Chemistry 1. Worksheet 2. Units and Unit Conversions. 1 MathTutorDVD.com

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1 Chemistry 1 Worksheet 2 Units and Unit Conversions 1

2 1) Give the abbreviation for the following units. a. kilogram b. meter c. gram d. second e. Kelvin f. Celsius 2) List what each of the following units measures. (Ex. meters measure length.) a. kilogram b. Kelvin c. gram d. second 3) What do the following unit abbreviations measure? a. cm b. km c. mg d. ms 4) Convert 5.25 kilometers to meters. 5) How many microseconds (µs) are in 3 seconds? 2

3 6) Convert 7.34 X 10-3 kg to mg. 7) Convert 50 nanoseconds (ns) to megaseconds (Ms). 8) What is 2,464,000 microseconds in scientific notation? 9) Convert x to standard notation. 3

4 10) What is in scientific notation? 11) Convert 3.4 inches to kilometers. 12) Challenge: Which contains more grams: 1,000 kg or 1,000,000 mg? 4

5 13) Challenge: Can 5 micrograms be converted to meters? Explain your answer/show your work. 14) Convert 15 mg/ml to kg/l. 15) Convert 100 km/hr to m/s. 5

6 16) Challenge: Convert 5 g/cm 3 to g/m 3. 6

7 Answer Key 1) Give the abbreviation for the following units. a. kilogram: kg b. meter: m c. gram: g d. second: s e. Kelvin: K f. Celsius: C 2) List what each of the following units measures. a. kilogram: mass b. Kelvin: temperature c. gram: mass d. second: time 3) What do the following units measure? a. cm: length b. km: length c. mg: mass d. ms: time 4) Convert 5.25 kilometers to meters. 1 km contains 1,000 meters km 1,000 m = 5,250 m 1 km When converting from one unit to another, remember to cancel out units. Identical units that appear in both the top and bottom of the calculation should cancel out. At the end, you are left with only the unit you want, the meter (m). 7

8 5) How many microseconds (µs) are in 3 seconds? There are 10 6 microseconds in a second. Alternatively, you can say that there are 10-6 seconds in a microsecond. 3 s 10 6 µs = 3 x 10 6 µs 1 s You can also express the answer as 3,000,000 µs, but try to get in the habit of expressing large numbers in scientific notation. 6) Convert 7.34 X 10-3 kg to mg x 10-3 kg 1,000 g 1,000 mg = 7.34 x 10 3 mg (or 7,340) 1 kg 1 g 7) Convert 50 nanoseconds (ns) to megaseconds (Ms). In order to solve this problem, you will need to convert through the base unit, the second (s). There are 10 9 nanoseconds in a second and 10 6 seconds in a megasecond. Arrange your units in such a way that they convert from one unit to the next until you are left with the Ms. 50 ns 1 s 1 Ms = 5 x Ms 10 9 ns 10 6 s You could have also solved it the following way below, knowing that there are 10-9 nanoseconds in a second and 10-6 Megaseconds in a second. 50 ns 10-9 s 10-6 Ms = 5 x Ms 1 ns 1 s 8

9 8) What is 2,464,000 microseconds in scientific notation? Move the decimal (implied to be at the far right end of the number) to the left until there is only a single digit to the left of the decimal. 9) Convert x to standard notation. In order to solve this problem, we simply need to move the decimal place 12 places to the left, since the exponent above the 10 is negative. Correct answer: ) What is in scientific notation? In this case, since the decimal place already exists, we need to move it to the right until there is only a single non-zero number to the left of it. Correct answer: x ) Convert 3.4 inches to kilometers. Although an inch isn t an SI unit, it is still a measurement of length and can be converted to any other unit of length. In order to solve this problem, we need to convert inches into SI units. There are 2.54 cm in 1 inch, 100 cm in 1 meter, and 1,000 meters in 1 kilometer. 3.4 in 2.54 cm 1 m 1 km = 8.6 x 10-5 km 1 in 100 cm 1,000 m 9

10 12) Which contains more grams: 1,000 kg or 1,000,000 mg? The easiest way to compare these two values is to convert them to the same unit. Since they both are measurements of mass, we can convert them both to grams (g). There are 1,000 grams in a kg and 10-3 grams in a mg. 1,000 kg 1,000 g = 1,000,000 g (or 1.0 x 10 6 ) 1 kg 1,000,000 mg 1 g = 1,000 g (or 1.0 x 10 3 ) 1,000 mg Correct answer: 1,000 kg. 13) Can 5 micrograms be converted to meters? Explain your answer/show your work. A microgram (µg) is a unit of mass, and a meter (m) is a unit of length. The two cannot be converted between each other, since they measure different things. 14) Convert 15 mg/ml to kg/l. This problem involves converting two different units. We can choose to convert either of them first. Let s convert mg first. 15 mg 1 g 1 kg 1,000 ml = 1.5 x 10-2 kg/l (or 0.015) ml 1000 mg 1,000 g 1 L 10

11 15) Convert 100 km/hr to m/s. 100 km 1,000 m 1 hr = 27.8 m/s hr 1 km 3,600 s 16) Convert 5 g/cm 3 to kg/m 3. This one is a bit tricky. Any time we deal with cubed ( 3 ) or squared ( 2 ) unit conversions, we need to cube the entire conversion term that involves the cube. Note: we don t cube the g kg conversion term below because neither of those units is cubed. 5 g (100 cm) 3 1 kg = 5.0 x 10 3 kg/m 3 cm 3 (1 m) 3 1,000 g 11