chemical calculations

Question 1

what is a mole?

Answer 1

the unit for measuring the amount of a chemical we have

Question 2

how many particles does 1 mole equal?

Answer 2

6.02 x 10^23

Question 3

1 mole of an element will equal how many grams?

Answer 3

the number of grams 1 mole of an element is is its relative atomic mass.

Question 4

formula for moles

Answer 4

number of moles=
mass of element or compound / Mr

Question 5

what is relative formula mass?

Answer 5

sum of relative atomic masses of the atoms, in the numbers shown

Question 6

concentration formula

Answer 6

concentration (mol/dm3) = amount / volume

Question 7

what is the atom economy of a reaction?

Answer 7

a measure of the amount of starting materials that end up as useful products.

Question 8

atom economy formula

Answer 8

atom economy =
total Mr of the desired product
——————————————- × 100
total Mr of all reactants

Question 9

percentage yield

Answer 9

theoretical yield is the maximum possible mass of a product that can be made in a chemical reaction.

Question 10

percentage yield formula

Answer 10

percentage yield =
mass of product actually made
——————————————— × 100
maximum theoretical mass of product

Question 11

equilibrium position

Answer 11

A measure of the relative concentrations of substances in an equilibrium, showing if there are more reactants or products at equilibrium.

Question 12

Avogadro’s law -
when temperature and pressure stay the same:

Answer 12

• equal volumes of different gases have an equal number of molecules

Question 13

how to use avogadro’s law in questions

Answer 13

• work out the mole ratio between reactants and products in the question
• divide amount of grams in question by the first number in the ratio
• then times by the second number in the ratio

Question 14

molar volume

Answer 14

the volume occupied by one mole of any gas, at room temperature and pressure