The rate and extent of Chemical changes Flashcards

1
Q

What side are the Products?

A

Right

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2
Q

What side are the Reactants?

A

Left

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3
Q

What is the Collision Theory?

A

It states for a chemical reaction to happen the reacting particles have to collide with each other with activation energy for a reaction to take place.

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4
Q

What is Activation Energy?

A

The minimum amount of energy that particles must have to react

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5
Q

What are the 5 main factors affecting rate of reactions?

A

1) Temperature
2) Concentration
3) Pressure
4) Surface area
5) Catalysts

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6
Q

What is temperature?

A

It is a measurement of how hot something is.

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7
Q

What is Concentration?

A

Is a measurement of the number of particles dissolved in a given volume solvent.

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8
Q

What is Pressure?

A

Is a measurement of the number of particles in a given volume of gas.

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9
Q

What is Surface area?

A

Is the total area of all surfaces of a substance.

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10
Q

What is Catalysts?

A

Is a substance that speeds up a chemical reaction without being used up.

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11
Q

How does Temperature affect rate of reaction?

A

If you increase the temperature, you increase the Kinetic energy of particles
This means that the particles move more frequently and rapidly
Meaning particles are more likely to collide with activation energy.

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12
Q

How does Concentration affect rate of reaction?

A

If you increase the concentration of the reactant in the solution, it will increase the number of particles
This means that there are more frequent collisions.

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13
Q

How does Pressure affect rate of reaction?

A

If you increase the pressure of a reaction in a gas, there will be a increase of particles
Meaning particles move more closely with each other, which increases frequency of collisions.

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14
Q

How does Surface Area affect rate of reaction?

A

If you increase the surface area of a solid reactant this will increase the frequency of collisions.

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15
Q

How does Catalysts affect rate of reaction?

A

A catalysts speeds up a reaction without interfering wit h the reaction and isn’t used up.
For catalysts to work they all decrease the activation energy needed for a reaction to occur. So lower activation energy=Higher rate of reaction.

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16
Q

What are 2 equations of rates of reactions?

A

RoR=quantity of reactant formed/time taken

RoR=quantity of product formed/time taken

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17
Q

What are the 3 main ways to measure rates of reactions?

A

1) Change in mass(Usually given off)
2) Precipitation and colour change
3) The volume of gas given off

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18
Q

What equation do you use to find out Change in mass?

A

RoR=quantity of product formed/time taken

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19
Q

What equation do you use to find out the volume of gas given off?

A

RoR=quantity of reactant formed/time taken

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20
Q

What is the equation of Precipitation and Colour change

A

1/time or 0/time

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21
Q

What is the method for the Experiment of Magnesium and HCI reacting to produce Hydrogen?

A

1) Pour dilute Hydrochloric acid into a conical flask and carefully place on mass balance.
2) Add some magnesium ribbon to the acid then after put cotton wool in the conical flask.
3) Start stopwatch and record the mass of the balance
4) Higher concentration=Faster reaction

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22
Q

What is the method for the Experiment of Sodium Thiosulfate and HCI producing a Cloudy precipitate?

A

1) Add dilute sodium thiosulfate to a conical flask.
2) Put conical flask over paper with a black cross.
3) Add some dilute HCI to flask and start the stopwatch.
4) Watch cross disappear and take time taken
5) Repeat experiment with different concentration
6) The higher concentration, the quicker the reaction and therefore the less time it takes for the cross to disappear.

23
Q

What is a reversible reaction?

A

Is one in which the products of the reaction can react to produce original reactants again( backwards and forwards)

24
Q

Is exothermic reactions negative or positive?

A

Negative

25
Q

Is endothermic reactions negative or positive?

A

Positive

26
Q

What is Equilibrium?

A

Is when the forwards reaction and backwards reaction occur at the same rate in a closed system.

27
Q

What are 3 conditions you could change to equilibrium?

A

1) Change in temperature
2) Pressure
3) Concentration

28
Q

What happens to concentration of reactants when you increase it?

A

When you increase concentration of the reactants the system tries to decrease it by making more products

29
Q

What happens to concentration of the products when you decrease it?

