3.4. Classify each of the following pure substances as either an element or a compound.

Transcription

1 CH 112 Chapter 3 Homework Key (Due 4/17/2018) 3.4. Classify each of the followin pure substances as either an element or a compound. a. Helium as (He) element b. Mercury (H) in a thermometer element c. Suar (C 12H 22O 11) compound d. Sulfur (S) element e. Lye (NaOH) compound 3.6. Classify each of the followin mixtures as homoeneous or heteroeneous. a. Nonfat milk Either. Nonfat milk is sometimes referred to a homoenized milk, but lobules of protein may be present, leadin to a heteroeneous mixture. b. Chocolate-chip ice cream Heteroeneous c. Gasoline Homoeneous d. Peanut butter sandwich Heteroeneous e. Cranberry juice Homoeneous Describe each of the followin as a chemical or physical property. a. Neon is a colorless as at room temperature Physical b. Apple slices turn brown when exposed to air Chemical c. Phosphorus will inite in air Chemical d. Mercury is a liquid at room temperature Physical e. Propane as is compressed to a liquid for storae Physical Describe each property of the element zirconium as physical or chemical. a. Melts at 1852 C Physical b. Is resistant to corrosion Chemical c. Has a rayish-white color Physical d. Inites spontaneously in air Chemical

2 e. Is a shiny metal Physical Calculate the unknown temperature in each of the followin: a. 25 C = 77 F b. 155 C = 311 F c. 25 F = - 32 C d. 224 K = - 49 C e. 145 C = 418 K **Remember, you need to know the formulas to do these conversions for Exam 1** Indicate whether each of the followin describes potential or kinetic enery: a. The enery in your food Potential (from chemical enery) b. A tihtly wound sprin Potential (from position) c. An earthquake Kinetic (associated with motion) d. A car speedin down the road Kinetic (associated with motion) Usin the enery values for foods (table 3.7), determine each of the followin (round off the answers in kcal or k to the tens place). a. The total k in two tablespoons of crunchy peanut butter than contains 6 carbohydrate, 16 fat, and 7 protein: 17 k 38 k 17 k (6 carbohydrate ) + (16 fat ) + (7 protein ) = 829 k = 830 k b. The rams of protein in 1 cup of soup with 110 kcal that contains 9 carbohydrate and 6 fat. (9 carbohydrate 4 kcal ) + (6 fat 9 kcal ) + (X protein 4 kcal ) = 110 kcal Solve for X to find there should be 5 of protein. c. The kcal in one can of cola if it has 40. of carbohydrate and no fat or protein. (40 carbohydrate 4 kcal ) = 160 kcal

3 d. The total kcal for a diet that consists of 68 carbohydrate, 9 of fat, and 150 protein. (68 carbohydrate 4 kcal ) + (9 fat 9 kcal ) + (150 protein 4 kcal ) = 953 kcal = 950 kcal For lunch, a patient consumed 3 oz of skinless chicken, 3 oz of broccoli, 1 medium apple, and 1 cup of nonfat milk (see table 3.8). How many kcal did the patient obtain from lunch? (110 kcal chicken) + (30 kcal broccoli) + (60 kcal apple) + (90 kcal milk) = 290 kcal Use the heat equation to calculate the enery (in and cal) for each of the followin: a. To heat 5.25 of water from 5.5 C to 64.8 C. (5.25 water) (4.184 ) ( ) = 1300 (5.25 water) (1.00 cal ) ( ) = 310 cal b. Lost when 75.0 of water cools from 86.4 C to 2.1 C. (75.0 water) (4.184 ) ( ) = (75.0 water) (1.00 cal ) ( ) = 6300 cal **The minus sin indicates that the heat is leavin the system, i.e., the water** c. To heat 10.0 of silver from 112 C to 275 C. (10.0 silver) (0.235 ) ( ) = 383 (10.0 silver) ( cal ) ( ) = 91.6 cal

4 d. Lost when 18.0 of old cools from 224 C to 118 C. (18.0 old) (0.129 ) ( ) = 246 (18.0 old) ( cal ) ( ) = 58.8 cal Identify each of the followin chanes of state as meltin, freezin, sublimation, or deposition. a. Dry ice in an ice-cream cart disappears. Solid as. Sublimation. b. Snow on the round turns to liquid water. Solid liquid. Meltin. c. Heat is removed from 125 of water at 0 de C Liquid solid. Freezin. d. Frost forms on the walls of a freezer. Gas solid. Deposition (see pae 85) Calculate the heat chane at 100 C for each of the followin and indicate whether heat was absorbed or released. **Use the heat of vaporization conversion!** a. calories to condense 10.0 of steam. Condense means as liquid, use heat of vaporization. Heat is lost from the system steam * 540 cal/ steam = 5400 cal (heat lost) b. joules to condense 7.60 of steam. Heat is lost steam *2260 / steam = (heat lost, 3 si fis) c. kilocalories to vaporize 44 of water Heat absorbed for vaporization. 44 water*540 cal/ water*1 kcal/1000 cal= kcal 24 kcal (2 si fis) d. kilojoules to vaporize 5.00 k of water. Heat is absorbed k * 1000 /k * 2260 / * 1 k/1000 = k (3 si fis) Draw a coolin curve for a sample of steam that cools from 110 de C to -10 de C. Indicate the sement of the raph that corresponds to each of the followin: a. solid b. freezin c. liquid d. condensation e. as

5 3.52. Usin the values for the heat of fusion, specific heat of water, and/or vaporization, calculate the amount of heat enery in each of the followin: a. released when 125 of steam at 100 C condenses and cools to a liquid at 15.0 C. Step 1: Condensation from as to liquid. 125 *2260 / = Step 2: Cool the liquid water. 125 * 4.18 / C * 85 C = Step 3: Sum the two steps, round: round to 1 si fi (100 C) b. kcal needed to melt a 525 ice sculpture at 0 C and warm the water to 15.0 C. Step 1: Meltin the solid to liquid. 525 * 80. cal/ = cal Step 2: Warm the water. 525 * 1.00 cal/ C * 15 C = 7875 cal Step 3: Sum, round, convert unit cal cal 50. kcal c. k released when 85.0 of steam condenses at 100 C, cools, and freezes at 0 C. Step 1: Condense from as to liquid * 2260 / = Step 2: Cool the water: 85.0 * 4.18 / C * 100 C = Step 3: Freeze liquid to solid: 85.0 * 334 / = Step 4: Sum all steps, round, convert units: k

6 3.102*. A 125 piece of metal is heated to 288 C and dropped into 85.0 of water at 12.0 C. The metal and the water come to the same temperature of 24.0 C. What is the specific heat (in / C) of the metal? heat lost by metal = heat ained by water (125 )(Cs)(264 C) = (85.0 )(4.18 / C)(12 C) Cs metal = / C (The metal is old)