Summer Assessment 3- more Flashcards

1
Q

how can you work out the speed of a reaction on a graph

A
  • by recording the amount of product formed or the amount of reactant used up over time
  • the steeper the line on a graph the fatser the reaction
  • line becomes less steep as reactants are used up
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2
Q

what do the quickest reactions show on a graph

A

-they have the steepest line and become flat in the least time

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3
Q

what does the rate of a chemical reaction depend on

A
  • collision frequency of reacting particles- the more collisions the faster the reaction
  • energy transferred during a collision
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4
Q

what is activation energy

A

-the minimum amount of energy particles need to react

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5
Q

why to particles need activation energy

A

-to break the bonds in reactants to start to the reaction

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6
Q

explain the method you would carry out to measure how surface area affects rate

A
  • use marble chips and HCL
  • set up the apparatus so you have a conical flask with marble chips in it as well as HCL- attach to the bung in the conical flask a gas syringe
  • measure volume of gas produced using a gas syringe
  • take readings at regular intervals and record the results
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7
Q

why does using finer particles of solid mean a higher rate of reaction

A

-as finer particles mean the marble has a larger surface area

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8
Q

what effect does changing the concentration of acid have on the rate of reaction

A

a higher concentration gives a faster reaction

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9
Q

what is the general formula for alkenes

A

CnH2n

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10
Q

what is the empirical formula (for ethene)

A

CH2

-simplest ratio of atoms

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11
Q

what is the molecular formula (for ethene)

A

C2H4

-actual number of atoms of each element in a molecule

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12
Q

what is the structural formula (for ethene)

A

CH2CH2

-shows arrangement of atoms carbon by carbon

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13
Q

what is a homologous series

A

-a group of compounds that can all be represented by the same general formula

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14
Q

what is a functional group

A
  • a group of atoms that determine how a compound typically reacts
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15
Q

definition of isomer

A

two or more molecules with the same molecular formulae but different structural formula

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16
Q

what can you infer from differently shaped carbon chains

A
  • these isomers have similar chemical properties

- but different physical properties due to the change in shape of the molecules

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17
Q

what could you infer from functional groups being in different places

A

-these isomers have different physical properties

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18
Q

what could you infer from functional groups being different

A

-these isomers have different physical and chemical properties

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19
Q

What is a hydrocarbon?

A

a compound of hydrogen and carbon only

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20
Q

What happens when you burn a fuel?

A

releases energy in form of heat

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21
Q

What is burning a fuel also known as?

A

-combustion reaction

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22
Q

Why do hydrocarbons make great fuels?

A

as the combustion reaction that happens when you burn them in oxygen gives out lots of energy

23
Q

hydrocarbon + oxygen =

A

carbon dioxide + water

24
Q

What is complete combustion

A

-when you burn hydrocarbons in plenty of oxygen, the only products are CO2 and water

25
Q

What type of reaction is hydrogen + oxygen?

A

complete combustion

26
Q

What does incomplete combustion produce?

A

carbon monoxide + soot + carbon

27
Q

When does incomplete combustion occur?

A

when there is not enough oxygen around

28
Q

How is carbon monoxide is poisonous?

A
  • It combines to red blood cells and stops blood doing proper job of carrying oxygen round the body
  • lack of oxygen in blood supply can result in death
29
Q

What is acid rain caused by?

A
  • sulfur dioxide

- nitrogen oxides

30
Q

When may sulfur dioxide and nitrogen oxides be produced?

A

when fractions from crude oils are burned

31
Q

Where does sulfur dioxide come from?

A

comes from sulfur impurities in hydrocarbon fuel

32
Q

How are nitrogen oxides formed?

A
  • when temp is high enough for nitrogen and oxygen react in the air
  • this often happens in car engines
33
Q

What is made when sulfur dioxide and nitrogen oxides mix with water vapour in the clouds?

A
  • dilute sulfuric acid and nitric acid

- the rain that then falls from these clouds is known as acid rain

34
Q

Why is acid rain an issue?

A
  • causes lakes to become acidic

- many plants and animals die as a result

35
Q

What are alkanes?

A
  • saturated hydrocarbons
  • they are chains of carbon atoms surrounded by hydrogen atoms
  • single bonds between carbon atoms
36
Q

What is the general formula for alkanes?

A

CnH2n+2

37
Q

What are the names of the first five alkanes?

A
methane
ethane
propane
butane
pentane
38
Q

What do alkanes burn in?

A

complete combustion reactions

39
Q

Write the word equation for the burning of propane

A

propane + oxygen -> carbon dioxide + water

40
Q

What do alkanes react with and what is this called?

A

alkanes react with halogens to form haloalkanes

41
Q

What type of light is needed to make a haloalkane?

A

ultraviolet light

42
Q

What type of reaction is a haloalkane made in?

A

substitution reaction

43
Q

What is a substitution reaction?

A

hydrogen atom from alkane is substituted with chlorine or bromine

44
Q

Write the word equation for the reaction of bromine with an alkane (methane)

A

methane + bromine -> bromomethane + hydrogen bromide

45
Q

What are addition polymers made from?

A

-unsaturated monomers

46
Q

How is an addition polymer formed?

A

by joining up many small molecules called

monomers

47
Q

What are polymers?

A

A large molecule made when many small molecules (monomers) join together. Consists of many repeat units.

48
Q

What is addition polymerisation

A

When lots of unsaturated monomer molecules open up their carbon-carbon double bonds and join together to form polymer chains

49
Q

What are Monomers?

A

Molecules which can join up to form a polymer.

50
Q

What does ethene become in addition polymerisation?

-how does its displayed formula change

A

poly(ethene)- (c2H4)n

ethene displayed formula:
H H
\ /
C = C
/ \
H H

—> pressure and a catalyst

H H H H H H
-C-C-C-C-C-C-
H H H H H H
poly(ethene)

51
Q

What does propene become in addition polymerisation?

-how does its displayed formula change

A

poly(propene)- (C3H6)n

propene displayed formula:
H H
\ /
C = C
/ \
H CH3

—> pressure and a catalyst

H H
(-C-C-) n
H CH3

poly(propene)

52
Q

Why is it diffiuclt to get rid of addition polymers

A
  • as most addition polymers are inert - they don’t react easily
  • as the carbon-carbon bonds in the polymer are very strong and aren’t easily broken
  • this means it takes a v long time for addition polymers to biodegrade
  • the burning of plastics also release toxic gases, so you can’t get rid of addition polymers that way
53
Q

Name 2 ways why polymers are hard to get rid of

A
  • it takes a long time for addition polymers to biodegrade

- you can’t burn them either as that releases toxic gases

54
Q

What is condensation polymerisation

A

Polymerisation of monomers in which each time two monomers combine, a small molecule such as water or hydrogen chloride is removed (e.g. a dicarboxylic acid and a diol).