EXAM PRACTICE QUESTIONS ANSWERS Chapter 13 1. A chemical reaction releases 58.5 kJ into 150. g of water. Assuming no heat is lost to the surroundings, what is the temperature increase of the water? The specific heat of water is 4.18 J/gqC. C 93.3 C)J/g (4.18 g 150J 58,500 gCQ T$$ ' 2. Arrange the following substances in order of increasing boiling point. Ne < H2Se < H2O < NaClO3 3. Consider the following compounds. CH3NH2, CH4, C2H6, SiH4, H2S a) Which compound would have the highest molar heat of vaporization? CH3NH2 b) Which compound(s) would exhibit London forces? CH4, C2H6, SiH4 c) Which compound(s) is the predominant intermolecular force dipole-dipole interactions? H2S d) Which compound would boil at the lowest temperature? CH4 e) Which compound(s) would exhibit hydrogen bonding? CH3NH2 4. How much heat is released when 40.0 g of steam at 250 qC cools and condenses to water at 30.0 qC? Specific Heat of water is 4.18 J/gqC, Specific Heat of steam is 2.03 J/gqC, heat of vaporization of water is 2.260 kJ/g J = 40.0 g (2.03 J/gqC) (150. qC) + 2260 J/g (40.0 g) + 40.0 g (4.18 J/gqC) (70.0 qC) J = 12200 J + 90400 J + 11700 J = 114,300 J5. What is the heat of fusion of chromium (in kJ/mol) if 10.0 grams of solid chromium absorbs 2.82 u 103 J of heat in melting at 2173 K, its melting point? kJ/mol 14.7 mol 0.192kJ 2.82 Cr mol 0.192 Cr g/mol 52.0Cr g 10.0 6. Arrange the following in order of increasing melting points. CsCl, BaCl2, Cdiamond, HF, H2 H2 < HF < CsCl < BaCl2 < Cdiamond 7. Arrange the following in order of increasing melting points. Al2O3, MgCl2, NaF NaF < Al2O3 < Al2O3 8. Indicate the type of solid (molecular, ionic, metallic, covalent) each of the following forms. sulfur dioxide molecular solid Cgraphite covalent solid calcium bromide ionic solid lithium metallic solid methane (CH4) molecular solid 9. The average specific heat of water is 4.18 J/g Û& If 905 J is added to 75 g of water at 23.9 Û& what is the final temperature of the water sample? C 2.9 C)J/g (4.18 g 75J 905 gCQ T$$ ' Since heated is added to the water, the initial temperature will increase. 23.9 Û& + 2.9 Û& = 26.8 Û&10. What is the predominate intermolecular force between the following pairs of molecules in solution? Draw Lewis structures of each molecule. Use a dashed line to represent the type of intermolecular force between the molecules. Use G+ and G- symbols to show the direction of polarity within bonds. A) LiCl and H2O ion-dipole Li+Cl-OHHOHHG+G+G-OHHG+G+OHHOHHG+G+G-G-G+G+G+G+G-G-OHHG+G+G- B) BeCl2 and C2H6 London forces G+G-Cl BeClCCHHHHHHCl Be ClCCHHHHHHorG-G-G+G-G-G+G+G- C) CH3COCH3 and HF hydrogen bonding G+G-HFCCHHHHHHG-G+COD) AsF3 and CHCl3 dipole-dipole interactions