Stoichiometry

Question 1

What is relative atomic mass?

Answer 1

the average mass of the isotopes of an element compared to 1/12th of the mass of an atom of carbon-12

Question 1

What is Ar?

Answer 1

relative atomic mass

Question 2

Relative atomic mass can be written as…

Answer 2

Ar

Question 2

What is relative molecular mass?

Answer 2

the sum of the relative atomic masses

Question 3

What is Mr?

Answer 3

relative molecular mass

Question 3

Relative molecular mass can be written as…

Answer 3

Mr

Question 3

What is the mole?

Answer 3

the unit of amount of substance

Question 3

How many particles are in one mole?

Answer 3

6.02 × 10^23

Question 4

What is the Avogadro constant?

Answer 4

6.02 × 10ˆ23: the number of particles in one mole

Question 5

One mole contains 6.02 × 10ˆ23 _____.

Answer 5

particles- includes atoms, ions, molecules…

Question 6

moles =

Answer 6

mass/molar mass

Question 7

What is an empirical formula?

Answer 7

the simplest whole number ratio of the different atoms or ions in a compound

Question 8

What is a molecular formula?

Answer 8

as the number and type of different atoms in one molecule

Question 9

volume of gas at r.t.p =

Answer 9

moles x 24
answer in dmˆ3

Question 10

What is concentration measured in?

Answer 10

g /dm3 or mol/dm3

Question 11

Formula for calculation volumes and concentrations

Answer 11

n = c x v
moles = conc x vol

Question 12

How can you convert concentrations from mol/dm3 to g/dm3?

Answer 12

multiplying the concentration in mol/dm3 by the Mr of the substance

Question 13

formula for % composition of an element

Answer 13

(Ar x number of atoms / mr of compound) x100

Question 14

% yield formula

Answer 14

(actual/theoretical) x 100

Question 15

formula for % purity

Answer 15

(mass of pure/mass of impure) x 100