Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chemistry > paper 2 advanced information > Flashcards

paper 2 advanced information Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

what is the rate of a chemical reaction?

A

how fast the reactants are changed into products

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what are two examples of chemical reactions with slow rates?

A

iron rusting and chemical weathering (like acid rain damage to limestone buildings)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is an example of a moderate speed reaction?

A

magnesium reacting with an acid to form a gentle stream of bubbles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are two examples of fast reactions?

A

burning and explosions (but explosions are faster)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what are two ways you can find the speed of a reaction?

A

recording the amount of product formed, or recording the amount of reactant used up, over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

on a rate of reaction graph, does a steeper line mean a faster or slower reaction?

A

faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

why does the line become less steep over time on a rate of reaction graph?

A

as the reactants are used up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what must happen in order for a reaction to occur?

A

particles must collide with enough energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what two things does the rate of a chemical reaction depend on?

A
  1. the collision frequency

2. the energy transferred during a collision

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what are four things the rate of reaction depends on?

A
  1. temperature
  2. the concentration of a solution or the pressure of a gas
  3. surface area
  4. the presence of a catalyst
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what effect does changing temperature have on the rate of a reaction?

A

in order for a reaction to occur, the particles have to collide. increasing the temperature increases the speed the particles move at, and so they collide more frequently, so an increase in temperature increases the rate of a reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what effect does concentration have on rate of reaction?

A

in order for a reaction to occur, particles have to collide. the more concentrated a solution is, the more particles there are per unit volume, so there are more frequent collisions. this means that an increase in concentration increases the rate of a reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what effect does pressure have on the rate of a reaction?

A

in order for a reaction to take place, particles must collide. the higher the pressure, the more particles there are per unit volume, so there are more frequent collisions. this means that an increase in pressure increases the rate of reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what effect does surface area have on the rate of a reaction?

A

in order for a reaction to occur, particles have to collide. increasing the surface area to volume ratio of a solid will increase the amount of the solid exposed to the other reactants, so more frequent collisions will occur. this means that an increase in surface area to volume ratio increases the rate of a reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is a catalyst?

A

a substance that speeds up the rate of a reaction, without being used up in the reaction itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

are catalysts part of the overall reaction equation?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how do catalysts work?

A

by decreasing the activation energy needed for the reaction to occur. they do this by providing an alternative reaction pathway with a lower activation energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

give an example of a biological catalyst

A

enzymes - they catalyse reactions in living things

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the formula for the mean rate of reaction?

A

rate of reaction = amount of reactant used or amount of product formed / time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

how do you find the rate of a reaction at one particular point in time?

A

you have to plot a graph and find the gradient at that time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

what are the three ways to measure the rate of a reaction?

A
  1. precipitation and colour change
  2. change in mass (usually gas given off)
  3. the volume of gas given off
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what units would you use to measure a product or reactant if it’s a gas?

A

cm^3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what units would you use to measure a product or reactant if it’s a solid?

A

grams

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is the most common measurement of time when calculating rate of reaction?

A

seconds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what are common examples of the units used for the rate of a reaction

A

cm^3/s, g/s, or mol/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

how do you measure the rate of a reaction using precipitation and colour change? (4 points)

A
  1. you can record the visual change in a reaction if the initial solution is transparent and the product is a precipitate which clouds the solution (it becomes opaque)
  2. you can observe a mark through the solution and measure how long it takes for it to disappear - the faster the mark disappears, the quicker the reaction
  3. if the reactants are coloured and the products are colourless (or vice versa), you can time how long it takes for the solution to lose (or gain) its colour
  4. the results are very subjective - different people might not agree over the exact point when the mark ‘disappears’ or the solution changes colour. Also, if you use this method, you can’t plot a rate of reaction graph from the results
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

how do you measure the rate of a reaction using a change in mass? (5 steps)

A
  1. measuring the speed of a reaction that produces a gas can be carried out using a mass balance
  2. as the gas is released, the mass disappearing is measured on the balance
  3. the quicker the reading on the balance drops, the faster the reaction
  4. if you take measurements at regular intervals, you can plot a rate of reaction graph and find the rate quite easily
  5. this is the most accurate of the three methods because the mass balance is very accurate, but it has the disadvantage of releasing gas straight into the room
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

how do you measure the rate of a reaction using the volume of gas given off?

