SAMPLE ASSESSMENT SCHEDULE
Chemistry 91165 (2.5): Demonstrate understanding of the properties of selected organic compounds
Assessment Criteria
Achievement Achievement with Merit Achievement with Excellence
Demonstrate understanding involves naming and drawing structural formulae of selected organic compounds (no more than eight carbons in the longest chain) and giving an account of their chemical and physical properties. This requires the use of chemistry vocabulary, symbols and conventions.
Demonstrate in-depth understanding involves making and explaining links between structure, functional groups and the chemical properties of selected organic compounds. This requires explanations that use chemistry vocabulary, symbols and conventions.
Demonstrate comprehensive understanding involves elaborating, justifying, relating, evaluating, comparing and contrasting, or using links between the structure, functional groups and the chemical
properties of selected organic compounds. This requires the consistent use of chemistry vocabulary, symbols and conventions.
Evidence Statement
One Expected Coverage Achievement Merit Excellence
(a) Monomer is: THREE of
following:
• in (a) structure of monomer correct
• in (b) BOTH structures correct
• in (c) BOTH isomers drawn correctly in correct box
• in (d) structural or geometric isomers described
• in (d) structural isomers for C2H4Cl2 drawn.
• In (d) structural isomers linked to both C2H4Cl2
and to C2H2Cl2
OR
• in (d) geometric isomers linked to C2H2Cl2 and reasons why C2H4Cl2 does not have geometric isomers OR
• in (d) BOTH isomer types linked to either the chloroalkane or the
chloroalkene.
In (d)
requirements for both geometric and structural isomers linked to both molecules.
(b)
1, 2-dichloroethene
1, 1-dichloroethene (c) (i)
(ii)
1, 2-dichloroethene cis
trans
(d) Structural isomers are compounds with the same molecular formula (they have the same type and number of atoms) but different structural formulae (structures).
C2H4Cl2 has two structural isomers, one has a condensed structural formula CH2Cl–CH2Cl and the other CH3–CHCl2
C2H2Cl2also has structural isomers, one has a condensed structural formula CH2Cl–CHCl and the other CH2–CCl2
Geometric isomers are compounds with the same molecular formula, the same (condensed) structural formula but different arrangement of atoms. It occurs in molecules that have double bonds because the rotation of the atoms about the axis of the carbon to carbon double bond is restricted. They must also have two different groups attached to each end of the double bond.
C2H4Cl2 doesn’t have a double bond; it has a single bond between the carbon atoms. Rotation of the atoms about this bond can occur freely so C2H4Cl2 cannot form geometric isomers.
C2H2Cl2 has a double bond and each carbon involved has two different groups attached to them so C2H2Cl2 can form geometric isomers.
NØ No response or does not address the question.
N1 Provides some writing but does not fulfil any statement from the Achievement criteria column.
N2 Any ONE statement from the Achievement criteria column.
A3 Any TWO statements from the Achievement criteria column.
A4 Any THREE statements from the Achievement criteria column.
M5 Any ONE statements from the Merit criteria column.
M6 Gives BOTH statements from the Merit criteria column.
E7 Only minor error – omission or additional information – from the Excellence criteria column.
E8 All the evidence from the Excellence criteria column.
Two Expected Coverage Achievement Merit Excellence
(a) See Appendix One. THREE of the following:
• in (a) THREE names or structural formulae correct
• in (a) THREE homologous series identified or functional groups correct
• in (b) reaction with two of water, litmus or bromine water described with observations for one solution OR any two observations
• in (b) reaction with one of water, litmus or bromine water described with observations for three (different) solutions.
OR any one solution correctly identified
In (b) THREE solutions identified with all tests required to positively identify.
In (b) writes a valid method that distinguishes between the five solutions. At least two equations are included.
(b) Water
Add water to the five solutions. Three solutions will dissolve in water (ethanol, aminoethane, ethanoic acid), two will not (hexane, hex-1- ene).
Litmus
Use the solutions formed by
dissolving in water. Add both red and blue litmus paper to the solutions in water.
