Amount Of Substance (Completed)

Question 1

Define a mol

Answer 1

The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon -12 isotope

Question 2

What is the number of particles per mole called and what is this number

Answer 2

Avogadro’s constant
6.02×10²³

Question 3

What is molar mass And what are the units for it

Answer 3

The mass per mole of a substance

Question 4

How do you work out the molar mass of a substance

Answer 4

The molar mass is calculated in the same way as relative formula masses- add together all relative atomic masses

Question 5

Define empirical formula

Answer 5

The simplest whole number ratio of atoms of each element present in a compound

Question 6

Define the term ‘hydrated’

Answer 6

A crystalline compound which contains water molecules in its structure

Question 7

Define the term ‘Anhydrous’

Answer 7

A compound left when all the water of crystallisation has been removed

Question 8

Define the term ‘water of crystallisation’

Answer 8

Water molecules that form an essential part of the crystalline structure of a compound

Question 9

Give the 2 assumptions we use in water of crystallisation calculations

Answer 9

1) all of the water has been lost

2) theres been no further decomposition

Question 10

Give a solution to the risk of assuming all water of crystallisation has been removed

Answer 10

Keep heating and checking the mass until there’s no further change in mass

Question 11

How many grams are in 1 tonne

Answer 11

1,000,000 grams

Question 12

Answer 12

Multiply the concentration by the molar mass of the substance

Question 13

How many cm³ are in 1cm³

Answer 13

1000

Question 14

What is a standard solution

Answer 14

A solution that has a known concentration

Question 15

Give the 2 steps of how to make up a given volume of a solution with a precise concentration

Answer 15

1. Work out the amount in moles of the solution required
2. Calculate the mass of solute needed for the chosen volume of water

Question 16

Give 4 reasons why percentage yields of 100% are rarely obtained

Answer 16

1) the reaction may be at equilibrium, therefore may not Go to completion

2) other side reactions may take place, leading to by-products

3) the reactants may not be pure

4) some of the reactants or products may be left in the apparatus used in the experiment

Question 17

Give the formula for percentage yield

Answer 17

Question 18

What is the formula for atom economy

Answer 18

Question 19

Practice some amount of substance questions

Answer 19

Done