A
  1. this involves the use of a gas syringe to measure the volume of gas given off
  2. the more gas given off during a given time interval, the faster the reaction
  3. gas syringes usually give volumes accurate to the nearest cm^3, so they’re quite accurate. you can take measurements at regular intervals and plot a rate of reaction graph using this method too. you have to be quite careful though - if the reaction is too vigorous, you can easily blow the plunger out of the end of the syringe
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what do magnesium and HCl react to produce?

A

Hydrogen gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

what are the 6 steps to using the reaction between magnesium and HCl to investigate the effect of concentration on the rate of reaction?

A
  1. start by adding a set volume of dilute hydrochloric acid to a conical flask and carefully place on a mass balance
  2. now add some magnesium ribbon to the acid and quickly plug the flask with cotton wool
  3. start the stopwatch and record the mass on the balance. take readings of the mass at regular intervals
  4. plot the results in a table and work out the mass lost for each reading. now you can plot a graph with time on the x-axis and loss of mass on the y-axis
  5. repeat with more concentrated acid solutions. variables such as the amount of magnesium ribbon and the volume of acid used should be kept the same each time - only change the acid’s concentration. This is to make your experiment a fair test
  6. the three graphs show that a higher concentration of acid gives a faster rate of reaction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

what are the 6 steps to using the reaction between sodium thiosulfate and HCl to investigate the effect of concentration on the rate of reaction?

A
  1. Sodium Thiosulfate and HCl are both clear solutions. They react together to form a yellow precipitate of sulfur
  2. start by adding a set volume of dilute sodium thiosulfate to a conical flask
  3. place the flask on a piece of paper with a black cross drawn on it. add some dilute HCl to the flask and start the stopwatch.
  4. now watch the black cross disappear through the cloudy sulfur and time how long it takes to fully disappear
  5. the reaction can be repeated with solutions of either reactant at different concentrations (but only change the concentration of one reactant at a time). the depth of the liquid must be kept the same each time
  6. The higher the concentration, the quicker the reaction and therefore the less time it takes for the mark to disappear
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

why should the reaction between sodium thiosulfate and HCl be carried out in a well-ventilated place?

A

because it releases sulfur dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

what do sodium thiosulfate and HCl react together to produce?

A

sulfur - a yellow, cloudy precipitate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

what does a rate of reaction graph show on its X and Y axis?

A

it shows the amount of product formed or reactant used up on the y-axis and time on the x-axis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

how do you find the mean rate for a whole reaction?

A

you work out the overall change in the y-axis of the graph (amount of product formed or reactant used up), and divide this by the total time taken for the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

how do you use a graph to find the rate of a reaction at a particular point in time?

A

you draw a tangent and work out the gradient of the tangent:

  1. position a ruler on the graph at the point where you want to know the rate
  2. adjust the ruler until the space between the ruler and the curve is equal on both sides of the point
  3. draw a line along the ruler to make the tangent. extend the line right across the graph
  4. pick to points on the line that are easy to read. use them to calculate the gradient of the tangent in order to find the rate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

how does a reversible reaction reach equilibrium?

A
  1. as the reactants react, their concentrations fall, so the forward reaction will slow down. But as more and more products are made and their concentrations rise, the backward reaction will speed up
  2. after a while the forward reaction will be going at exactly the same rate as the backward one - the system is at equilibrium
  3. at equilibrium, both reactions are still happening, but there’s no overall effect (it’s a dynamic equilibrium). This means the concentrations of reactants and products have reached a balance and won’t change
  4. equilibrium is only reached in a closed system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

can a reaction be at equilibrium with unequal amounts of reactants and products?

