Chapter 3 CHM 130 GCC Chemistry

3.1 Metric System: Metric prefixes make the basic unit larger or smaller.

Know the following metric prefixes!

3.2 METRIC CONVERSION FACTORS 1 m = ______ cm 1 m = _______ mm 1 m = ______ dm 1 m = _______mm 1 km = ______m 100 1,000,000 10 1000 1000 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.

Fractions (Unit Factors) All of the preceding equalities (or unit equations) can be put in fraction form. Write fractions for them. 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 12,300 cm = 0.123 km

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 How many pounds are in 248 grams? How many inches are in 3.54 x 10-3 km? How many kg are in 43,500 mg? A 2.0 liter soda bottle contains how many quarts? A dose of 5375 mL of morphine is how many liters? 248 g (1 lb / 454 g) = 0.546 lbs 3.54 x 10-3 km (1000 m / 1 km)(100 cm / 1 m)(1 inch / 2.54 cm) = 139 inches 43,500 mg (1 g / 1000 mg)(1 kg / 1000 g) = 0.0435 kg 2.0 L (1000 mL / 1 L)( 1 quart / 946 mL) = 2.1 quarts 5375 mL (1 L / 1,000,000 mL) = 5.375 x 10-3 L Watch sig fig

3.5 Three Ways to Determine Volume Measured directly using graduated cylinder, pipets, burets, etc. Rectangle, cylinder, sphere can be determined by calculation. 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? Carbon is Solid V = 34.7 mL – 20.0 mL = 14.7 mL

3.7 DENSITY density: The amount of mass per volume. density units: = = Think of density as how much “stuff” is in a given space.

Which state is most dense? Least? solid Which state is most dense? Least? gas density air = 0.00129 g/cm3 density water = 1.00 g/cm3 density gold = 18.9 g/cm3

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 S1 L2 S3 L1 S2 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) S1 L2 S3 L1 S2

Use density as a conversion factor (fraction)! 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? 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) fast high slow 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 K = ˚C + 273 Ex: Phoenix can get up to 115oF. What is this in Celsius and Kelvin? 46 Celsius and 319 Kelvin

HEAT Heat: 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 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!!!