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Chemistry > 2.1.3 Amount of substance > Flashcards

2.1.3 Amount of substance Flashcards

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1
Q

relative atomic mass definition

A

the weighted mean mass of an atom relative to 1/12th the mass of one atom of carbon 12

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2
Q

what form will the compound be if asked to calculate the relative formula mass

A

giant ionic

giant covalent

giant metallic

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3
Q

what form will the compound be if asked to calculate the relative molecular mass

A

simple molecular (covalent)

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4
Q

percentage of an element equation

A

no. of atoms of the element x RAM of element
——————————————————————- X100
relative formula mass of compound

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5
Q

definition of molar mass

A

the mass per mole of a substance in g/mol^-1

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6
Q

amount of substance definition

A

chemists use amount of substance as a means of counting the number of particles in a substance. Its unit is the mole (mol)

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7
Q

give Avogadro’s constant

A

6.02 x 10^23

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8
Q

equation for the number of atoms/ions/molecules

A

moles x Avogadro’s constant

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9
Q

equation for number of moles

A

mass
—————–
molar mass

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10
Q

steps for empirical formula calculation

A
  1. find the mass of each element/ compound
  2. calculate moles of each (do not round till the end)
  3. divide the number of moles by the smallest number to get a ratio
  4. adjust the ratio to make the moles whole numbers
  5. you can then write the empirical formula
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11
Q

definition for water of crystallisation

A

water molecules that are bonded into a crystallisation structure of a compound

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12
Q

definition of hydrated

A

a crystallised compound containing water molecules

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13
Q

word equation of the water of crystallisation of hydrated copper sulphate

A

heat
hydrated copper sulphate (blue) —-> anhydrous copper sulphate (white) + water

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14
Q

symbol equation of the water of crystallisation of hydrated copper sulphate

A

CuSO4 . 5H2O —> CuSO4 . 5H2O

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15
Q

definition of anhydrous

A

contains no waters of crystallisation

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16
Q

method for calculating the amount of water in water of crystallisation

A
  1. weigh crucible
  2. add a known amount of hydrated salt
  3. weigh the crucible and hydrated salt together
  4. heat the hydrated salt strongly for a few minutes
  5. weigh and heat the sample until the mass stays constant
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17
Q

what are the assumptions of the water of crystallisation practical

A
  1. assuming all the water has been lost by heating to constant mass
  2. when heat the salt is not breaking down further into other compounds
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18
Q

molar gas volume definition

A

the volume per mole of gas molecules at the stated temperature and pressure (RTP)

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19
Q

what is the standard room temperature and pressure

A

25 degrees celsius

101KPa pressure

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20
Q

moles with dm3 gas volume equation

A

volume (dm3)
——————-
24

21
Q

moles with cm3 gas volume equation

A

volume cm3
——————
24,000

22
Q

the ideal gas volume equation

A

pressure x vol = mols x ideal gas constant x temperature

23
Q

what is temperature measured in the ideal gas equation

A

Kelvin

24
Q

how do you covert from celsius to kelvin?

A

add 273 to answer

25
Q

how to covert from KPa to Pa

A

times answer by x10^3

26
Q

how to covert answer from cm3 to m3

A

x10^-6

27
Q

how to convert from dm3 to m3

A

x10^-3

28
Q

what is the method for the ideal gas equation calculation question?

A
  1. convert all units
  2. rearrange equation to workout the unknown
29
Q

stoichiometry definition

A

the ratio of the amount in moles of each substance in a chemical reaction

30
Q

steps for stoichiometry calculation

A
  1. state mr for all substances
  2. workout moles for known substance
  3. use ratio to find moles of the unknown
  4. workout the question e.g. vol of gas or mass of substance
31
Q

steps for limiting reactant calculation

A
  1. workout the moles for both reactants
  2. ratio - how much of each reactant you need
  3. identify the limiting reactant
  4. use the limiting reactants mols to workout the rest of the question
32
Q

what is concentration measured in?

A

mol dm^-3

33
Q

moles equation (conc and vol)

A

mols = conc x vol
—————
100

34
Q

what is volume measured in?

A

cm^3

35
Q

what is the equation for concentration?

A

mols x 1000
—————-
volume

36
Q

how do you convert from mol dm^-3 to g dm^-3?

A

times by the Mr

37
Q

what is the equation for percentage yield?

A

actual moles
———————— X100
theoretical moles

38
Q

what is the definition of percentage yield?

A

the amount of product made from the starting materials

39
Q

what are the steps for a percentage yield calculation?

A

1 - workout the Mr of the reactants and products that you have a mass for

2 - workout the actual moles (moles of product)

3 - workout the theoretical moles (moles of the reactant THEN RATIO)

4 - put moles back into equation

40
Q

what is the equation for atom economy?

A

sum of molar masses of desired
——————————————— X100
sum of molar masses of all products

41
Q

what is the atom economy if a reaction only has one product?

A

100%

42
Q

which is the only calculation where you use the big number infront of the element?

A

ATOM ECONOMY

43
Q

how many kg are in a tonne?

A

1000

44
Q

what is the definition for empirical formula?

A

the simplest ratio of atoms of each element in a compound

45
Q

what is the definition of a mole?

A

the amount of any substance containing as many particles as there are carbon atoms in 12g of carbon 12

46
Q

what is the definition of hydrated?

A

a crystallised compound containing water molecules

47
Q

what is the definition of Avogadro’s constant?

A

6.02x10^23 the number of carbon atoms in a mole of carbon 12

48
Q

what is the definition for molecular formula?

A

the actual number of atoms of each element in the compound

Chemistry (6 decks)

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