1.
State what is meant by relative atomic mass.
[1 mark]
- weighted mean mass of atoms vs 1/12 of C-12
JD SCIENCE
Module 2 Foundations in chemistry
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by the ideal gas equation.
[1 mark]
- pV = nRT
3.
State what is meant by empirical formula.
[1 mark]
- simplest ratio
4.
State what is meant by a mole.
[1 mark]
- 6.02 × 10²³ entities
5.
State what is meant by ionic bonding.
[1 mark]
- electrostatic attraction of ions
6.
State what is meant by covalent bonding.
[1 mark]
- shared electron pair
7.
State what is meant by electronegativity.
[1 mark]
- ability to attract a bonding pair
8.
State what is meant by metallic bonding.
[1 mark]
- cations + delocalised electrons
9.
State what is meant by a mass spectrum.
[1 mark]
- m/z of ions
10.
State what is meant by electron pair repulsion.
[1 mark]
- pairs repel, shape from number of pairs
11.
Grace is asked about relative atomic mass in a OCR Chemistry paper.
(a) [2 marks]
- from mass spectrometry
(b) [3 marks]
- isotopes
12.
Grace is asked about the ideal gas equation in a OCR Chemistry paper.
(a) [2 marks]
- SI units
(b) [3 marks]
- T in kelvin
13.
Grace is asked about empirical formula in a OCR Chemistry paper.
(a) [2 marks]
- from masses or %
(b) [3 marks]
- molecular formula needs Mr
14.
Grace is asked about a mole in a OCR Chemistry paper.
(a) [2 marks]
- n = m/M
(b) [3 marks]
- also n = cV
15.
Grace is asked about ionic bonding in a OCR Chemistry paper.
(a) [2 marks]
- giant lattice
(b) [3 marks]
- high MP, conduct when molten
16.
Grace is asked about covalent bonding in a OCR Chemistry paper.
(a) [2 marks]
- dative covalent possible
(b) [3 marks]
- shapes from electron pairs
17.
n in 8.0 g NaOH (M=40)
[3 marks]
- Final answer: 0.20 mol
18.
c if 0.025 mol in 250 cm³
[3 marks]
- Final answer: 0.10 mol dm⁻³
19.
pV=nRT: n=1, T=300, p=100 kPa. V
[3 marks]
- Final answer: 0.0249 m³ (R=8.31)
20.
% of C in C₂H₆ (M=30)
[3 marks]
- Final answer: 80%
21.
Mr from 12% of a 2+ ion at m/z 24. Actual Mr of atom
[3 marks]
- Final answer: 48 if that peak is the ion — treat as Mg²⁺ example: 24
22.
Bond angle in CH₄
[3 marks]
- Final answer: 109.5°
23.
Grace carries out a OCR-style required practical linked to atomic structure, amount of substance and bonding. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Grace carries out collecting valid data for atomic structure, amount of substance and bonding. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Grace carries out drawing a graph for atomic structure, amount of substance and bonding. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Grace carries out evaluating a method about atomic structure, amount of substance and bonding. This is a typical OCR required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare relative atomic mass with the ideal gas equation.
[4 marks]
- weighted mean mass of atoms vs 1/12 of C-12
- pV = nRT
- give one linked difference
28.
Compare the ideal gas equation with empirical formula.
[4 marks]
- pV = nRT
- simplest ratio
- give one linked difference
29.
Compare empirical formula with a mole.
[4 marks]
- simplest ratio
- 6.02 × 10²³ entities
- give one linked difference
30.
Compare a mole with ionic bonding.
[4 marks]
- 6.02 × 10²³ entities
- electrostatic attraction of ions
- give one linked difference
31.
Apply your knowledge of electronegativity to this situation: polar bonds if different
[3 marks]
- polar bonds if different
32.
Apply your knowledge of metallic bonding to this situation: malleable, conduct
[3 marks]
- malleable, conduct