Sample Assessment Schedule 2012

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NCEA Level 2 Chemistry 91165 (2.5) — page 2 of 6 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). C 2 H 4 Cl 2 has two structural isomers, one has a condensed structural formula CH 2 Cl–CH 2 Cl and the other CH 3 –CHCl 2 C 2 H 2 Cl 2 also has structural isomers, one has a condensed structural formula CH 2 Cl–CHCl and the other CH 2 –CCl 2 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. C 2 H 4 Cl 2 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 C 2 H 4 Cl 2 cannot form geometric isomers. C 2 H 2 Cl 2 has a double bond and each carbon involved has two different groups attached to them so C 2 H 2 Cl 2 can form geometric isomers.
NCEA Level 2 Chemistry 91165 (2.5) — page 3 of 6 NØ N1 N2 A3 A4 M5 M6 E7 E8 No response or does not address the question. Provides some writing but does not fulfil any statement from the Achievement criteria column. Any ONE statement from the Achievement criteria column. Any TWO statements from the Achievement criteria column. Any THREE statements from the Achievement criteria column. Any ONE statements from the Merit criteria column. Gives BOTH statements from the Merit criteria column. Only minor error – omission or additional information – from the Excellence criteria column. All the evidence from the Excellence criteria column. Two Expected Coverage Achievement Merit Excellence (a) See Appendix One. THREE of the (b) Water following: 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 - CH 3 COOH + H 2 O CH 3 COO – + H 3 O + 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.
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Sample Assessment Schedule 2012

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