A

yes - equilibrium doesn’t mean that the amounts of reactants and products are equal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

what does it mean if the position of equilibrium lies to the right?

A

the concentration of the products is greater than that of the reactants

40
Q

what does it mean if the position of equilibrium lies to the left?

A

the concentration of reactants is greater than that of the products

41
Q

what conditions does the position of equilibrium depend on?

A
  1. the temperature
  2. the pressure (in gases)
  3. the concentration of the reactants and products
42
Q

is the reaction from hydrated copper sulfate to anhydrous copper sulfate + water endothermic or exothermic?

A

endothermic

43
Q

is the reaction from anhydrous copper sulfate + water to hydrated copper sulfate endothermic or exothermic?

A

exothermic

44
Q

what is le chatalier’s principle?

A

the idea that if you change the conditions of a reversible reaction at equilibrium, the system will react to counteract that change

45
Q

what can le chatalier’s principle be used for?

A

it can be used to predict the effect of any changes you make to a reaction system

46
Q

what happens if you lower the temperature of a reversible reaction at equilibrium?

A

the equilibrium will move in the exothermic direction to produce more heat. this means you’ll get more products for the exothermic reaction and fewer products for the endothermic reaction

47
Q

what happens if you raise the temperature of a reversible reaction at equilibrium?

A

the equilibrium will move in the endothermic direction to try and decrease the temperature. You’ll get more products for the endothermic reaction and fewer products for the exothermic reaction

48
Q

which reactions at equilibrium are affected by pressure?

A

those involving gases

49
Q

what happens if you increase the pressure of a reversible reaction at equilibrium?

A

the position of equilibrium shifts towards the side where there are fewer molecules of gas - it tries to reduce the pressure

50
Q

what happens if you decrease the pressure of a system at equilibrium?

A

the position of equilibrium shifts towards the side where there are more molecules of gas in an attempt to increase the pressure again

51
Q

what happens if you change the concentration of either the reactants or the products of a system at equilibrium?

A

the system will no longer be at equilibrium, so it responds to bring itself back to equilibrium

52
Q

what happens if you increase the concentration of the reactants in a system at equilibrium?

A

the system makes more products to counteract the change

53
Q

what happens if you decrease the concentration of products in a system at equilibrium?

A

the system reduces the amount of reactants to counteract the change

54
Q

what is a hydrocarbon?

A

any compound that is formed from carbon and hydrogen atoms only

55
Q

what is the general formula for alkanes?

A

CnH2n+2,

56
Q

what are alkanes?

A

a homologous series of saturated hydrocarbons

57
Q

what is a homologous series?

A

a group of organic compounds that react in a similar way

58
Q

what are the first four alkanes?

A

methane, ethane, propane, butane

59
Q

what is a displayed formula?

A

a drawing showing all the atoms and bonds in a molecule

60
Q

what is the formula for methane?

A

CH4

61
Q

what is the formula for Ethane?

A

C2H6

62
Q

what is the formula for propane?

A

C3H8

63
Q

what is the formula for Butane?

A

C4H10

64
Q

what are the properties of shorter hydrocarbons?

A
  • less viscous
  • more volatile (lower boiling points)
  • more flammable
65
Q

what are the properties of longer hydrocarbons?

A
  • more viscous
  • less volatile (higher boiling points)
  • less flammable
66
Q

what are short-chain hydrocarbons used for? why?

A

they are used as ‘bottled gases’ - stored under pressure as liquids in bottles - because of their low boiling points

67
Q

what is the equation for the complete combustion of a hydrocarbon?

A

hydrocarbon + oxygen -> carbon dioxide + water

68
Q

during the combustion of a hydrocarbon, what happens to the carbon and hydrogen?

A

they are both oxidised

69
Q

why are hydrocarbons used as fuels?

