WA 1 Dearing

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Thomas Edison State College *

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Chemistry

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Apr 3, 2024

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Name: Eric Dearing College ID: 0550796 Thomas Edison State College General Chemistry I with Labs (CHE-121) Section no.: Semester and year: May 2014 Written Assignment 1: Introduction and Measurement Answer all assigned questions and problems, and show all work. 1. Do the following statements describe chemical or physical properties? (10 points) a. Oxygen gas supports combustion. - Chemical b. Fertilizers help to increase agricultural production. - Chemical c. Water boils below 100°C on top of a mountain. - Physical d. Lead is denser than aluminum. - Physical e. Uranium is a radioactive element. - Physical (Reference: Chang 1.11) 2. Classify each of the following as an element, a compound, a homogeneous mixture, or a heterogeneous mixture: (7 points) a. water from a well - Compound b. argon gas - Element c. sucrose - Compound d. air – Homogenous mixture e. dirt – Heterogeneous Mixture f. a rusty iron nail - Heterogeneous g. ozone - Compound 3. Express the answers to the following calculations in scientific notation: (12 points) a. 145.75 + (2.3 × 10 –1 ) = 145.98, 2.3 x 10 –1 = 0.23, 145.75 + 0.23 = 145.98 b. 79,500 ÷ (2.5 × 10 2 ) = 318, 2.5 × 10 2 = 250, 79,500 ÷ 250 = 318 c. (7.0 × 10 –3 ) – (8.0 × 10 –4 ) = 7.0 x 10 –3 – 0.8 × 10 –3 = 6.2 x 10 –3 = 0.0062 d. (1.0 × 10 4 ) × (9.9 × 10 6 ) = (1.0 × 9.9) = (1.0 × 9.9)(10 4+6 = 10 10 ) = 9.9 x 10 10 =99,000,000,000 (Reference: Chang 1.31) 1
4. What is the number of significant figures in each of the following measurements? (8 points) a. 4867 mi, 4 significant figures b. 56 mL, 2 significant figures c. 60,104 ton, 5 significant figures d. 2900 g, ambiguous case, number may contain 4 (2.900x10 3 ), 3 (2.90x10 3 ), 2 (2.9x10 3 ) e. 40.2 g/cm 3 , 3 significant figures f. 0.0000003 cm, 1 significant figures g. 0.7 min, 1 significant figures h. 4.6 × 10 19 atoms, 2 significant figures (Reference: Chang 1.33) 5. Express the results in the proper number of significant figures. (12 points) a. 5.6792 m + 0.6 m + 4.33 m 5.6792 m + 0.6 m = 6.2792 m + 4.33 = 10.6, 3 significant figures b. 3.70 g – 2.9133 g = 0.79 g, 2 significant figures c. 4.51 cm × 3.6666 cm = 16.54 cm, 4 significant figures d. (3 × 10 4 g + 6.827g)/(0.043 cm 3 – 0.021 cm 3 ), 1g = 1 cm 3 30,000 g + 6.827 g =30,006.827 g 0.043 cm 3 – 0.021 cm 3 = 0.022 cm 3 6.827 ÷ 0.022 = 310.318 g, 6 significant figures (Reference: Chang 1.35) 6. Carry out the following conversions: (16 points) a. 22.6 m to dm, 1m=10dm, 22.6x10= 226 dm b. 25.4 mg to kilograms, 1 million mg = 1 kg - or - 1 kg = 1.0 x 10 -6 25.4 mg x 10 -6 = 2.54x10 -5 kg or 0.0000254 kg c. 556 mL to liters = 1000 ml = 1 liter, 556 ÷ 1000 = .556 liters d. 10.6 kg/m 3 to g/cm 3, , 1000 kg/m 3 = 1 g/cm 3 , 10.6 ÷ 1000 = 0.0106 g/cm 3 (Reference: Chang 1.39) 7. The average speed of helium at 25°C is 1255 m/s. Convert this speed to miles per hour (mph). (4 points) 1255 x 3600 (seconds in hour) = 4,518,000 ÷ 1609.344 (1 mile = 1609.344 meters) 2807.355047 mph or 2807.4 mph (Reference: Chang 1.41) 2
8. How many minutes does it take light from the sun to reach Earth? (The distance from the sun to Earth is 93 million miles; the speed of light is 3.00 × 10 8 m/s) (4 points) Convert miles to meters 9.3x10 7 x 1.61 = 149,730,000x10 8 or round up 1.50x10 8 Convert m/s to m/min 3.00x10 8 x60 seconds = 1.8x10 10 / m/hr/60 = 3.00x10 6 Convert m/hr to km/hr, 3.00x10 6 / 1000 = 300,000 R=D/T, D = 1.50x10 8 / T = 300,000 km/hr = 500 seconds / 60 = 8.33 minutes or 8min 20 sec (Reference: Chang 1.43) 9. Normal body temperature is 78.0°F. Calculate this temperature in degrees Celsius and Kelvin. (4 points) (78F-32F)=46F X 5C/9C=230/9=25.55555556 or 25.5C K = (25.5C + 273.15C) = 298.65K 10. Bromine is a reddish-brown liquid. Calculate its density (in g/mL) if 586 g of the substance occupies 188 mL. (4 points) d=m/V, density g/ml = 586 g / 188 ml = 3.12 g/ml is the density of Bromine. (Reference: Chang 1.21) 11. Aluminum is a lightweight metal (density = 2.70 g/cm 3 ) used in aircraft construction, high-voltage transmission lines, beverage cans, and foils. What is its density in kg/m 3 ? (4 points) 1000 kg in 1g/cm 3 , 2.70 g/cm 3 1000 = 2700 kg/m 3 12. Calculate the mass of a cube of platinum of edge length 0.040 mm (the density of platinum = 21.4 g/cm 3 ). (5 points) m=d x V, V = 0.040mm = 0.004cm, 0.004 3 = V 6.4x10 -8 d 21.4 g/cm 3 x V 6.4x10 -8 = 1.37x10 -6 (Reference: Chang 1.57) 13. A piece of silver (Ag) metal weighing 194.3 g is placed in a graduated cylinder containing 242.0 mL of water. The volume of water now reads 260.5 mL. From these data calculate the density of silver in units of g/mL. (5 points) d=m/V, 260.5ml-242mL = 18.5mL, m 194.3g / V 18.5 = 10.5 g/mL (Reference: Chang 1.61) 14. Cholesterol in blood is measured in milligrams of cholesterol per deciliter of blood. If the average adult has 6.0 liters of blood, how many grams of cholesterol would be in the blood of an average adult with a cholesterol reading of 185 mg/dL? Density of blood = 1.020 g/mL. (5 points) 1L = 10 dl, 6.0L = 60dL x185 mg/dL = 11,100 mg/dL / 1000 = 11.1g of cholesterol 3
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