Chapter 2 (Amount of Substance)

Question 1

Define relative atomic mass

Answer 1

The average mass of an atom of an element relative to the mass of 1/12 of a carbon 12 atom.

Question 2

Define relative molecular mass

Answer 2

The average mass of one molecule relative to the mass of 1/12 of a carbon 12 atom.

Question 3

How do you find Mr of a molecule?

Answer 3

Add all the relative atomic masses of the atoms in the molecule.

Question 4

What is Avogadro’s constant?

Answer 4

6.022 x 10^23

Question 5

What is Avogadro’s constant used for?

Answer 5

Finding the number of atoms in 1g of that element.

Question 6

What is a mole?

Answer 6

The amount of substance that contains 6.022 x 10^23

Question 7

What is the equation to find moles?

Answer 7

n (moles) = mass (g)/ Mr

Question 8

What is the equation for finding moles in a solution?

Answer 8

n (moles) = (concentration (mol dm-3) x volume (cm3))/ 1000

Question 9

What is the ideal gas law?

Answer 9

Pressure x Volume = Moles x Gas Constant x Temperature

P = Pa
V = m3
Gas Constant = 8.31 JK-1 Mol-1
T = Kelvin

Question 10

How do you find empirical formula?

Answer 10

1) Find mass of each element present in compound.
2) Work out Moles (Mass/Mr)
3) Convert Moles of each element into a number ratio.

Question 11

How do you find molecular formula?

Answer 11

Relative molecular mass/ Relative mass of empirical formula

Question 12

What is the equation for atom economy?

Answer 12

(mass of desired product/total mass of reactants) x 100

Question 13

Waht is the equation for yield?

Answer 13

(mass of product obtained/ theoretical maximum mass of product) x 100