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A Level Chemistry > Chapter 3 - Amount of Substance (MODULE 2) > Flashcards

Chapter 3 - Amount of Substance (MODULE 2) Flashcards

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1
Q

What is avogadro’s constant

A

6.02 x 10^23

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2
Q

What is 6.02x10^23 molecules of a substance known as

A

a mole

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3
Q

How can one mole of a substance easily be calculated

A

relative atomic mass in grams

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4
Q

What is molar mass
- what are the units

A

mass in grams of a mole of a substance
- g/mol

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5
Q

What equation links mass, molar mass and number of moles

A

moles = mass / Mr

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6
Q

What is the molecular formula

A

number of atoms of each element in a compound

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7
Q

What is the empirical formula

A

simplest whole number ratio of atoms of each element in a compound

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8
Q

What is the relative molecular mass

A

comparison of the mass of a molecule with the mass of 1/12 of carbon 12

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9
Q

What is the relative formula mass

A

compares the mass of a formula unit with the mass of carbon-12

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10
Q

what does it mean for a crystal to be hydrated
- what is this known as

A

water molecules are a part of their crystalline structure
- water of crystallisation

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11
Q

how can water of crystallization be removed

A

heating to evaporate until mass is constant

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12
Q

How is water of crystallization indicated on a compound

A

large dot between compound and water units

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13
Q

What are two assumptions made when when heating hydrated compounds to make anhydrous compounds

A
  1. all water has been lost
  2. no further decomposition of salts / crystals
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14
Q

how many cm3 is a litre and millilitre

A

litre: 1000cm3 / 1dm3
millilitre : 1cm3

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15
Q

What is the equation linking moles, concentration and volume

A

moles = concentration x volume

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16
Q

What is a standard solution

A

a solution of known concentration

17
Q

How are standard solutions made

A

dissolve an exact mass of solute in a solvent and make up the solution to an exact volume

18
Q

What is the equation linking molar concentration and mass concentration

A

mass concentration = molar concentration x Mr

19
Q

what is the molar gas volume

A

volume per mole of gas at a stated temperature and pressure

20
Q

What is RTP approximately valued at

A

20 degrees C and 101kPa (1 atm)

21
Q

What is the volume of 1 mol of gas at RTP
- What is the molar gas volume at RTP

A

24 dm3
- 24 dm3 / mol

22
Q

What are the four assumptions made for the molecules making up an ideal gas

A
  • random motion
  • elastic collisions
  • negligible size
  • no intermolecular forces
23
Q

what is the ideal gas equation

A

pV = nRT

pressure x volume = moles x ideal gas constant x temperature

24
Q

What are the units used in the ideal gas equation

A

pressure - Pa
Volume - m^3
Temperature : Kelvin

25
Q

What is the ideal gas constant

A

8.31 J/ (mol K)

26
Q

How to convert from:

cm^3 to m^3
cm^3 to dm^3
dm^3 to m^3
celsius to kelvin
Pascals to KiloPascals

A

x 10^-6
x 10^-3
x 10^ -3
+ 273
x 10^-3

27
Q

What is the stoichiometry of a reaction

A

the ratio of moles of each substance in a reaction

28
Q

What are two reasons balanced equations are used

A
  • to work out how much reactant is needed to prepare a certain amount of product
  • quantities of products that should be prepared from a certain amount of reactant
29
Q

What is percentage yield (not the equation)

A

the actual yield of a reaction compared to the theoretical yield

30
Q

What is the equation for percentage yield

A

(actual yield / theoretical yield ) x 100

31
Q

What are three reasons as to why the percentage yield may not be 100%

A
  • reaction may not have gone to completion
  • other reactions may have taken place alongside the main reaction
  • purification of the product may have led to loss in some product
32
Q

What is the limiting reagent

A

the reactant that is not in excess - all is used up and limits more reaction from happening

33
Q

What is atom economy

A

a measure of how well atoms have been utilised

34
Q

What is the equation for atom economy

A

sum of molar mass of desired products / sum of molar mass of all products x 100

35
Q

Why is a high atom economy desirable

A

less waste and makes the best use of natural resources

36
Q

what factors other than atom economy affect sustainability of a reaction

A
  • availability of resources
  • percentage yield

A Level Chemistry (16 decks)

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