<< Chapter < Page Chapter >> Page >

Key concepts and summary

Measurements are made using a variety of units. It is often useful or necessary to convert a measured quantity from one unit into another. These conversions are accomplished using unit conversion factors, which are derived by simple applications of a mathematical approach called the factor-label method or dimensional analysis. This strategy is also employed to calculate sought quantities using measured quantities and appropriate mathematical relations.

Key equations

  • T °C = 5 9 × T °F 32
  • T °F = 9 5 × T °C + 32
  • T K = °C + 273.15
  • T °C = K 273.15

Chemistry end of chapter exercises

Write conversion factors (as ratios) for the number of:

(a) yards in 1 meter

(b) liters in 1 liquid quart

(c) pounds in 1 kilogram

(a) 1.0936 yd 1 m ; (b) 0.94635 L 1 qt ; (c) 2.2046 lb 1 kg

Got questions? Get instant answers now!

Write conversion factors (as ratios) for the number of:

(a) kilometers in 1 mile

(b) liters in 1 cubic foot

(c) grams in 1 ounce

Got questions? Get instant answers now!

The label on a soft drink bottle gives the volume in two units: 2.0 L and 67.6 fl oz. Use this information to derive a conversion factor between the English and metric units. How many significant figures can you justify in your conversion factor?

2.0 L 67.6 fl oz = 0.030 L 1 fl oz
Only two significant figures are justified.

Got questions? Get instant answers now!

The label on a box of cereal gives the mass of cereal in two units: 978 grams and 34.5 oz. Use this information to find a conversion factor between the English and metric units. How many significant figures can you justify in your conversion factor?

Got questions? Get instant answers now!

Soccer is played with a round ball having a circumference between 27 and 28 in. and a weight between 14 and 16 oz. What are these specifications in units of centimeters and grams?

68–71 cm; 400–450 g

Got questions? Get instant answers now!

A woman's basketball has a circumference between 28.5 and 29.0 inches and a maximum weight of 20 ounces (two significant figures). What are these specifications in units of centimeters and grams?

Got questions? Get instant answers now!

How many milliliters of a soft drink are contained in a 12.0-oz can?

355 mL

Got questions? Get instant answers now!

A barrel of oil is exactly 42 gal. How many liters of oil are in a barrel?

Got questions? Get instant answers now!

The diameter of a red blood cell is about 3 × 10 −4 in. What is its diameter in centimeters?

8 × 10 −4 cm

Got questions? Get instant answers now!

The distance between the centers of the two oxygen atoms in an oxygen molecule is 1.21 × 10 −8 cm. What is this distance in inches?

Got questions? Get instant answers now!

Is a 197-lb weight lifter light enough to compete in a class limited to those weighing 90 kg or less?

yes; weight = 89.4 kg

Got questions? Get instant answers now!

A very good 197-lb weight lifter lifted 192 kg in a move called the clean and jerk. What was the mass of the weight lifted in pounds?

Got questions? Get instant answers now!

Many medical laboratory tests are run using 5.0 μL blood serum. What is this volume in milliliters?

5.0 × 10 −3 mL

Got questions? Get instant answers now!

If an aspirin tablet contains 325 mg aspirin, how many grams of aspirin does it contain?

Got questions? Get instant answers now!

Use scientific (exponential) notation to express the following quantities in terms of the SI base units in [link] :

(a) 0.13 g

(b) 232 Gg

(c) 5.23 pm

(d) 86.3 mg

(e) 37.6 cm

(f) 54 μm

(g) 1 Ts

(h) 27 ps

(i) 0.15 mK

(a) 1.3 × 10 −4 kg; (b) 2.32 × 10 8 kg; (c) 5.23 × 10 −12 m; (d) 8.63 × 10 −5 kg; (e) 3.76 × 10 −1 m; (f) 5.4 × 10 −5 m; (g) 1 × 10 12 s; (h) 2.7 × 10 −11 s; (i) 1.5 × 10 −4 K

Got questions? Get instant answers now!
Practice Key Terms 3

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Chemistry' conversation and receive update notifications?

Ask