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AQA A Level Physical Chemistry > 2. Amount Of Substance > Flashcards

Flashcards in 2. Amount Of Substance Deck (65)
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1

Why are all mass relative to carbon-12?

1/12 of its relative atomic mass is 1

2

How can relative atomic mass (Ar) be defined?

The weighted average mass of an atom of an element, taking into account its isotopes, relative to 1/12 of the relative atomic mass of an atom of carbon-12

3

How can relative atomic mass be calculated?

average mass of one atom of an element / 1/12 mass of one atom of carbon-12

4

How can relative molecular mass (Mr) be defined?

The mass of that molecule compared to 1/12 of the relative atomic mass of an atom of carbon-12

5

How can relative molecular mass be calculated?

average mass of one molecule / 1/12 mass of one atom of carbon-12

6

What do ionic compounds exist as instead of molecules?

Ionic lattices

7

What is used for ionic compounds instead of relative molecular mass?

Relative formula mass

8

Why is relative formula mass used for ionic compounds?

They form ionic lattices instead of molecules

9

What does the formula of an ionic compound show?

The simplest ratio of ions in the compound

(instead of the total number of atoms in the compound)

10

What is the mole defined as?

The amount of substance that contains 6.022e23 particles

11

How many particles are in one mole of a subtance?

6.022e23 (electrons, atoms, molecules, ions or compounds)

12

What equation is used to work out number of moles (using mass and mr)?

n = mass / mr

13

What is the final answer usually given to?

3 significant figures

14

How many decimal places should Mr be calculated to?

1

15

What is the concentration of a solution?

The amount of solute present in a fixed quantity of solvent

16

What is concentration measured in?

g/dm³ or mol/dm³

17

What is the molarity?

The concentration (in mol/dm³)

18

How can number of moles be calculated (when given conc. and volume)?

n=cv

19

g/dm³ to mol/dm³?

÷ Mr

20

mol/dm³ to g/dm³?

x Mr

21

What is a titration?

The procedure of reacting volumes

22

During a titration, what is placed in the burette?

The solution of known concentration

23

During a titration, what is placed in the conical flask?

The solution of unknown concentration

24

What is the law of conservation of mass?

Mass of reactants = Mass of products

25

What does the volume a gas occupies depend on?

• temperature

• pressure

• amount of gas

26

How does the temperature of a gas influence the volume it occupies?

The hotter the gas, the faster the particles move and the more space they occupy

27

How does the pressure of a gas influence the volume it occupies?

The higher the pressure, the more compressed the gas will be and the less space it will occupy

28

How does the amount of a gas influence the volume it occupies?

The more gas particles there are, the more space they will occupy

29

What is the ideal gas law?

One mole of any gas, at the same temperature and pressure, will have the same volume as one mole of any other gas

30

What is the equation for the ideal gas law?

PV = nRT