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Chemistry OCR A A level > Amount of Substance > Flashcards

Amount of Substance Flashcards

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1
Q

What is Avogadro’s constant? What does it mean?

A

6.02 x 10^23- the number of particles in each mole of carbon 12

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2
Q

What is the mass of one mole of any substance equal to?

A

Relative atomic mass in grams

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3
Q

What equation links moles, mass, mr?

A

Mass= Mr x Mol

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4
Q

What is the empirical formulae?

A

The simplest whole number ration of atoms of each element in a compound

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5
Q

Define relative molecular mass

A

The mass of a molecule compared with the mass of an atom of carbon-12

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6
Q

Define relative formula mass

A

The mass of a formula unit compared with the mass of an atom of carbon-12

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7
Q

What is ‘analysis’?

A

Investigation of the chemical composition of a substance

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8
Q

Define ‘water of crystallisation’

A

Water molecules are part of their crystalline structure

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9
Q

What are the two assumptions made when calculating formula of a dehydrated salt?

A

All of the water has been lost

No further decomposition

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10
Q

What is 1dm^3 in cm^3?

A

1000cm^3

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11
Q

What equation links moles, volume and concentration?

A

moles= concentration x volume

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12
Q

What is a standard solution?

A

A solution of a known concentration

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13
Q

What is the molar gas volume?

A

The volume per mole of gas molecules at a stated temperature and pressure

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14
Q

What is RTP?

A

20 C, 101kPa

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15
Q

What is molar gas volume at RTP?

A

24.0 dm3 mol-1

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16
Q

What are the assumptions made in an ideal gas equation?

A

Random Motion
Elastic collisions
Negligible size
No intermolecular forces

17
Q

What is the ideal gas equation?

A

pV=nRT

Pressure x volume = moles x ideal gas constant x temperature

18
Q

What are the units used in ideal gas equation?

A 
Pressure= Pa
Volume= m^3
Moles= mol
Ideal Gas Constant= mol-1 k-1
Temperature= K
19
Q

What is the value of the ‘ideal gas constant’?

A

8.31

20
Q

Why can the theoretical yield not always be reached?

A

Reaction may not have gone to completion
Other reactions may have taken alongside reaction
Purification may result in some lost product

21
Q

What is the equation for percentage yield?

A

actual yield/ theoretical yield x 100

22
Q

What is the limiting reagent?

A

The reactant that will be completely used up first in a reaction and that will cause the reaction to stop

23
Q

What is atom economy a measure of?

A

Measure of how well atoms have been utilised

24
Q

Why are high atom economies important?

A

Sustainability
Produce little waste products
Preserves raw materials

25
Q

What is the equation for atom economy?

A

Sum of molar masses of desired product/ sum of molar masses of all products x 100

Chemistry OCR A A level (20 decks)

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