MOLES

Question 1

What is meant by relative atomic mass?

Answer 1

The weighted mean mass of an atom of an element relative to an atom of carbon-12 having a mass of exactly 12

Question 2

What is meant by the term molecular mass?

Answer 2

The weighted average mass of a relative to an atom of carbon-12 having a mass of exactly 12 units.

Question 3

What is meant by the term relative atomic mass?

Answer 3

The mass of an atom of an isotope on a scale relative to an atom of carbon-12 having a mass of exactly 12 units.

Question 4

What is meant by relative formula mass?

Answer 4

The weighted average of the masses of the formula units relative to an atom of carbon-12 having a mass of exactly 12 units.

Question 5

What is meant my the term amount of substance?

Answer 5

• It is measured in moles
• Avogadro’s constant
• Measures the number of atoms in a substance.

Question 6

Avogadro’s constant

Answer 6

6.02 x 10^23
No. of atoms per mole of a substance

Question 7

Define the mole

Answer 7

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

Question 8

How can the mass spectrum tell us the relative atomic mass?

Answer 8

Peak with the highest m/z value (molecular ion peak) due to the whole molecule after one e- has been knocked off.
m/z value of m+ peak = molecular mass

Question 9

What is meant by the term empirical formula?

Answer 9

The simplest whole no. ratio of atoms of each element present in the compound.

Question 10

Define molecular formula

Answer 10

The actual no. of atoms of each element present in a compound.

Question 11

What is meant by concentration?
Equation of concentration?

Answer 11

The amount of solute dissolved per dm^3 of solution.
n=cv

Question 12

Equation of Molecular mass, moles?

Answer 12

n= m/Mr

Question 13

Equation of volume of gas?

Answer 13

n= v/24