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operation grade 9 > Chemistry paper 2 > Flashcards

Chemistry paper 2 Flashcards

1
Q

How many electrons are in the outer shell of group 7?

A

7 electrons are in the outer shell for elements in group 7

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2
Q

What happens when you add chlorine water to potassium chloride solution?

A

Nothing will happen

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3
Q

What happens when you add chlorine water to a potassium bromide solution?

A

An orange solution of Br2 forms

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4
Q

What happens when you add chlorine water to a potassium iodide?

A

A brown solution of I2 sill be formed.

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5
Q

what happens when you add bromine water to a potassium chloride solution?

A

Nothing

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6
Q

what happens when you add bromine water to potassium bromide solution?

A

Nothing

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7
Q

what happens when you add bromine water to a potassium iodide solution?

A

A brown solution of I2 is formed

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8
Q

what happens when you add iodine water to potassium chloride?

A

Nothing

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9
Q

what happens when you add iodine water to potassium bromide?

A

Nothing

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10
Q

what happens when you add iodine water to potassium iodide?

A

Nothing

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11
Q

What colour are noble gasses at room temperature?

A

colourless

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12
Q

Why are noble gasses inert? (what does it mean?

A

Because they have a full outer shell of electrons (they don’t react much)

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13
Q

Why is argon used in filament lamps?

A

It isn’t flammable so stops the hot filament from burning away.

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14
Q

What are noble gasses are used to protect metals from being welded together with oxygen and how is this done?

A

Argon and helium are used and they create an inert atmosphere which prevents the oxygen from being welded to the hot metal.

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15
Q

What happens to properties of noble gasses as you go down group 0?

A

The boiling point melting point and density all increase

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16
Q

What are the 3 experiments done to follow reaction rates?

A

Precipitation, change in mass and volume of gas given off.

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17
Q

How does the precipitation practical show how reaction rates work?

A

1)mix 2 reactant solutions and put a flask on a piece of paper that has a mark (like a large cross)
2)look through top of the flask and see how long it takes for the mark to be obscured, faster it disappears the faster the reaction rate.

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18
Q

How does the change in mass show how reaction rates work?

A

1)Can measure the rate of reaction that produces a gas using a mass balance.
2)lost mass can be measured in balance quicker reading drops faster the reaction is

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19
Q

How does the volume of gas given off show how reaction rates work?

A

1) uses gas syringe to measure volume of gas given off.
2)more gas given off during a set time (further back syringe goes) the faster the reaction
3)Reaction finished when no more gas is being produced (bubbles stop)
4)graph should be gas volume against time elapsed
5)use right syringe if too small and rate of reaction to powerful pushes could end out of syringe.

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20
Q

How does surface area affect rate experiment?

A

1)measure volume of gas in syringe, take recordings at set intervals, measure volume of gas produced using syringe readings, repeat the experiment with same concentration and volume of gas. Use same mass of marble chips but change size to bigger and powder.
the sooner the reaction finishes the faster the reaction is, the steeper the gradient graph is the faster the rate of reaction is. Once the line is flat no more gas will be produced. Finer particles = larger surface area. greater mass gives faster reaction and more gas is made due to there being extra surface area

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21
Q

How does changing concentration affect reaction rate?

A

Higher concentration means higher rate of reaction because more particles can collide

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22
Q

What is the practical for reaction rate involving precipitation?

A

Temperature affects reaction rate between HCL and sodium thiosulfate, both are colourless clear acids but when mixed together create a yellow precipitate. The time taken for the precipitate to form measures the rate of reaction. Mix a fixed volume of both, gently heat them before mixing using a water bath, mix them in a conical flask and put that flask over a piece of paper with a black cross. watch the solution go from cloudy to yellow sulfur and measure in seconds how long it takes. the reactions are different at different temperatures, as long as the depth, volume and concentration are kept the same.

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23
Q

What is collision theory?

A

Collision theory is a chemical reactions occur only when the reactant particles collide with sufficient energy to react

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24
Q

Why does increasing temperature increase rate of reaction?

A

Increasing the temperature makes particles have more energy, this means that they have more collisions with other particles and the rate of reaction increases.

