Follow along in your text Chapter 1 Section 2 Pages Units of Measure & Conversions

Number vs. Quantity  Quantity - number + unit UNITS MATTER!!

Derived Units  Combination of base units.  Volume (m 3 or cm 3 )  length  length  length D = MVMV 1 cm 3 = 1 mL 1 dm 3 = 1 L  Density (kg/m 3 or g/cm 3 )  mass per volume

Density Mass (g) Volume (cm 3 )

Problem-Solving Steps 1. Analyze 2. Plan 3. Compute 4. Evaluate

Density  An object has a volume of 825 cm 3 and a density of 13.6 g/cm 3. Find its mass. GIVEN: V = 825 cm 3 D = 13.6 g/cm 3 M = ? WORK : M = DV M = (13.6 g/cm 3 )(825cm 3 ) M = 11,200 g

Density  A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid? GIVEN: D = 0.87 g/mL V = ? M = 25 g WORK : V = M D V = 25 g 0.87 g/mL V = 29 mL

Warm-Up: Put the following calculations into the correct significant figures. The “calculator answer” is already provided for you. 1)36.75 g g g = g 2)29.0 m x m = m 2 3) L – L = L 4)219 mm 3 / 17 mm 2 = mm 5)75.0 mol mol mol = 188 mol 6)100 kg – 81 kg = 19 kg 7) g/mL / 91.2 g = mL 8)(27.0 m x m) + (105 m x m) = m 2

Follow along in your text Chapter 1 Section 2 Pages Unit Conversions of Measurements

SI Units QuantityBase UnitAbbrev. Length Mass Time Temp meter kilogram second Kelvin m kg s K Amountmolemol Symbol l m t T n VolumeliterL V PressurePascalPa P

SI Units mega-M10 6 deci-d10 -1 centi-c10 -2 milli-m10 -3 PrefixSymbolFactor micro-  nano-n10 -9 pico-p kilo-k10 3 BASE UNIT

SI Prefix Conversions 1.Find the difference between the exponents of the two prefixes. 2.The “BABY WAY”: Move the decimal that many places. To the left or right?

SI Prefix Conversions mega-M10 6 deci-d10 -1 centi-c10 -2 milli-m10 -3 PrefixSymbolFactor micro-  nano-n10 -9 pico-p kilo-k10 3 move left move right BASE UNIT

Dimensional Analysis  The “Factor-Label” Method  Units, or “labels” are canceled, or “factored” out

Dimensional Analysis  Steps: 1. Identify starting & ending units. 2. Line up conversion factors so units cancel. 3. Multiply all top numbers & divide by each bottom number. 4. Check units & answer.

= SI Prefix Conversions NUMBER UNIT NUMBER UNIT 532 m = _______ km 0.532

Dimensional Analysis  Lining up conversion factors: 1 in = 2.54 cm 2.54 cm 1 in = 2.54 cm 1 in 1 in = 1 1 =

Dimensional Analysis  How many milliliters are in 1.00 quart of milk? 1.00 qt 1 L qt = 946 mL qtmL 1000 mL 1 L 

Dimensional Analysis  You have 1.5 pounds of gold. Find its volume in cm 3 if the density of gold is 19.3 g/cm 3. lbcm lb 1 kg 2.2 lb = 35 cm g 1 kg 1 cm g

Dimensional Analysis  How many liters of water would fill a container that measures 75.0 in 3 ? 75.0 in 3 (2.54 cm) 3 (1 in) 3 = 1.23 L in 3 L 1 L 1000 cm 3

Dimensional Analysis Your European hairdresser wants to cut your hair 8.0 cm shorter. How many inches will he be cutting off? 8.0 cm1 in 2.54 cm = 3.2 in cmin

Dimensional Analysis Lake Taylor’s football team needs 550 cm for a 1 st down. How many yards is this? 550 cm 1 in 2.54 cm = 6.0 yd cmyd 1 ft 12 in 1 yd 3 ft

Dimensional Analysis A piece of wire is 1.3 m long. How many 1.5-cm pieces can be cut from this wire? 1.3 m 100 cm 1 m = 86 pieces cmpieces 1 piece 1.5 cm

SI Prefix Conversions Practice 1) 20 cm = ______________ m 2) L = ______________ mL 3) 45  m = ______________ nm 4) 805 dm = ______________ km ,000 32