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GENERAL IGCSE Chemistry > Stoichiometry > Flashcards

Flashcards in Stoichiometry Deck (19)
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1
Q

What is relative atomic mass (Ar)?

A

average mass of naturally occurring atoms of an element on a scale where the 12C atom has a mass of exactly 12 units

2
Q

What is relative molecular mass? (Mr)

A

sum of the relative atomic masses

3
Q

What is relative formula mass?

A

Relative molecular mass for ionic compounds

4
Q

How can solution concentrations be expressed?

A

mol/dm3 or g/dm3

5
Q

Moles =

A

Concentration x Volume

6
Q

What is a mole?

A

the number of particles which is equal to the number of atoms in 12g of carbon 12

7
Q

What is Avogadro’s constant? (3)

A

number of particles / atoms / ions / molecules in one mole of a substance
the number of particles / molecules in 24dm3 of a gas at RTP

8
Q

What is the number of particles in 24 dm3 of a gas at RTP?

A

6 to 6.0^23 × 10^23 atoms (Avogadro’s constant)

9
Q

no. of moles =

A

mass of substance taken/mass of one mole of substance

10
Q

What is the limiting reactant?

A

the one that is not in excess

11
Q

How can we calculate the limiting reactant?

A

Calculate which reactant has the lower number of moles

12
Q

Excess of substance =

A

moles of substance at start - moles of substance at end

13
Q

n =

A

M/mr

14
Q

concentration =

A

number of moles / volume

15
Q

volume of gas (in dm3) =

A

number of moles x 24

16
Q

% by mass of element in compound =

A

sum of Mr/ relative formula mass of compound x 100

17
Q

% yield =

A

actual yield/predicted yield x 100

18
Q

% purity =

A

mass of pure product/mass of impure product x 100

19
Q

What are the 6 formulas you need to know?

A

.