Chapter 3 Stochiometry

Question 1

Define unified atomic mass unit

Answer 1

This unified atomic mass is defined as one-twelfth of the mass of a carbon-12 isotope = 1.66 x 10-27 kg.

Question 2

Define relative atomic mass

Answer 2

The weighted average mass of atoms compared to the value of the unified atomic mass unit.

Question 3

Define relative isotopic mass

Answer 3

The mass of a particular atom of an isotope compared to the value of the unified atomic mass unit.

Question 4

Define relative molecular mass

Answer 4

The weighted average mass of a molecule compared to the value of the unified atomic mass unit. Only applicable for molecules with covalent bonds.

Question 5

Define formula unit

Answer 5

The simplest formula for a covalent giant structure or an ionic giant structure, eg SiO2.

Question 6

Define relative formula mass

Answer 6

The weighted average of one formula unit compared to the value of the unified atomic mass unit.

Question 7

Define mole

Answer 7

The amount of substance which contains 6.02x10^23 specified particles.

Question 8

Define Avogadro constant

Answer 8

The number of specified particles in a mole of those particles = 6.02x10^23

Question 9

[M+1] peak and [M+2] peak are caused by…

Answer 9

Carbon 13 isotope- [M+1].
Chlorine 37 and Bromine 81- [M+2].

Question 10

Formula for number of carbon atoms

Answer 10

n=100/1.1 x abundance of [M+1] ion/abundance of [M] ion.

Question 11

Ratio of M peak to M+2 peak of chlorine

Answer 11

3:1

Question 12

Ratio of M peak to M+2 peak of bromine

Answer 12

1:1