Calculations

Question 1

Titration Calculation

Answer 1

1. Write a balanced equation to determine the molar ratio
2. Find the moles of known solution : n = c x v
3. Find the moles of unknown solution using molar ratio
4. Use n = c x v to find the unknown concentration

Question 2

Titration calculation to find the mass of a solid used to make up a solution

Answer 2

1. Write balanced equation to determine molar ratio
2. Find moles of known solution using n = c x v
3. Find moles in unknown solution used in titration by using the molar ratio
4. Find moles in original (standard) solution by scaling up to original volume
5. Find mass by using mass = n x Mr

Question 3

Titrations to find moles in a standard solution

Answer 3

1. Divide moles by current volume
2. Multiply by the new volume

Question 4

Calculating particles from mass

Answer 4

Number of particles = moles of the particle x Avogadros number

Question 5

Finding mass of one mole of atoms using Avogadro’s number

Answer 5

Mass of one mole of atoms = mass of one atom x Avogadro’s number

Question 6

Equation for amount of substance

Answer 6

Moles = mass / Mr

Question 7

Calculating molecular formula

Answer 7

Molecular formula = ratio x empirical formula

Question 8

Calculating % uncertainty

Answer 8

( number of readings x uncertainty of equipment) / quantity x 100

Question 9

Calculating moles of gas at RTP

Answer 9

Moles = volume / 24 dm3 (24 000 cm3)

Question 10

Calculating moles of gat not at RTP

Answer 10

PV = nRT

Question 11

Calculating moles of a solution

Answer 11

N = c x V

Question 12

The g dm3 unit of concentration

Answer 12

Concentration in g dm3 = concentration in mol dm3 x Mr

Question 13

Equation for heat exchanged ( enthalpy )

Answer 13

Q = mass of the surroundings x c x change in temperature