

45
Q

To measure reactions rates what do you need to do

A

Observe the reaction at time intervals
see amount of gas released
Change in mass
The colour or appearance change

Chemistry Rate Of Reactions (2 decks)

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