- I - Chemistry // Module 2 // Foundations in Chemistry - I -

Question 1

How do you calculate the Mass Number (A)?

Answer 1

Number of protons + Number of neutrons

Question 2

How do you calculate the number of Neutrons?

Answer 2

Mass Number (A) - Proton Number (Z)

Question 3

What are the number of protons and electrons?

Answer 3

They are the same (Z)

Question 4

What is Relative Atomic Mass (Ar)?

Answer 4

The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of Carbon-12.
E.g Chlorine has two isotopes.
Chlorine-35 (75%) and Chlorine-37 (25%)
∴ Ar = 35.5

Question 5

What is Relative Isotopic Mass?

Answer 5

The mass of an isotope relative to 1/12th of the mass of an atom of Carbon-12 and it is always an integer.

Question 6

What is the order of how Mass Spectrometry works?

Answer 6

1) Sample is placed in mass spectrometer
2) Sample is vapourised and ionised to form positive ions
3) Ions are accelerated and deflected by an electromagnet. Heavier ions are more difficult to deflect than lighter ions so the ions of each isotope are separated.
4) Ions are detected on a mass spectrometer as mass-to-charge ratio m/z. Heavier ion will be less deflected so will have greater m/z.
5)Each ion reaching the detector adds to the signal, so the greater the abundance, the larger the signal. Size of the signal is used to determine the abundance of each isotope.

Question 7

What is the shortened version of how Mass Spectrometry works?

Answer 7

V-Vaporised
I-Ionised
A-Accelerated
D-Deflected
D-Detected

Question 8

How do you determine Relative Atomic Mass (RAM)?

Answer 8

Ar= (Relative Isotopic mass of Isotope 1 X Percent abundance of Isitope 1) + (Relative Isotopic mass of Isotope 2 X Percent abundance of Isotope 2) + … (if needed) /100

Question 9

How do you calculate the amount of substance (mol)?

Answer 9

m=nXM
m- Mass (g)
n- Amount of a substance in Moles (mol)
M- Molar mass (g/mol)

Question 10

What is water of crystallisation?

Answer 10

Water molecules that are bonded into a crystalline structure of a compound.

Question 11

How can we remove all water from hydrous crystals?

Answer 11

Heat crystals until a constant mass is reached.

Question 12

What colour is hydrous and anhydrous copper (II) sulphate?

Answer 12

Hydrous- Blue
Anhydrous- White

Question 13

What are two assumptions that are made about the accuracy of an experimental formula?

Answer 13

Assumption 1- All of the water has been lost.
Assumption 2- There is no further decomposition when the crystal is heated.

Question 14

How can you convert cm^3 to dm^3 ?

Answer 14

X1000

Question 15

How can you convert dm^3 to cm^3 ?

Answer 15

Multiply by 1000

Question 16

What is 1cm^3 in ml?

Answer 16

1cm^3 is 1ml

Question 17

What is 1dm^3 in litres ?

Answer 17

1dm^3 is 1000cm^3 = 1000ml = 1litre

Question 18

What is a solute?

Answer 18

A substance that dissolves in a solvent

Question 19

What is a solvent?

Answer 19

A liquid which a solute dissolves into a solution

Question 20

What is a solution?

Answer 20

Mixture formed by a solvent and solute.

Question 21

What is the formula to calculate the number of moles using concentration?

Answer 21

n=cXV
n- number of moles
c- Concentration (mol dm^-3)
V- Volume in dm^3

Question 22

What is the formula for molar volume?

Answer 22

V=nX24
V- Volume in dm^3
n- amount in moles

Question 23

How do you convert degrees celsius into Kelvin?

Answer 23

+273

Question 24

How do you convert cm^3 to m^3 ?

Answer 24

x10^-6

Question 25

How do you convert dm^3 to m^3 ?

Answer 25

x10^-3

Question 26

How do you convert kPa to Pa?

Answer 26

x1,000

Question 27

What is the ideal gas equation?

Answer 27

pV=nRT
p- pressure (Pa)
V- Volume (m^3)
n- amount of gas molecules (mol)
R- ideal gas constant (8.31J mol^-1 K^-1)
T- Temperature (K)

Question 28

What is the ideal gas constant?

Answer 28

8.31J mol^-1 K^-1

Question 29

What is stoichiometry?

Answer 29

The ratio of the amount, in moles, of each substance in a chemical equation