3.1.2 Amount of substance

Question 1

EQUATION Work out number of moles.

Answer 1

1. N = M / Mr
   mol = g / gmol-1
2. N = C V
   mol = moldm-3 X dm3

Question 2

How to get from cm3 to dm3?

Answer 2

/1000

Question 3

EQUATION Work out number of particles

Answer 3

Number of particles = moles X avogadros constant.
Number of particles = mol X 6.022 x10^23

Moles applied to electrons, atoms, molecules, ions

Question 4

EQUATION Work out mass concentration.

Answer 4

Mass concentration = mass / volume
gdm-3 = g / dm-3

Question 5

EQUATION Work out concentration in gdm-3.

Answer 5

Conc. in gdm-3 = conc. in moldm-3 (given or calculated) X mr
= mol/dm-3 X g/mol
=gdm-3

Question 6

EQUATION Ideal gas equation.

Answer 6

PV = nRT
(Pressure) (Volume) = (moles)(Gas constant) (temperature)
(Pa)(m3) = (mol)(JK-1mol-1) (K)

cm3 to m3 = x10-6
* C to K = +273

Question 7

EQUATION Dilution

Answer 7

Diluted concentration = conc. intial x (volume intial / vol. diluted)

Question 8

What will happen to the concentration when you dilute a solution or so with distilled water?

Answer 8

As the volume of the solution increases, the concentration of the solution decreases.

n = cv -> c =n/v

Question 9

EQUATION % Yield.

Answer 9

% yield = (actual yield / theoritical yield) x 100

Actual yield = given in question
Theoritical = we calculate it

Question 10

EQUATION % atom economy

Answer 10

% atom economy = (mass (products) / mass of all reactants) x 100

Question 11

EQUATION % uncertainty.

Answer 11

% uncertainty = ( (+ or - uncertainity) / appartatus measurement ) x 100

i.e: burette = + or - 0.15 cm3