2.1.1, 2.1.2, 2.1.3

Question 1

What is used to identify an element?

Answer 1

Atomic number

Question 2

What is the relative mass of an electron?

Answer 2

1 / 1836

Question 3

What letters represent mass and atomic number?

Answer 3

Mass = A
Atomic = Z

Question 4

What is an isotope?

Answer 4

Atoms of the same element with different numbers of neutrons and different mass numbers but the same number of protons and electrons.

Question 5

Why do different isotopes of an element react in the same way?

Answer 5

Same number of electrons, number of neutrons has no impact on reaction.

Question 6

What is the mass defect?

Answer 6

The strong nuclear force holding together protons and neutrons causes a fraction of the isotope’s mass to be lost.

Question 7

What is carbon-12?

Answer 7

The international standard for the measurement of atomic masses. 1 carbon-12 = 12u

Question 8

What is relative isotopic mass?

Answer 8

The mass of an atom of an isotope relative to 1/12th of the mass of an atom of carbon-12

Question 9

What is relative atomic mass?

Answer 9

The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12.

Question 10

What 2 things does the weighted mean mass take into account?

Answer 10

Percentage abundance and relative isotopic mass.

Question 11

How are the percentage abundance of isotopes in a sample found?

Answer 11

Experimentally using a mass spectrometer.

Question 12

Method of using a mass spectrometer to determine percentage abundance:

Answer 12

1. A sample is placed in MS
2. Vaporised and ionised to form cations.
3. Ions are accelerated. Heavier ions separate from lighter as slower
4. Ions are detected on mass spectrum as a m/z.
5. The larger the abundance, the larger the signal

Question 13

What 2 things can a mass spectrometer record?

Answer 13

1. Percentage abundance of isotopes in a sample.
2. Mass to charge ratios of isotopes.

Question 14

What are binary compounds?

Answer 14

Contain two elements only e.g. H2O

Question 15

What are polyatomic ions?

Answer 15

Atoms of more than one element bonded together e.g. NH4+

Question 16

What is amount of substance, n?

Answer 16

Quantity used to count the number of particles in a substance in moles.

Question 17

How many atoms are in 12g of carbon-12?

Answer 17

6.02 x 10^23

Question 18

What is molar mass?

Answer 18

The mass per mole of a substance. Measured in g mol-1

Question 19

What is a molecule?

Answer 19

Two or more atoms held together by covalent bonds.

Question 20

What is molecular formula?

Answer 20

The number of atoms of each element in a molecule.

Question 21

What is empirical formula?

Answer 21

The simplest whole-number ratio of atoms of each element in a compound.

Question 22

Why is the empirical formula important?

Answer 22

Some substances don’t exist as molecules, so the empirical formula is useful for substances that form giant crystalline structures.

Question 23

What is relative molecular mass?

Answer 23

The weighted mean mass of a molecule with the mass of an atom of carbon-12.

Question 24

What is relative formula mass?

Answer 24

The mass of a formula unit compared with the mass of an atom of carbon-12.

Question 25

What is water of crystallisation?

Answer 25

Water molecules part of a crystalline structure.

Question 26

Method to determine the water of crystallisation in hydrated salts:

Answer 26

1. weigh empty crucible. 2. Add hydrated salt, reweigh. 3. Use pipe clay triangle to support crucible on tripod. 4. Heat gently for 1 min then strongly for 3 mins. 5. Leave crucible to cool 6. Weigh crucible and anhydrous salt.

Question 27

Assumptions when making an anhydrous salt:

Answer 27

1. All water has been lost. 2. Hasn't begun to decompose after heating.

Question 28

What is concentration?

Answer 28

The amount of solute dissolved in 1dm3 of solution.

Question 29

What is a standard solution?

Answer 29

A solution of known concentration.

Question 30

How is a standard solution made?

Answer 30

Dissolving an exact mass of solute in a solvent and making up solution to an exact volume.

Question 31

What 2 things influence the volume of a gas?

Answer 31

Temperature and pressure.

Question 32

What is molar gas volume?

Answer 32

the volume per mole of gas molecules at stated temperature and pressure.

Question 33

What is RTP?

Answer 33

20'C and 101kPa / 1atm

Question 34

What is the molar gas volume at RTP?

Answer 34

24.0 dm^3 mol-1

Question 35

Equation linking amount, volume and molar gas volume:

Answer 35

n = V / Vm

Question 36

What is the ideal gas equation?

Answer 36

PV = nRT

Question 37

What is 0 Kelvin in Celsius?

Answer 37

-273'C

Question 38

What is the value of constant R?

Answer 38

8.314 J mol-1 K-1

Question 39

What are 2 key assumptions of the ideal gas equation?

Answer 39

1. Forces between molecules are negligible. 2. Gas molecules have negligible size compared to the size of their container.

Question 40

Method to find a relative molecular mass using the ideal gas equation:

Answer 40

1. Add sample of volatile liquid to small syringe with a needle. 2. Weigh syringe. 3. Inject sample into gas syringe. 4. Reweigh small syringe 5. Place gas syringe in boiling water bath. 6. Record pressure. 7. pv=nrt to calculate unknown 8. n=m/M to find molar mass

Question 41

How is the real gas equation different to the ideal gas equation?

Answer 41

Takes the volume of gas molecules and inter molecular forces into account.

Question 42

What is the stoichiometry of a reaction?

Answer 42

The ratio of the amount of each substance in a balanced equation.

Question 43

Method to identify an unknown metal:

Answer 43

1. Attach gas syringe to conical flask. 2. Weigh sample of metal and add to flask. 3. Add excess HCl to the flask and replace bung. 4. Measure max volume of gas in the syringe.

Question 44

What are 3 reasons to explain why it is difficult to achieve theoretical yield?

Answer 44

1. Reaction may not go to completion. 2. Side reactions. 3. Purification may lose some mass.

Question 45

What is percentage yield?

Answer 45

The conversion of starting materials into desired product.

Question 46

What is atom economy?

Answer 46

A measure of how well atoms have been utilised.

Question 47

Benefits of improving atom economy:

Answer 47

Industrial processes are more efficient, preserves raw materials, reduces waste.

Question 48

What does the atom economy equation assume?

Answer 48

A 100% yield.