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CHEMISTRY > Quantitative chemistry > Flashcards

Quantitative chemistry Flashcards

1
Q

what is concentration

A

measurement of how many moles of a substance is dissolved in a solvent it is measured in moles per dm3

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2
Q

what is the equation for moles involving mass and Mr

A

moles = mass divided by mr

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3
Q

what is the equation for concentration involving moles and volume

A

concentration = moles divided by volume

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4
Q

what is a titration

A

where an acid reacts with an alkali to give us salt and water

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5
Q

what is an ionic equation

A

H+ +OH- -> H20 (neutrilization)

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6
Q

what equipment do you need to perform a titration

A

buretter(unknown concetration
pipette(known concentration)
concial flask
stand

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7
Q

what is step one of performing a titration

A

use pipette to take 25 cm of the known concentration substance

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8
Q

what is step 2 of performing a titrationn

A

add an indiator to the conical flask which is phentel phalene

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9
Q

what is an indicator

A

substance that changes colour in an acid or alkali

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10
Q

what is yield

A

the mass of the product tjat is made in a chemical reaction

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11
Q

what is the equation for percentage yield

A

actual yield / theortical yield x 100

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12
Q

what are some reasons why we cant have 100% yield

A

1.some products will be left behind
2. not all rectants completely react for example in a resible reaction ]
3. sometimes unexpectant [products will happen as a side reaction
4.some product will be lost in separating
5.some of the reactant will not be pure

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13
Q

what is atom economy

A

the proportion of atoms in the reactants that are covered into useful products reactants with one product will have 100% atom economy

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14
Q

what is the equation for atom economy

A

rfm of desired products / rfm of all reactants x 100

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15
Q

what is the equation for gas volume including moles and volume

A

moles = volume / 24 dm 3

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16
Q

what are the conditions of the haber process

A

iron cataylst,hydrogen and nitrogen

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17
Q

what are the components of air

A

79% nitrogen , 20% oxygen,0.04% carbpn dioxide and less than 1% of noble gasses - argon,neon

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18
Q

How does the Haber process work

A
  1. the two gases,nitrogen and hydrogen will go to the compressor where they will be compressed together
  2. the compressor is at 200 atmosphere pressure and the tempreturew is 450 degrees
  3. the combined nitrogen and hydrogen will then go into the reaction vessel
  4. Iron catalyst will speed up the reaction then it will go into the cooling chamber
  5. the cooling chamber is where the ammonia will condense into liquid ammonia and any unreacted hydrogen and nitrogen will recycled. The ammonia will be collected for fertiliser
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19
Q

where does nitrogen come from

A

air

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20
Q

where does hydrogen come from

A

methane(natural gas

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21
Q

what is a reversible reaction

A

a reaction in which the product cam also combine to form the reactants

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22
Q

what is equilibrium

A

the rate at which the foward reaction = the rate of the backward reaction

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23
Q

why can you reach equillirbum in a reversible reaction

A

you can go both ways,both backward and forward

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24
Q

what is le chatelier’s principle

A

if a system is at equillibrium and a change is made to any conditions, then the susyem responds to contract the change

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25
Q

where can equillbrium only happen

A

in an open or closed system where by you are not adding or removing anything from the reaction

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26
Q

what are three factors that effect equllibrium

A

temperature,concentration and pressure

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27
Q

how does concentration effect equllibrium

A
  1. add more reactants mean an increase in concentration of the reactants and causes equilibrium to shift to the right because you have more reactants so they will combine to make products.So the forward reaction will be favoured and you will get more products produced until you reach equilibrium again
  2. less reactants, equilibrium will shift to the left so the products will combine to make more reactants
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28
Q

how does temperature effect equilibrium

A
  1. in every reversible reaction , if one side is exothermic, the opposite side will be endothermic
  2. expthermic releases energy to the surrounding
    3.endothermic takes in energy from the surroundings
  3. the energy is mostly heat energy or thermal
  4. increase the temperature endothermic will be favoured and would favour the backward reaction,equilibrium will shift to the left
    6.decrease in temperature ,exothermic reaction and will favour forward reaction,more product formed
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29
Q

how does pressure effect equillibrium

A
  1. always look at the number of moles
    222, when you increase the pressure, it will favour the side with more moles,equilibrium will shift to right, reactants will combine to get products,wants more products,favor forwards reaction until you reach equilibrium again
  2. pressure only applies yo gasses because tey are the ones you can compress
30
Q

what effect does pressure have on the yield of ammonia

A

causes higher yield of ammonia

31
Q

what effect does pressure have the rate of reaction

A

higher/faster rate of reaction

32
Q

what pressure conditions are used to make a higher yield of ammonia and rate of reaction

