ACSBR 20B Molecular Structures (Extensions) - Assignment

Anglo-Chinese School (Barker Road) A Methodist Institution Founded in 1886 CHEMISTRY DEPARTMENT OF SCIENCE Name: ( ) Class: SEC 4 OC: MOLECULAR STRUCTURES (EXTENSIONS) – ASSIGNMENT ALEX LEE/2010 PAGE 1 OF 6 PURE Multiple-Choice Questions [20 Marks] TOTAL SCORE / 30 Write in your selected answer for the multiple-choice questions in the boxes provided. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1. Which of the following statements about isomers is false? A Isomers have the same relative molecular mass. B Isomers have the same strength of intermolecular forces. C Isomers may have the same chemical properties as each other. D Isomers have the same percentage composition of elements. 2. Two molecules are isomers. It follows that these two molecules A contain the same elements. C have different molecular formulae. B contain the same functional group. D have the same structural formula. 3. Butanoic acid has a formula C4H8O2. It can be concluded that an isomer of this molecule A must be able to react with carbonates. B must combust to form carbon dioxide and water. C must contain the –COOH functional group. D must not contain a C=C bond in its structure. 4. What property do methylpropane and butane not have in common? A combustion products B empirical formula C melting and boiling points D relative molecular mass 5. The smallest alkane to have more than one structural isomer is A butane B ethane C pentane D propane

ALEX LEE/2010 PAGE 2 OF 6 6. How many structural isomers exist for C2H6O? A one B two C three D four 7. Which of the following molecules have the greatest number of structural isomers? A C3H7Cl B C3H6Cl2 C C3H4Cl4 D C3H2Cl6 8. A compound with the formula C4H9F has A 2 isomers. B 3 isomers. C 4 isomers. D 5 isomers. 9. Which, of the four molecules below, is a different structure from the other three molecules? A C B D 10. Which of the following pairs of molecules are not isomers? A and B and C and D and C C Cl Cl H H H Cl C C H H Cl Cl Cl H C C Cl H Cl Cl H H C C H Cl Cl H Cl H C C C H Cl H Cl H H H H C C C H H Cl H H H Cl H C C C H H Cl H H Cl H H C C C H H H Cl H H Cl H C C C Cl H H Cl H H H H C C C H H Cl H Cl H H H C C C H H Cl Cl H H H H C C C Cl H Cl H H H H H

ALEX LEE/2010 PAGE 3 OF 6 11. Three molecules, X, Y and Z, are shown below. molecule X molecule Y molecule Z Which of the following statements are true? A Molecules X and Y have different molecular formula. B Molecules X and Z are isomers of each other. C Molecules X and Z have the same structural formula. D Molecules Y and Z have the same melting and boiling points. 12. The structure of a chloroalkane P is shown below. molecule P Which of the molecules below are identical to P? A C B D 13. Which of the following molecules only exist as one isomer? A C2H4F2 B C2H3F3 C C2H2F4 D C2HF5 C C Cl C H Cl H H H H C H H H C C H C Cl H H H H Cl C H H H C C H C H H H Cl Cl H C H H H C C Cl C H H H H H Cl C H H H C C Cl C H H H H H H C H H Cl C C H C H H H H H H C H H H C C H C H H H H H H C H H H C C H C H H H H H H C H H H

ALEX LEE/2010 PAGE 4 OF 6 14. Two molecules, pentene and cyclopentane, are shown below. pentene cyclopentane Which of the following statements about these two molecules are true? A Pentene and cyclopentane are isomers of each other. B Pentene and cyclopentane have the same chemical properties. C Pentene is a hydrocarbon while cyclopentane is not. D Pentene requires more oxygen for combustion compared to cyclopentane. 15. The diagrams below show five fluoroalkanes with the formula C5H11F. molecule 1 molecule 2 molecule 3 molecule 4 molecule 5 Which two molecules are the same? A molecules 1 and 2 C molecules 3 and 5 B molecules 2 and 4 D molecules 4 and 5 16. Which of the following molecules contain exactly three chlorine atoms? A 1,1,3,3-tetrachlorohexane C 1-chloro-3-fluorobutane B 1-bromo-1,1,2-trichloroethane D 2,3-dichloro-1,3-difluoropentane

ALEX LEE/2010 PAGE 5 OF 6 17. The structure of an organic molecule is shown below. Which of the following names best describe this molecule? A ethylbutane B ethylpentane C methylbutane D propylpropane 18. The structure of an organic molecule is shown below. A ethylbutane B ethylpropane C methylbutane D methylpropane 19. Which of the following molecules is 1,2,2-trichloropropane? A C B D 20. Which of the following pairs of molecules are isomers? A chloromethylpropane and dichloromethylpropane B dichlorobutane and dichloropropane C dimethylpropane and methylbutane D ethylbutane and methylpropane C C C H H H Cl H H Cl Cl C C C H Cl H H H Cl Cl H C C C Cl H Cl H H Cl H H C C C Cl H Cl Cl H H H H C C C H C H H H H H H H C H C H H H H C H H H H C C C H H H H C H H H H C H H H

ALEX LEE/2010 PAGE 6 OF 6 Structured Questions [10 Marks] 21. Ethane can undergo a chemical reaction with chlorine to form gaseous trichloroethane, C2H3Cl3, with hydrogen chloride as a byproduct. This product has two isomers. (a) Construct a chemical equation, including state symbols, for this reaction. [1] (b) Explain what is meant by the term ‘isomers’. [1] (c) In the space below, write down the names of the two isomers of trichloroethane and draw their full-structural formula. [4] Isomer #1 Isomer #2 Name: Name: Full Structural Formula: Full Structural Formula: (d) Propane can undergo a similar reaction with chlorine to form trichloropropane, C3H5Cl3. How many structural isomers does trichloropropane have? [1] 22. From the list of names provided below, identify the molecules shown. [3] 1-bromobutan-2-ol 2-bromopropanoic acid 3-methylbut-1-ene 1-methylpent-2-ene 1-bromobutan-2-ol butan-2-ol END