One will not change the colour of the litmus paper, this is ethanol.
One will turn blue litmus red, this is ethanoic acid.
One will turn red litmus blue, this is aminoethane.
Test the solutions which did not dissolve in water by reacting fresh solutions with bromine water. If the solution turns from brown to
colourless the solution is hex-1-ene.
Hexane will not react with the bromine water.
Equations with water -
CH3COOH + H2O CH3COO– + H3O+
CH3CH2NH2 + H2O CH3CH2NH3+
+ OH–
Equation with bromine water – CH3– CH2– CH2– CH2– CH=CH2 + Br2 CH3– CH2– CH2– CH2– CHBr– CH2Br
NØ No response or does not address the question.
N1 Provides some writing but does not fulfil any statement from the Achievement criteria column.
N2 Any ONE statement from the Achievement criteria column.
A3 Any TWO statements from the Achievement criteria column.
A4 Any THREE statements from the Achievement criteria column.
M5 TWO solutions identified with all tests to positively identify.
M6 Gives BOTH statements from the Merit criteria column.
E7 Only minor error – omission or additional information – from the Excellence criteria column.
E8 All the evidence from the Excellence criteria column.
Three Expected Coverage Achievement Merit Excellence
(a) Compound A is CH3–CH2–CH2–OH THREE of the following:
• in (a) compound A correct
• in (b) TWO out of FOUR compounds of reactants correct
• in (c)(i) TWO reaction types described but not linked to the atoms involved
• in (c) (ii) ONE reaction type described.
In (c) THREE reactions correct in terms of reactant, product and reaction type which is linked to a reason for the reaction type.
In (c) THREE reactions correct in terms of both reactant, product and reaction type AND the
justification of reaction type for that reaction.
(b) (i) (ii)
Compound B is CH3–CH2–CH2–NH2
Reactant P is HCI
Reactant Q is concentrated H2SO4
Reactant R is HCl (c) (i)
(ii)
(1) substitution.
(2) substitution.
(3) elimination.
(4) addition.
Molecules that undergo substitution reactions have carbon to carbon single bonds and form molecules with carbon to carbon single bonds. In a substitution reaction an atom or group of atoms is replaced by another atom or group of atoms.
Molecules that undergo elimination reactions have carbon to carbon single bonds and form molecules with carbon to carbon double bonds. In an
elimination reaction two atoms or small groups are removed from a molecule forming a carbon to carbon to double bond.
Molecules that undergo addition
reactions have carbon to carbon double bonds and form molecules with carbon to carbon single bonds. In an addition reaction the reaction involves breaking a double bond between the carbon atoms and forming a single bond in its place as well as forming two new single bonds.
Reactions (1) and (2) are both
substitution reactions as the molecules have carbon to carbon single bonds. In (1) the hydroxyl group (–OH) is
replaced by a chloro group (–Cl). In (2) the chloro group (–Cl) is replaced by the amine group (–NH2).
Reaction (3) is an elimination reaction as the molecule has carbon to carbon single bonds and a double bond is formed when it reacts. A hydrogen atom and the hydroxyl group on adjacent carbon atoms are removed forming a carbon to carbon double bond.
Reaction (4) is an addition reaction as the molecule has carbon to carbon double bonds and the product has carbon to carbon single bonds. In this reaction the double bond breaks forming a single bond, a hydrogen atom attaches itself to one of the carbon atoms and a chlorine atom attaches itself to the other carbon atom.
NØ No response or does not address the question.
N1 Provides some writing but does not fulfil any statement from the Achievement criteria column.
N2 Any ONE statement from the Achievement criteria column.
A3 Any TWO statements from the Achievement criteria column.
A4 Any THREE statements from the Achievement criteria column.
M5 TWO reactions correct in terms of reactant, product, reaction type, which is linked to a reason for the reaction type.
M6 THREE reactions correct in terms of reactant, product, reaction type, which is linked to a reason for the reaction type.
E7 Only minor error – omission or additional information – from the Excellence criteria column.
E8 All the evidence from the Excellence criteria column.
Appendix One: Question Two (a)