A

high pressure,200 not too high, perfect to increase the yield and rate of reaction

33
Q

what effect does temperature have on the yield of ammonia

A

decrease on the yielf of ammonai

34
Q

what effect does tempreature have on the rate of reaction

A

higher/faster rate of reaction

35
Q

what tempreature conditions are used to make a low yield of ammonia and high rate of reaction

A

medium tempreature

36
Q

what effect does cataylst have on thhe yielf of ammonia

A

no effect

37
Q

what effect does catylst have on the rate of reaction

A

higher/faster rate of reaction

38
Q

what cataylst conditions are used to make a high rate of reaction

A

increase rate no effect on yield

39
Q

what effect does removing ammonia from the reaction have on the yield of ammonia

A

higher effect on yielf of amonia

40
Q

what effect does removing ammonia from the reaction have on the rate of reaction

A

no effect

41
Q

what removing ammonia from the reaction conditions are used to make a higher yield of ammonia

A

equilibrium will shift to the right because of the increase of yield

42
Q

what is dynamic equillibrium

A

the rate of the foward reaction = to the rate of the backward reaction and it happens at thee same time

43
Q

what is fertilliser

A

a chemical or natural sibstance added to soil or land to improve the growth of plants

44
Q

nitrogen in the air must be what

A

fixed into solule nitrates (NO3)

45
Q

how do you make ammonium nitrate

A

ammonia + nitric acid

46
Q

how do you make ammonium phosphate

A

ammonia + phosphoric acid

47
Q

how do you make ammonium sulfate

A

ammonia +sulfric acid

48
Q

why do plants need nitrogen

A

for healthy growth

49
Q

what will happen if we leave the nitrogen in the air

A

we wont have any nitrate because we are eating the plants

50
Q

what is nitrogen used for

A

to make the plants green

51
Q

what is phosphorus used for

A

strong roots

52
Q

what is potassium used for

A

healthy growth

53
Q

what is a battery called

A

a cell

54
Q

what are 2 or more cells called

A

battery

55
Q

what do cells transfers

A

chemical energy to elecctrical energy and we can use that to power gadgets

56
Q

what is electricty

A

the flow of electrons (current)

57
Q

how do you create the flow of electrons

A

you beed two metals,one metal that is more reactive than the other,one less reactie than the other and the salt solution because you want to make ions which allows electricity to be conducted

58
Q

what are simple chemical cells

A

involves two metals,one more reactive than the other

59
Q

what does the production of voltage depend on

A

the type of electrodies and electrolytes

60
Q

greater the diffrence in reactivity will ……

A

greater diffrence in reactiveity will produce greater voltage

61
Q

what will the battery carry

A

chemical reactoon

62
Q

what are the two types of batteries

A

non rechargable and rechargable

63
Q

how does the inside of a battery work

A
  1. the more reacrive the metal is the more oxidised
  2. the less reactive metal is the more reduced
  3. in a battery the electrodes are carbon rod and zin casting and carbon will displace zinc
    4.ammonium chloride is the electrolyte paste because it is liquid enough to conduct electricity and not liquid enough to fall out the battery
64
Q

what is a non rechargable battery

A

ince the reactants are used up the chemical reaction stops for example alkaline batteries

65
Q

what is a rechargable battery

A

reactions can be revseed by a suooky with a current and can be used multiple times for example cadiumum batteries

66
Q

what are fuel cells

A
  • use hydrogen and oxygen
  • doesn’t need recharging
  • constant supply of fuel
  • fuel must be supplied constantly
67
Q

how do fuel cells work

A
  1. in the middle are electrolystes and separate electrodes made of graphite
    2.hydrogen is supplied to the negative electrode and the gas will diffuse through the graphite electrode
    3.when it diffuses it is going to be reacted with hydroxide Ions to form water#
    4.and there will be elections produced and will go to positive electrode where oxygen will gain electrox to form dioxide ions
    5.oxygen is supplied to positive electrode and diffuse through graphite electrode and that’s where it will gain that electrons to from the hydroxide ion
68
Q

what is the half equation for hudrgen at the negative electrode

A

H2 +2OH- -> 2H20 +2e-

69
Q

what is the half equation for oxygen at the positive electrode

A

O2 +2H20 + 4e - -> 4OH

70
Q

what are three advantages for hydrogen as fuel

A
  • only waste product is water(pollutant)
  • fuel cells can be any size for a range of uses
  • don;t need to be recharged using electricity
71
Q

what are three disadvantages for hydrogen as fuel

A
  • hydrogen gas is highly flammable(potinetially toxic )#
  • difficult to store/compress
  • hydrogen is sometimes produced from ono rechargeable batteries

CHEMISTRY (16 decks)

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