Chem Review

Multiple Choice Identify the choice that best completes the statement or answers the question.

____ 1. Ice floats on water because a. of cohesion. c. water shrinks when it freezes. b. ice has a higher density than water. d. water expands when it freezes. ____ 2. Which of the following does NOT describe a polymer? a. Polymers are made of monomers. b. Polymers are large molecules. c. Polymers usually form by covalent bonding. d. Polymers are broken down by the process of hydrogenation. ____ 3. What are the basic building blocks of proteins? a. nucleic acids c. amino acids b. peptide bonds d. glycerol and fatty acids ____ 4. Water dissolves many ionic and molecular compounds because of its _____. a. ionic bonding c. covalent bonding b. polarity d. hydrogen bonding ____ 5. The various enzymes in our bodies are _____. a. lipids c. nucleotides b. carbohydrates d. proteins ____ 6. A very strong base might have a pH of _____. a. 3 c. 9 b. 5 d. 13 ____ 7. Carbon-12, carbon-13, and carbon-14 are _____. a. isotopes c. radioisotopes b. polymers d. macromolecules ____ 8. An unsaturated lipid contains _____. a. more oxygen than hydrogen c. ionic bonds b. double bonds d. only one fatty acid ____ 9. Unlike carbohydrates and fats, proteins contain _____. a. nitrogen c. hydrogen b. carbon d. oxygen ____ 10. Which element would need to be removed from the molecule in Figure 6-5 to make it unsaturated?

Figure 6-5 a. carbon c. oxygen b. hydrogen d. phosphorus

Completion Complete each statement.

11. Due to ______forces, the design of a gecko’s feet enables it to climb up vertical surfaces. 12. The pH scale is a measurement system that indicates the concentration of ______in solution. 13. Chemical reactions that ______energy will not occur without a source of energy. 14. An organic compound with a ratio of about two hydrogen atoms and one oxygen atom for each carbon atom is a(n) ______. 15. The smaller subunits that make up nucleic acids are ______. 16. Any substance that forms hydrogen ions in water is a(n) ______. 17. Two atoms that share electrons are held together by ______bonds. 18. Atoms of two or more elements chemically combined are ______. 19. Atoms of the same element with different numbers of neutrons are ______. 20. Because they have the same number of protons and electrons, all isotopes of an element have the same ______properties. 21. A chemical bond formed by the transfer of electrons is a(an) ______bond. 22. A water molecule is polar because there is an uneven distribution of electrons between the oxygen and ______atoms.

Short Answer

23. What is mass number? 24. What accounts for water’s properties of adhesion and cohesion? 25. Use the terms solvent and solute in describing how to prepare a salt solution. 26. Distinguish between RNA and DNA. 27. Name two essential roles that enzymes play in cells. 28. Explain the importance of carbon's ability to form covalent bonds in straight chains, branched chains, or rings. 29. What is a molecule? 30. What are the main types of chemical bonds? 31. What are the four groups of organic compounds found in living things?

Essay

32. What relationship exists between the mass number of an element and the isotopes of that element? 33. Explain the difference between ionic compounds and covalently bonded compounds. 34. Compare and contrast adhesion and cohesion, using capillary action as an example. 35. Compare enzyme activity to a lock and key. USING SCIENCE SKILLS

pH Values of Some Common Substances Substance pH Hydrochloric acid 1.0 Sulfuric acid 1.2 Tomatoes 4.2 Rainwater 6.2 Pure water 7.0 Sea water 8.5 Ammonium chloride 11.1 Sodium hydroxide 13.0

Figure 2–1

36. Applying Concepts What is the strongest acid listed in Figure 2-1? 37. Applying Concepts What is the pH of the weakest acid listed in Figure 2-1? 38. Applying Concepts What is the pH of the strongest base listed in Figure 2-1? 39. Applying Concepts According to the pH values of Figure 2-1, does a solution with a hydrogen ion concentration less than that of pure water have a pH greater or less than 7? 40. Calculating A change of one unit on the pH scale represents a tenfold increase in the concentration of hydrogen ions. According to the pH values listed in Figure 2-1, how much greater is the hydrogen ion concentration in tomatoes than in rainwater?