CHE-121 Written Assignment 1 WA1 PDF

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Written Assignment 1 questions, answers, and work....

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Name: College ID: Thomas Edison State University General Chemistry I with Labs (CHE-121) Section no.: 1 Semester and year: MAR2018

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. i. Chemical Property b. Fertilizers help to increase agricultural production. i. Chemical Property c. Water boils below 100°C on top of a mountain. i. Physical Property d. Lead is denser than aluminum. i. Physical Property e. Uranium is a radioactive element. i. Chemical Property (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. b. c. d. e. f. g.

water from a well argon gas sucrose air dirt a rusty iron nail ozone

Compound Element Compound Element Heterogeneous mixture Heterogeneous mixture Element

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3. Express the answers to the following calculations in scientific notation: (12 points) a. b. c. d.

145.75 + (2.3 × 10 –1) 79,500 ÷ (2.5 × 102) (7.0 × 10–3) – (8.0 × 10–4) (1.0 × 104) × (9.9 × 106)

= 1.4598 * 10^2 = 3.18 * 10^-2 = 6.2 * 10^-3 = 9.9 * 10^10 (Reference: Chang 1.31)

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 =4 significant figures e. 40.2 g/cm3 =3 significant figures f. 0.0000003 cm =1 significant figures g. 0.7 min =1 significant figures h. 4.6 × 1019 atoms =2 significant figures (Reference: Chang 1.33)

5. Express the results in the proper number of significant figures. (12 points) a. b. c. d.

5.6792 m + 0.6 m + 4.33 m =10.6 3.70 g – 2.9133 g =0.79 4.51 cm × 3.6666 cm =16.5cm (3 × 104g + 6.827g)/(0.043 cm3 – 0.021 cm3)=1 *10^6 g/cm (Reference: Chang 1.35)

6. Carry out the following conversions: (16 points) a. b. c. d.

22.6 m to dm 25.4 mg to kilograms 556 mL to liters 10.6 kg/m3 to g/cm3

=22.6 dm =2.54e-5 kg or 0.0000254 kg =0.556 L =0.0106g/cm^3 (Reference: Chang 1.39)

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7. The average speed of helium at 25°C is 1255 m/s. Convert this speed to miles per hour (mph). (4 points) (Reference: Chang 1.41)

2.23694 * 1255=2807.35 MPH

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 × 108 m/s) (4 points) (Reference: Chang 1.43)

1 mile= 1609.34 meters 93,000,000 * 1609.34= 149,668,620,000 meters 3.00 * 10^8m/s= 300,000,000 m/s 149,668,620,000/300,000,000=498.8954 seconds 498.8954seconds/60 seconds per minute= 8.315 minutes 9. Normal body temperature is 78.0°F. Calculate this temperature in degrees Celsius and Kelvin. (4 points) 78-32=46 /1.8=25.5C 25.5+273=298.5K 10. Bromine is a reddish-brown liquid. Calculate its density (in g/mL) if 586 g of the substance occupies 188 mL. (4 points) (Reference: Chang 1.21)

Density= 586/188= 3.12g/ml 11. Aluminum is a lightweight metal (density = 2.70 g/cm3) used in aircraft construction, high-voltage transmission lines, beverage cans, and foils. What is its density in kg/m3? (4 points) (Reference: Chang 1.51) Density=2700kg/m3 12. Calculate the mass of a cube of platinum of edge length 0.040 mm (the density of platinum = 21.4 g/cm3). (5 points) (Reference: Chang 1.57)

Mass=6.4x10^-8cm^3 * 21.4g/cm^3= 1.4 *10^-6g 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) (Reference: Chang 1.61)

60.5-240=20.5ml=Vol. 194.3g= Mass 194.3/20.5=9.48g/ml 3 Copyright © 2017 by Thomas Edison State University. All rights reserved.

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) 1850mg/dL * 6L= 11,100mg/1000=11.1g of cholesterol.

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