homework

Medgar Evers College

Chemistry and Environmental Sciences CHM 105

Dr. Dereck Skeete Show all calculations

Name: __________________________

CLASS EXERCISE

1. Give each answer correct to the number of sig. figs.

(a) 8.185 × 0.49           

(b) 0.48 ÷ 0.0638

2. Round off each of the following to 3 significant figures.

(a) 12,345

(b) 1, 650,953

(c) 0.082055

(d) 95,000.

3. Determine the correct number of sig.fig.

(a) The beehive containing 13,000 bees

(b) A sheet of paper is 0.0042 inches thick

4. Round off to 2 significant figures

(a) 432,117

(b) 0.435

5. Let's round off 64,492 to:

(a) 1 significant figure     

(b) 2 significant figures    

(c) 3 significant figures    

(d) 4 significant figures    

6. Express the following scientific notation in decimal form

(a) 5.3246 x 104

(b) 1.63 x 10-7

(c) 4.2 x 10-2

(d) 3.0 x 108

7. The answer to the multiplication of 0.00278 x 30 reported to the correct number of significant figures is:

8. If you were given the following measurements, which of the following zeros would be significant:

20.05 g 5.00 m 0.00002 L 120000kg 8.05 x 102 g 1.005

9. Put these numbers in scientific notation:

0.00034 549 40,050,000

10. Take these numbers out of scientific notation and write them in decimal form.

9.481 x 10-8 3.64 x 104 3.92000 x 102

11. (a). A flask that weighs 635.8 g is filled with 225 mL of carbon tetrachloride. The weight of the flask and carbon tetrachloride is found to be 810.5 g. From this information, calculate the density of carbon tetrachloride.

(b). Calculate the density of sulfuric acid if 35.4 mL of the acid weighs 95.14 g.

(c). What volume of silver metal will weigh exactly 5.30 g. The density of silver is 10.5 g/cm3.

12. Please solve the following conversion problems. (show all the steps)

(a) 0.95 kg to milligrams

(c) 3390 g to kg

(d) 0.92 km to centimeters

13. An oven for baking pizza operates at approximately 525oF. What is the equivalent temperature on the Celsius scale?

14. A typical lightning bolt is approximately 30,000oC. What is the equivalent temperature in Fahrenheit and Kelvin?

15. The density of osmium (the densest metal) is 2260g/cm3. What is the mass in grams of a block of osmium with dimensions 5.00in x 4.00in x 0.25ft?