P1- Quantitative chemistry

Question 1

How to work out relative atomic mass (Ar)

Answer 1

(Abundance X Mass) + (Abundance X Mass) divided by 100

Question 2

How to work out relative formula mass (Mr)

Answer 2

(Number of element x It’s mass number) + (Number of element x It’s mass number)

Question 3

How to calculate percentage by mass

Answer 3

Ar of the element divided by Mr of the compound x 100

Question 4

What is conservation of mass

Answer 4

The total mass of the products formed in a reaction is equal of the total mass of the reactants

Question 5

What is an uncertainty

Answer 5

An error within a measurement, every measurement made will have some uncertainty within it. The uncertainty in a result is +/- the smallest increment of a scale

Question 6

What is a mole

Answer 6

A unit of amount of substance- one mole of a substance is the relative formula mass of that substance in grams

Question 7

How to calculate the number of moles

Answer 7

Mass in grams (element or compound) divided by the relative formula mass (Mr)

Question 8

How to calculate the number of atoms and molecules in a mole

Answer 8

Calculate the number of moles and multiply this by avogadro’s constant

Question 9

What is avogradro’s constant

Answer 9

6.02 x 10^23

Question 10

How to do mass calculations

Answer 10

Using the ratio step grid with ratio, mass, mr, moles and ratio step and your known and unknown mass

Question 11

How to calculate concentration when involving solvents

Answer 11

moles of solute (g) divided by the volume of the solvent (dm3)

Question 12

How to calculate concentration using mass

Answer 12

Mass divided by volume

Question 13

What is concentration

Answer 13

The amount of substance (solute) dissolved in a certain volume of the solvent to create a solution. The unit used can be grams per dm3

Question 14

How to convert from cm3 to dm3

Answer 14

divide by 1000 (x for dm3 to cm3)

Question 15

How to convert from g/dm3 to mol/dm3

Answer 15

divide by the relative formula mass (Mr)

Question 16

Why is it not always possible to obtain the full amount of product even though no atoms are gained or lost in a chemical reaction

Answer 16

The reaction may not go to completion because it is reversible, some of product may be lost when it is separated from the reaction mixture, some of reactants may react in ways different to the expected reaction

Question 17

How to calculate percentage yield

Answer 17

Actual mass divided by theoretical mass x 100

Question 18

Percentage yield table

Answer 18

Both compounds at the top and ratio, mass, mr and moles at the side of

Question 19

What is atom economy

Answer 19

amount of starting materials that end up as useful products. it is important for reactions with high atom economy

Question 20

First way to calculate atom economy

Answer 20

Ar(Mr) of desired products divided by the sum of Mr of all the reactants x 100

Question 21

Second way to calculate atom economy

Answer 21

Ar(Mr) of desired products divided by the sum of Mr of all the products x 100

Question 22

At room temperature and pressure (RTP) what will one mole of any gas occupy a volume of

Answer 22

24dm3

Question 23

What is room temperature

Answer 23

20 degrees celsius

Question 23

What is room pressure

Answer 23

1 atmosphere

Question 24

How to calculate volume (dm3)

Answer 24

Number of moles x 24

Question 25

What does concentration tell us

Answer 25

The mass of a solute in a given volume of solution

Question 26

How to calculate moles using concentration and volume

Answer 26

Number of moles = concentration x volume

Question 27

How to calculate mass using moles and Mr

Answer 27

Mass = Number of moles x Relative formula mass