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OCR Chemistry A Level 2015 > Amount Of Substance > Flashcards

Flashcards in Amount Of Substance Deck (30)
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1

What does amount of substance mean?

The quantity whose unit is the mole

2

What does mole mean?

Amount of any substance containing as many particles as there carbon atoms in exactly 12g of carbon-12 isotope

3

What does the Avogadro constant mean?

The number of atoms of the carbon-12 isotope (6.02 * 10 to the 23)

4

What does molar mass mean?

Mass per mole of a substance measured by grams per mole

5

What does molar volume mean?

Volume per mole of a gas measured by mole per decimetre cubed

6

What does empirical formula mean?

Simplest whole number ratio of atoms of each element present in a compound

7

What does molecular formula mean?

Actual number of atoms of each element in a molecule

8

What does hydrated mean?

Refers to a crystalline compound containing water molecules

9

What does anhydrous mean?

Refers to a substance that contains no water molecules

10

What does water of crystallisation mean?

Refers to water molecules that form an essential part of the crystalline structure of a compound

11

What does concentration mean?

Amount of solute in moles dissolved in one decimetre cubed of solution

12

What is the ideal gas equation?

pV = nRT

13

What is p?

Pressure

14

What is P measured in?

Pa

15

How do you convert KPa to Pa?

Multiply by 1000

16

What is V?

Volume

17

What is V measured in?

Metres cubed

18

How do you convert from centimetre cubed to metre cubed?

Divide by 1,000,000

19

How do you convert from decimetre cubed to metre cubed?

Divide by 1,000

20

What is n?

Number of moles

21

What is R?

The ideal gas constant

22

What is T?

Temperature

23

How do you convert from degrees Celsius to kelvin?

+ 273k

24

What is temperature measured in?

Kelvin

25

When do we use the ideal gas equation?

When it is not room temperature and pressure

26

Why is 100% percentage yield very difficult to achieve?

1) Reversible reaction
2) Reactants may contain impurities
3) By-products may be formed from unexpected reactions
4) Reactants/products may be left in apparatus during the experiment
5) Product may be lost during separation and purification, such as being soaked onto filter paper

27

How do you calculate percentage yield?

Actual amount over theoretical amount of product in terms of moles or mass times by 100

28

What is atom economy?

Considers the efficiency of a reaction by looking at the proportion of the products formed that are actually used

29

Why are reactions with high atom economies so important?

They make better use of finite resources and reduce the need to process and safely dispose of waste products

30

How do you calculate atom economy?

Molecular mass of desired product over the sum of the molecular masses of all products times by 100