Chapter 3

CHM 130

GCC Chemistry

3.1 Metric System:Quantity Basic Unit Symbol

length meter m mass gram g

volume liter L time second s

Metric prefixes make the basic unit larger or smaller.

Know the following metric prefixes!

3.2 METRIC CONVERSION FACTORS

1 m = ______ cm 1 m = _______ m

1 m = ______ dm 1 m = _______mm1 km = ______m

Hints = centi like 100 cents in $, deci like 10 dimes in a $, milli like millipede, micro like microscopic (very small)

You must memorize these. Note instead of meters, they could be liters or grams.

100

10

1000

1,000,000

1000

Fractions (Unit Factors)

• All of the preceding equalities (or unit equations) can be put in fraction form. Write fractions for them.

kg 1

g 1000

m 1

mm 1000

cg 100

g 1

g 1

dg 10

g 1

g1,000,000u

mL 1000

L 1

m 1

cm 100

m 1000

km 1

Some examples:

3.3 Metric Conversions

How many liters are in 2389 mL?

How many kilometers are in 12,300 cm?

2389 mL = 2.389 L

mL 1000

L 1

12,300 cm = 0.123 km

m 1000

km 1

cm 100

m 1

3.4 METRIC-ENGLISH CONVERSIONS

These conversions will be given: 1 inch = 2.54 cm

1 lb = 454 g

1 qt = 946 mL

We expect you to know 1 foot = 12 inches, 3 feet = 1 yard, 60 s = 1 min, 60 min = 1 hour, 24 hour = 1 day, etc...

Practice Probs – Work on board and show each step

1. How many pounds are in 248 grams?2. How many inches are in 3.54 x 10-3 km?3. How many kg are in 43,500 mg?4. A 2.0 liter soda bottle contains how many quarts?5. A dose of 5375 L of morphine is how many liters?

1. 248 g (1 lb / 454 g) = 0.546 lbs

2. 3.54 x 10-3 km (1000 m / 1 km)(100 cm / 1 m)(1 inch / 2.54 cm) = 139 inches

3. 43,500 mg (1 g / 1000 mg)(1 kg / 1000 g) = 0.0435 kg

4. 2.0 L (1000 mL / 1 L)( 1 quart / 946 mL) = 2.1 quarts

5. 5375 L (1 L / 1,000,000 L) = 5.375 x 10-3 L Watch sig fig

3.5 Three Ways to Determine Volume

1. Measured directly using graduated cylinder, pipets, burets, etc.

2. Rectangle, cylinder, sphere can be determined by calculation.

3. Other solids are found indirectly by liquid displacement.

Remember 1 mL = 1 cm3 = 1 cc

VOLUME BY CALCULATION

volume = length width height

Calculate the volume of a shoe box measuring 24 cm by 11 cm by 16 cm.

V = (24 cm) (11 cm) (16 cm) = 4200 cm3

(2 sig fig)

3.6 VOLUME BY DISPLACEMENT

A diamond is placed in a graduated cylinder containing 20.0 mL of water. The volume rises to 34.7 mL. What is the volume of the rock? Who knows what element is in diamonds??? So what state of matter is this element?

V = 34.7 mL – 20.0 mL = 14.7 mL

Carbon is Solid

3.7 DENSITY

density: The amount of mass per volume.

volumemass

density

3cm

g

mL

gdensity units: =cc

g=

Think of density as how much “stuff” is in a given space.

Which state is most dense?

Least?

density air = 0.00129 g/cm3

density water = 1.00 g/cm3

density gold = 18.9 g/cm3

solid

gas

Sink or Float

Note how some objects float on water (a cork), but others sink (a penny). That's because objects that have a higher density than a liquid will sink in the liquid, but those with a lower density than the liquid will float. Since water's density is about 1.00 g/cm3, a cork's density must be (< or >) than 1.00 g/cm3, and a penny's density must be (< or >) 1.00 g/cm3.

Cork < Penny >

Matching

Ice cube (d=0.917 g/cm3)

honey (d=1.50 g/cm3)

iron cube (7.87 g/cm3)

hexane (d=0.65 g/cm3)

rubber cube (d=1.19 g/cm3)

S1L2S3L1S2

DENSITY CALCULATIONS

Use density as a conversion factor (fraction)!

Ex: Give 2 ratios for the density of chloroform. (d = 1.48 g/mL)

Ex: How many grams would 17.5 mL of chloroform mass?

Ex: How many mL would 0.0735 grams of chloroform occupy?

g1.48mL

andmL

g1.48

17.5 mL (1.48 g/mL) = 25.9 g

0.0735 g (mL / 1.48g) = 0.0497 mL

3.8 TEMPERATURE Temperature: Measure of atoms’ energy.

• Hot molecules move _______ and have _______ energy.

• Cold molecules move ______ and have _______ energy.

• Temperature is measured with a thermometer.

• Check this out! (slide the Temp control)

slow

fasthigh

low

3 scales: Fahrenheit (°F); Celsius (°C) & Kelvin (K)

Zero Kelvin is the lowest possible temperature where molecules stop moving; called absolute zero. So there is no such thing as negative Kelvins.

Temperature Conversions-these are provided on exams

32 + 1.8)C( = F 1.832) - F( = C

K = ˚C + 273

Ex: Phoenix can get up to 115oF. What is this in Celsius and Kelvin?

46 Celsius and 319 Kelvin

HEATHeat: Measures total energy of all atoms.

1. Which of these two beakers has the higher temperature? Why?

2. Which has the greater amount of heat? Why?

Same! Both at 100

Second, more water, more molecules moving, more energy, more heat

Heat Transfer

• Heat transfers from higher temperatures to lower

• Heat transfers from hot to cold!

Consider holding a hot cookie straight from the oven. What loses heat? What gains heat?

Cookie

Hand

A piece of metal is placed in the freezer. The metal is then put in a bucket of hot water.

• Does the temperature of the metal increase, decrease, or stay the same? Explain.

• Does the temperature of the water in the bucket increase, decrease, or stay the same? Explain.

Temperature of metal increases as it gains heat

Temperature of water decreases as it loses heat

Heat transfers FROM water TO metal.

Exam I Coming Soon• Study online NOTES

• Study online worksheets

• Study self-test Text problems

• Practice conversion, density, and temperature problems

• Know sig fig rules!!!

• Don’t forget to turn in your homework if any

Review probs if time

• How many meters per second is 95 miles per hour? Given: 5280 feet = 1 mile and 2.54 cm = 1 inch (don’t go from miles to km)

• Martin’s head is 19 inches around. How many mm is this?

• Dr. Kim’s famous vodka punch has a density of 1.15 g/mL. How many mL is 24.5 grams?

• If Heather drank 445 mL of punch, how many cups is this? Given 946 mL = 1 qt. Is she going to be sick???

Chapter 3 Self-Test page 73

• Try # 1, 2, 4-8, 10-13

• Answers in Appendix J

• You should really try these on your own. Work them out BEFORE looking at the answers!!!