A

When you decrease the concentration of products the system tries to increase it again by reducing the amount of reactants.

30
Q

What happens to Pressure when you increase it?

A

When you increase the pressure, the equilibrium tries to reduce it by moving to the direction where there are fewer molecules of gas

31
Q

What happens to Pressure when you decrease it?

A

When you decrease the pressure, the equilibrium tries to increase it, by moving to the direction where their is more molecules of gas

32
Q

What happens to temperature when you increase it?

A

When you increase temperature,the equilibrium will move in the endothermic direction to try and decrease it meaning more products for the endothermic reaction and fewer of the exothermic reaction,

33
Q

What happens to temperature when you decrease it?

A

When you decrease temperature, the equilibrium will move in the exothermic direction to produce more heat meaning more products for the exothermic reaction, and fewer for the endothermic reaction.

34
Q

What is an exothermic reaction?

A

Process releases heat, causing the temperature of the immediate surroundings to rise.

35
Q

What is an endothermic reaction?

A

Process absorbs heat and cools the surroundings.

36
Q

What is yield?

A

The actual yield is the mass of the useful product made when the reaction is carried out for real.

37
Q

What is Dynamic equilibrium?

A

The concept of dynamic equilibriums is when a reversible reaction is happening both ways at the same time, at the same rate. Because the reaction is happening at the same rate both ways, it does not change.

38
Q

What us the method of working out volume of gas produced in a chemical reaction this is where you react magnesium with hydrocholoric acid?

A

1) Use a measuring cylinder to place 50cm3 of hydrocholoric acid in a conical flask
2) Attach conical flask to a bung and delivery tube
3) Now place delivery tube into a container filled with water.
4) Place a upturned measuring cylinder also filled with water over the delivery tube.
5) Add a 3 cm strip of magnesium to the hydrochloric acid and start stopwatch
6) The reaction produces hydrogen gas which is trapped into measuring cylinder.
7) Every 10 seconds measure the volume of hydrogen gas in the measuring cylinder
8) Continue until no more hydrogen is given off. Repeat experiment using different concentrations of hydrochloric acid.

39
Q

Why do we use gas syringes to measure the volume of gas given off?

A

gives volume accurate to the nearest cm3.

40
Q

The more gas given off during a given time interval means what?

A

The faster the rate of reaction

41
Q

What is the method of finding find how the change in mass affects rate of reaction?

A

1) have a solid in a conical flask
2) add a solution e.g hydrochloric acid
3) the reaction produces bubles producing a gas
4) if gases are aloud to escape threw cotton wool
5) then as reaction progresses the mass on the conical flask decreases because the gas escaping has a mass
6) measure mass at different time intervals

42
Q

On a rate of reaction graph where is the rate of reaction always fastest at?

A

At the start of the reaction meaning gradient is steepest at the start

43
Q

As the reactants start to get used up in a rate of reaction graph what happens to gradient?

A

The slope or gradient become less steap as less reactants avaliable.

44
Q

When the rate of reaction graph is flattened and doesn’t get steep what does this mean?

A

The reaction has stopped because no more product is being produced.

45
Q

On a rate of reaction graph if gradient is at its steepest what does that mean?

A

highest rate of reaction

46
Q

What is a exothermic reaction?

A

It releases heat to surroundings

47
Q

What is a endothermic reaction?

A

Energy is aborbsed by surroundings

48
Q

What does exothermic do to the temperature?

A

it increases temperature

49
Q

What does endothermic do to the temperature?

A

It decreases temperature.

50
Q

When we heat Hydrated copper sulfate what does it form?

A

Anhydrons copper sulphate + water

51
Q

If a reversible reaction is exothermic in one direction what is it in the other?

A

Endothermic

52
Q

2NO2 reacts to form N204 what happens when you increase temperature, the equilibrium is exothermic to the right?

A

If we increase the temperature of the system, then the equilibrium shifts to the left to reduce the temperature, this is because the reverse reaction is endothermic, so energy taken in causing temperature to fall, so the amount of N02 will increase and the amount of N204 will decrease

53
Q

When the product or reactant is a gas what do you measure in?

A

Cm3

54
Q

When the product or reactant is a solid what do you measure in?

A

s