Amount Of Substance

Question 1

What is a mole

Answer 1

• the amount of substance in grams that has the same number of particles as there are atoms in 12 grams of carbon-12

Question 2

Relative molecular mass

Answer 2

The average mass of a molecule compared to 1/12 the mass of one atom of carbon-12

Question 3

Equations for moles

Answer 3

Moles = mass/Mr

Question 4

Equation for gases

Answer 4

PV = nRT

Question 5

Equation for concentration

Answer 5

Concentration - moles/volume

Question 6

Equation for number of particles

Answer 6

Number of particles = number of moles x avogadro’s constant

Question 7

Units for calculating moles

Answer 7

Mass - grams

Moles - mol

Question 8

Units for calculating gases

Answer 8

Pressure - Pa
Volume - m^3
Temperature - K
n - mol
R - 8.31

Question 9

Units for calculating concentration

Answer 9

Moles - mol
Concentration - mol dm-3
Volume - dm3

Question 10

Equation for density

Answer 10

Density = mass/volume

Question 11

Units for density

Answer 11

Density = g/cm-3
Mass - grams
Volume - cm^3

Question 12

How to make a solution for titration

Answer 12

1. Known concentration of solid
   - place weighing boat onto balance and record mass (M1)
   - add the amount of solid to board and record mass (M2)
   - add mass to beaker and record mass of boat again (M3)
   - subtract M2-M3 that will give exact mass of solid added.
2. Dissolve known solution
   - use distilled water
   - stir until fully dissolved using a glass rod
3. Known concentration of liquid
   - use a 250 cm3 volumetric flask
4. • transfer dissolved solution into flask using funnel
   • rinse beaker with distilled water and do multiple washings until it is level with the line.
   • place stopper and invert to mix solution thoroughly

Question 13

Conversions for

• cm3 - dm3 - m3
• mPa - kPa - Pa

Answer 13

Question 14

Conversion for degrees Celsius into kelvin

Answer 14

Add 273

Question 15

Calculating diluted concentration equation

Answer 15

New diluted conc = original conc x (original vol/new diluted vol)

Question 16

Calculating percentage uncertainty equation

Answer 16

% uncertainty = +/- uncertainty/ measurement made on apparatus x 100