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25
Q

why does breaking a solid into more pieces increase its surface area to volume ratio?

A

The solid becomes more exposed an as there are more pieces of the solid there are more pieces for particles to collide and react with

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26
Q

why does increasing concentration or pressure rate?

A

There are more pieces of the solid there are more pieces for particles to collide and react with

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27
Q

Do endothermic reactions absorb or release energy?

A

they absorb energy

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28
Q

How can you measure temperature change?

A

Put a polystyrene cup into a large beaker of cotton wool, add a known volume of a reagant, measure initial temperature, add a mass/volume of your second reagent and stir the reaction mixture, put a lid on the cup to reduce any energy lost by evaporation. record max or minimum temperature as reaction takes place, calculate the temperature change.

29
Q

What does the change in temperature depend on?

A

The type of reagents uses as they can cause and increase or decrease in temperature.

30
Q

What are other types of reactions and explain them?

A

dissolving salts in water as certain salts can make the reaction exothermic - calcium chloride, or endothermic - ammonium chloride.
neutralisation - most are exothermic, is when an acid and base form to make salt and water.
displacement reaction - a more reactive element displaces a less reactive element, normally exothermic.
precipitation reactions - precipitates are insoluble solids which can form from when 2 solutions mix together normally exothermic

31
Q

What happens to bonds during a chemical reaction?

A

Old ones break in order for new ones to form

32
Q

is the energy in endothermic reactions greater to break bonds or is the energy released by forming them greater?

A

energy used is greater

33
Q

is the energy in exothermic reactions greater to break bonds or is the energy released by forming them greater?

A

energy released is greater

34
Q

What is the equation for overall energy change?

A

Energy required to break bonds - energy released by bonds

35
Q

what does it mean if you get a positive energy change and a negative energy change?

A

Positive - endothermic
negative - exothermic

36
Q

What happens to the size of hydrocarbons as you go up the fractional distillation diagram?

A

The hydrocarbons get smaller in size and get used for different reasons or in different vehicles

37
Q

What is the process from crude oil to hydrocarbons?

A

1)formed from plants and animal remains that have been underground for millions of years, crude oil as carbon and hydrogen in it, carbons arrange in chains and rings,, crude oil gets separated into fractions

38
Q

What do the following types of the fuels do these use heating, cars, planes, larger vehicles, ships, roadda?

A

heating - gases
cars - petrol
planes - kerosene
large vehicles - diesel
ships - fuel oil
roads - bitumen

39
Q

What does the size of a hydrocarbon determine?

A

The properties, the shorter the hydrocarbons are mean they can ignite easier, lower boiling points and tend to be gases at room temp, longer ones are usually liquids at room temp and harder to ignite. longer also means they are more viscous.

40
Q

Why do hydrocarbons make great fuels?

A

the combust easily and give out lots of energy when burnt in oxygen

41
Q

how does incomplete combustion occur?

A

It occurs when there is not enough oxygen, products include carbon monoxide. which is dangerous as can stop red blood cells from carrying oxygen and carry carbon monoxide instead

42
Q

What causes acid rain?

A

sulfur dioxide, as when forms with clouds creates sulfuric acid.

43
Q

What are pros and cons of hydrogen as a fuel?

A

pros: very clean, only waste product of water, is renewable and can be obtained from water meaning infinite energy glitch.
cons: special expensive machine is needed, hydrogen needs to be manufactured also expensive uses energy from other sources

44
Q

What is cracking?

A

The splitting up of long hydrocarbons, is a form of thermal decomposition, is done due to higher demand for smaller hydrocarbons.

45
Q

what does cracking use to work?

A

Heat, moderate pressures, catalysts, the vapourised hydrocarbons are passed over a catalyst that is around 400-700 degrees celsius and 70 atm. aluminum oxide is used as the catalyst

46
Q

Why do we use cracking?

A

it helps meet the supply and demand for products like petrol and diesel which lowers the cost as more is available.

47
Q

What was phase 1 of the atmosphere?

