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CHEM 145 Lab 2 Worksheet |
3

Lab 2 Worksheet

Student Name:

Date:

GRADE ____ /25 p

All work must be
very neat and
organized. If you need to collect your thoughts, please use a separate sheet of paper.

1. Express the following numbers in scientific notation.

a. 827

b. 450020

c. 0.000243

d. -91.123

2. Determine the number of significant figures in the following numbers.

a. 6.12

b. 4.009

c. 10082.3

d. 0.0001190

3. Perform the following calculations, and report your answer to the correct number of significant figures.

a. 2.45 + 18.920

b. 4.009 + 0.0024 – 2.12

c. 1.0042 0.00621

d.

4. Rewrite each quantity below using the commonly accepted symbols for each unit. (Example: 45 Joules = “45 J”)

a. 35 milliliters

b. 150 micrograms

c. 45.92 grams

d. 720 microliters

5. Using dimensional analysis, evaluate the following and report in the unit required. You may use the conversion factors provided.

a. 42.55 inches (report in centimeters; 1 in = 2.54 cm)

b. 159 milliliters (report in liters; 1 L = 1000 mL)

c. 0.0454 grams (report in milligrams; 1 g = 1000 mg)

d. 0.360 milliliters (report in microliters; 1 mL = 1000 μL)

6. Using dimensional analysis, evaluate the following and report in the unit required. Be sure to use the correct number of significant figures.

a. 0.735 mL + 1.10 mL (report in L)

b. 10.2 mL + 5.10 x L – 875 μL (report in mL)

c. 0.050 g + 8.0 mg – 3.112 x kg (report in g)

d. 8.0 mg – 3.11 x kg + 4598 μg (report in mg)

7. Using an electronic balance, 10.00 mL of methanol is found to have a mass of 7.911 g at room temperature. Calculate the density of methanol in g/mL at room temperature. Report your answer to the correct number of significant figures.

8. Toluene has a density of 0.865 g/mL at room temperature. Calculate the mass, in grams, of 500 mL of toluene at room temperature. Report your answer to the correct number of significant figures.

9. Caffeine has a molar mass of 194.19 g/mol. Calculate the mass, in grams, of 0.450 moles of caffeine. Report your answer to the correct number of significant figures.

10. Potassium chloride (KCl) has a molar mass of 74.551 g/mol. Calculate the mass in grams of KCl required to prepare 50.00 mL of a 0.300 mol/L aqueous solution of KCl. Report your answer to the correct number of significant figures.