Amount of Substance

Question 1

What is relative molecular mass?

Answer 1

The mean mass of a molecule of a compound divided by 1/12 of the mean mass of an atom of the carbon-12 isotope.

Question 2

What do ionic compounds use instead of relative molecular mass?

Answer 2

Relative formula mass.

Question 3

What is a mole?

Answer 3

A unit of measurement for substances. It always contains the same number of particles.

Question 4

What is the Avogadro’s constant?

Answer 4

6.022 x 10^23

Question 5

What is L?

Answer 5

Avogadro’s constant.

Question 6

How do you calculate number of particles?

Answer 6

Moles of substance x Avogadro’s constant

Question 7

What is the Avogadro’s constant?

Answer 7

It allows the number of particles present in a sample of substance with known mass to be found.

Question 8

How to calculate moles in pure solids, liquids and gases?

Answer 8

Moles = Mass/Mr

Question 9

What is mass measured in?

Answer 9

Grams

Question 10

What is Mr measured in?

Answer 10

Mol to 1 d.p

Question 11

What equation is used for gases?

Answer 11

PV = nRT
P = Pressure (Pa)
V = Volume (m^3)
n = Moles of substance (mol)
R = 8.31
T = Temp (K)

Question 12

How to convert from Degrees Celsius to Kelvin?

Answer 12

Add 273 degrees.

Question 13

What equation is used for solutions?

Answer 13

Concentration = Moles/Volume

Question 14

What is concentration measured in?

Answer 14

Mol dm ^-3

Question 15

What is volume measured in?

Answer 15

dm^3

Question 16

1000mg to g?

Answer 16

1g

Question 17

1000g to kg?

Answer 17

1kg

Question 18

1000kg to tonne?

Answer 18

1 tonne

Question 19

How to convert from cm^3 to dm^3?

Answer 19

Divide by 1000

Question 20

How to convert from cm^3 to m^3?

Answer 20

Divide by 1 million.

Question 21

How to convert from dm^3 to m^3?

Answer 21

Divide by 1000

Question 22

What can Avogadro’s constant be used for?

Answer 22

Molecules
Atoms
Ions

Question 23

Density equation?

Answer 23

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

Question 24

What is an empirical formula?

Answer 24

The simplest ratio of atoms of each element in the compound.

Question 25

What are density calculations used for?

Answer 25

Pure liquids to work out the mass from a measured volume. It can also be used with solids and liquids.

Question 26

What is a molecular formula?

Answer 26

A molecular formula is the actual number of atoms of each element in the compound.

Question 27

Why must chemical equations be balanced before being used in calculations?

Answer 27

The reacting ratios must be correct.

Question 28

What can balanced chemical equations be used to calculate?

Answer 28

Percentage Yield
Atom Economy
Reacting Masses

Question 29

Percentage yield equation?

Answer 29

(Experimental mass/theoretical mass) x 100

Question 30

Atom economy equation?

Answer 30

(Mr of desired product/Mr of reactants) x 100

Question 31

Is a low or high atom economy desirable in industrial chemical processes? Why?

Answer 31

High because it means there is little to no waste product, only the desired product. Thus the process is more economically viable for industrial scale manufacture.

Question 32

Why is having high atom economy beneficial for the environment?

Answer 32

It uses less natural resources and thus often uses less energy.

Question 33

Amount of substance Equation?

Answer 33

Mass/Molar Mass

Question 34

Number of particles equation?

Answer 34

Amount of substance x Avogadro’s Constant