A

Volcanoes giving out steam and carbon dioxide, originally molten surface which then cooled to a thin crust, erupting volcanoes spewed out gases from inside earth like carbon dioxide, methane, ammonia, when settled down mainly water vapour and carbon dioxide in atmosphere.

48
Q

What was phase 2 of the atmosphere?

A

green plants evolved and started photosynthesis converting carbon dioxide into oxygen, nitrogen also developed from ammonia reacting with oxygen in atmosphere and released by denitrifying bacteria

49
Q

What was phase 3 of the atmosphere?

A

oxygen build up killed early organisms, but allowed more complex organisms to develop, ozone layer created, and little carbon dioxide now exists

50
Q

what is the make up of gases in atmosphere today?

A

71% nitrogen, 21% oxygen, less than 1% green house gases.

51
Q

How has human activity affected the composition of air?

A

rapid increase in human population, more and more countries become industrialised meaning factories pump it harmful gases, also the uses of diesel and petrol cars release harmful gasses into the atmosphere as population increases so does release of greenhouse gases as more people use petrol and diesel consuming devices, also more landed needed removes plants that can photosynthesis and convert carbon dioxide into oxygen.

52
Q

what are the 6 steps in the greenhouse effect?

A

radiation emitted from the sun, then the earth radiates some heat radiation rest is absorbed, some of this is IR radiation which is absorbed by greenhouse gasses, some of the IR is re-emitted towards earth due to greenhouse gasses, then some is re-emitted to space and finally the absorption and re-emissions is what keeps earth warm.

53
Q

How do increasing greenhouse gases cause climate change?

A

carbon dioxide is increasing and sp is methane which is released by livestock, more livestock farmed more methane produced, this is an issue as it is a super effective greenhouse meaning warms up earth quicker, this has caused the earth’s temperature to rise, hence why it is called global warming, which is a form of climate change,

54
Q

what is more accurate historical data or current records?

A

Current records are much more accurate

55
Q

why is current records more accurate than hsitorical?

A

current global temps and carbon dioxide levels can be worked out accurately as based on worldwide measurements that have been taken, historical is less accurate as going back far enough shows there is no global warming or levels of greenhouse gases,

56
Q

what are ways we can estimate carbon dioxide levels in the past?

A

Ice cores(have bubbles trapped inside, tree rings, fossils)

57
Q

How can we slow down climate change?

A

cut down the amount of greenhouses gasses we are releasing, we can do this by using less fossil fuels like cycling and walking instead of driving, use renewable energy instead of un-renewable and use energy efficient technology

58
Q

What do we use flame tests for?

A

identify metal ions

59
Q

What colour flames do the following ions give:
Lithium, Sodium, Potassium, Calcium, Copper?

A

Lithium: red, sodium: yellow, potassium:lilac, calcium:orange red and copper is a blue green flame.

60
Q

If you can not identify a metal ion with a flame what can you used instead?

A

A coloured precipitate using NaOH

61
Q

What colour precipitate do the following give: Aluminium, calcium, copper, iron II and iron III

A

Aluminium white the colourless, calcium: white, copper:blue, iron II:green and iron III:brown

62
Q

How can you test for ammonia?

A

Ammonia created when NaOH is added to Ammonium Ions. you can test by using damp red litmus paper near the suspected area and it will turn from red to blue.

63
Q

How can you test for halide ions?

A

a silver nitrate solution

64
Q

what precipitate do you get from silver chloride in the following: chloride, bromide, iodide

A

Chloride:white, bromide:cream, iodide:yellow

65
Q

How do you test for sulfate ions and how do you test for carbonates?

A

For sulfate ions use a barium chloride solution a white precipitate will form, for carbonates use a dilute acid fizzing will occur if there are carbonates

66
Q

What type of method is flame photometry and what do we use it for?

A

it is instrumental method that allows us to identify the ions in a dilute solution, each ion produces its own line spectrum, wavelength intensity shows concentration.

67
Q

What is the difference between alkene and alkane bonds?

A

alkene have double bonds

68
Q

How can you test for an alkene?

A

put in bromine water as when shaken it will decolourise the bromine water and it will go from an orange colour to colourless as bromine as added across the double bond.

operation grade 9 (13 decks)

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