A

they release a lot of energy when they combust completely

70
Q

write a balanced symbol equation for the complete combustion of methane

A

CH4 + 2O2 -> CO2 + 2H20

71
Q

write a balanced symbol equation for the complete combustion of propane

A

C3H8 + 5O2 -> 3CO2 + 4H2O

72
Q

how is crude oil made?

A

from the remains of an ancient biomass, made up mainly of plankton, that’s been buried in mud

73
Q

what type of fuel is crude oil?

A

a fossil fuel

74
Q

is crude oil renewable?

A

no

75
Q

what does crude oil consist of?

A

different lengths of hydrocarbons and a bit of sulfur

76
Q

what are the 4 steps to separating hydrocarbons by fractional distillation?

A
  1. the oil is heated until most of it has turned into gas. The gasses enter a fractionating column, and everything that remains liquid is drained off
  2. in the fractionating column there’s a temperature gradient (it’s hot at the bottom and cooler as you go up
  3. the longer hydrocarbons have high boiling points. They condense back into liquids early on, when they’re near the bottom. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near to the top of the column where it’s cooler.
  4. you end up with the crude oil mixture separated out into different fractions. Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
77
Q

what fuels are obtained from the fractional distillation of crude oil, in order from the highest boiling point (collected at the bottom) to the lowest boiling point (collected at the top)

A

bitumen, heavy fuel oil, diesel oil, kerosene, petrol, LPG (liquefied petroleum gas)

78
Q

which two hydrocarbons does LPG mostly contain?

A

propane and butane

79
Q

what are the three oils that count as heavy fuel oil?

A

heating oil, fuel oil, lubricating oil

80
Q

what are the two main uses of crude oil?

A
  1. oil provides the fuel for most modern transport. Diesel oil, kerosene, heavy fuel oil and LPG (liquid petroleum gas) all come from crude oil
  2. the petrochemical industry uses some of the hydrocarbons from crude oil as a feedstock to make new compounds for use in things like polymers, solvents, lubricants and detergents
81
Q

what are organic compounds?

A

compounds containing carbon atoms

82
Q

what is cracking?

A

splitting up long-chain hydrocarbons

83
Q

why do we use cracking?

A

short-chain hydrocarbons are flammable so make good fuels and are in high demand. However, long-chain hydrocarbons form thick gloopy liquids like tar which aren’t very useful, so we use cracking to turn a lot of the longer alkane molecules produced from fractional distillation into smaller, more useful ones.

84
Q

what are some of the products of cracking useful as?

A

fuels, e.g. petrol for cars and paraffin for jet fuel

85
Q

what does cracking produce other than alkanes?

A

alkenes

86
Q

which are more reactive: alkanes or alkenes?

A

alkenes

87
Q

what are alkenes used for?

A

they’re used as a starting material when making lots of other compounds and can be used to make polymers

88
Q

what is the test for alkenes?

A

bromine water - when in the presence of an alkene it turns from bright orange to colourless

89
Q

what type of reaction is cracking?

A

a thermal decomposition reaction - it breaks molecules down by heating them

90
Q

what are the two methods of cracking?

A
  1. catalytic cracking

2. steam cracking

91
Q

what are the 3 steps to catalytic cracking?

A
  1. you heat and vaporise long-chain hydrocarbons
  2. then the vapour is passed over a hot powdered aluminium oxide catalyst
  3. the long-chain molecules split apart on the surface of the specks of catalyst
92
Q

how do you perform steam cracking?

A

vaporise long-chain hydrocarbons, mix them with steam and then heat them to a very high temperature

93
Q

what is the word equation for cracking?

A

long-chain hydrocarbon molecule -> shorter alkane molecule + alkene

94
Q

how do you balance a chemical equation for cracking?

A

make sure that there is the same number of carbon molecules on both sides

95
Q

what is the general formula for alkenes?

A

CnH2n

Chemistry (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions