Amount of substance Flashcards

1
Q

what is 1000kg in tonnes?

A

1 tonne

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2
Q

what is 1,000,000 g in tonnes?

A

1 tonne

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3
Q

what is 1000mg in grams?

A

1g

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4
Q

what is 1000 dm3 in m3?

A

1m3

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5
Q

what is 1,000,000 cm3 in m3?

A

1m3

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6
Q

what is 1000 cm3 in dm3?

A

1 dm3

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7
Q

what is 1 dm3 in m3?

A

1 x 10-3m3

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8
Q

What is 1cm3 in m3?

A

1 x 10-6m3

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9
Q

what is 1KPA in Pa?

A

1000pa

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10
Q

how do you convert Celsius to K?

A

°C + 273

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11
Q

what is the mole defined as?

A

The amount of substance that contains 6.02 x 10 23 particles (example of these can be atoms or ions or molecules)

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12
Q

what is the meaning of avogrado’s constant?

A

The number of particles in each mole of carbon-12

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13
Q

What is the equation? For avogrado’s constant?

A

n.o of particles = n x avogrado’s constant

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14
Q

what is molar mass?

A

the mass (in g) of 1 mole of substance. it had the units of gmol-1

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15
Q

What are the two terms of molar mass?

A

Relative molecular mass and relative formula mass

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16
Q

why are there two terms of molar mass?

A

Some compounds exist as simple, covalent molecules(like CO2) and other compounds are giant ionic crystalline structures (eg NaCl)

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17
Q

How do you find the percentage by mass of an element in a compound?

A

Divide the relative mass of the atoms of the element in the compound by the total mass of the compound (Mr) and then multiplied by 100

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18
Q

how do you find the moles elements?

A

mass (g)/relative atomic mass

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19
Q

how do you find the moles for simple molecules?

A

mass/relative molecular mass

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20
Q

how do you find the moles for ionic compounds?

A

mass/ relative formula mass

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21
Q

what is the a molecular formula?

A

The actual number of atoms in each element of the compound

22
Q

what are the steps of calculating the empirical formula for percentage composition?

A

-Divide by Ar
-Divide by smallest

23
Q

how do you calculate the empirical formula for the percentage of one reactant if the percentage of only one element is give?

A

subtract this number from 100 to find a percentage of the element, then complete the calculation as normal

24
Q

How do you calculate the empirical formula from composition by mass of all atoms present?

A

if the mass of each element is given, these can be converted into moles and then ratio deduced

25
Q

what are the stoichiometric numbers?

A

The big numbers in front of the formulae or symbols

26
Q

What is the definition of molar gas volume?

A

The volume per mole of gas molecules at a state of temperature and pressure (normally room temperature and pressure)

27
Q

what volume does one mole of gas have at room temperature?

A

24.0dm3mol-1

28
Q

what is the equation for volume when it is dm3?

A

n=v/24

29
Q

what is the equation for volume when it is in cm3?

A

n=v/24000

30
Q

what does R stand for?

A

gas constant (8.314 jmol-1 k-1)

31
Q

What is room pressure?

A

101 KPa

32
Q

what is the unit of v in pV=nRT

A

m3

33
Q

what is the second gas equation?

A

P1 V1/ T1=P2 V2/ T2

34
Q

what is the equation for volume when V is in dm3?

A

n=cV

35
Q

how do you get from gdm-3 to moldm-3?

A

divide by Mr

36
Q

what are standard solutions?

A

Solutions that have been prepared by a chemist and have an accurate known concentration.

37
Q

what are the two main ways to prepare a standard solution?

A

-Dissolving a solid in distilled water
-Diluting a known concentration of existing solution with distilled water

38
Q

What is the preparation of standard solutions?

A
  1. -Measure known mass, by difference, using a mass balance
    -Dissolve in a small amount of water in a flask/beaker and then transfer 250cm3 to a volumetric flask (use a funnel)
    -Rinse the original flask with water and transfer washings to the volumetric flask
    -Carefully Make up to line with water (bottom of the meniscus on the line)
    -Stopper
    -Invert to mix
    • using a pipette transfer the original solution into a new volumetric flask
      -Carefully volumetric flask fill the volumetric flask to the line with more distilled water
      -Stopper
      -Invert to
39
Q

how do you calculate percentage uncertainty?

A

%uncertainty = (number of readings x uncertainty on equipment/ quantity measured) x 100

40
Q

How do you work out %yield?

A

%yield = actual/theoretical x 100

41
Q

What are reasons for percentage yield to be less than 100%?

A

-incomplete reaction
-Side products
-Reversible reaction
-Practical loss during experiment
-Impure Reactions

42
Q

what must you take into account in limiting moles question?

A

stoichiometric ratios

43
Q

what equation must you remember for limiting reagent?

A

initial mol/ratio

44
Q

What is atom economy?

A

A measure of how much waste a product a reaction produces

45
Q

What is sustainability?

A

-modern sustainability requires industry to operate processes with high atom, economies, and fewer pollutants.
-using view of fossil fuels, low carbon dioxide emissions, which should reduce global warming

46
Q

Why do addition reactions have atom economies of 100%?

A

as the desired compound is formed there are no byproducts, so there is no wastage, some other reaction types are more wasteful

47
Q

What does efficiency depend on?

A

Atomic economy and the yield

48
Q

What is a standard solution?

A

A solution of a know concentration

49
Q

What do you use for % yield?

A

moles

50
Q

What should you use instead of a beaker when making a solution?

A

250 volumetric flask