Follow along in your text

Chapter 1 Section 2

Pages 10 - 16

Units of Measure & Conversions

Number vs. Quantity

Quantity - number + unit

UNITS MATTER!!

Derived Units Combination of base units.

Volume (m3 or cm3) length length length

D = MV

1 cm3 = 1 mL1 dm3 = 1 L

Density (kg/m3 or g/cm3)mass per volume

DensityM

ass

(g)

Volume (cm3)

ΔxΔyslope D

VM

Problem-Solving Steps

1. Analyze

2. Plan

3. Compute

4. Evaluate

Density An object has a volume of 825 cm3 and a

density of 13.6 g/cm3. Find its mass.

GIVEN:V = 825 cm3

D = 13.6 g/cm3

M = ?

WORK:M = DV

M = (13.6 g/cm3)(825cm3)

M = 11,200 g

VMD

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/mLV = ?M = 25 g

WORK:V = M DV = 25 g 0.87 g/mL

V = 29 mLVMD

Warm-Up:Put the following calculations into the correct significant figures. The “calculator answer” is

already provided for you.

1) 36.75 g + 450 g + 9.750 g = 496.5 g2) 29.0 m x 0.004030 m = 0.11687 m2

3) 600.000 L – 14.7561 L = 585.2439 L4) 219 mm3 / 17 mm2 = 12.88235294 mm5) 75.0 mol + 91.00 mol + 22.000 mol = 188 mol6) 100 kg – 81 kg = 19 kg7) 0.0057 g/mL / 91.2 g = 0.0000625 mL8) (27.0 m x 0.312 m) + (105 m x 0.190 m) = 28.374 m2

Follow along in your text

Chapter 1 Section 2

Pages 10 - 19

Unit Conversionsof Measurements

SI UnitsQuantity Base Unit Abbrev.LengthMass

TimeTemp

meterkilogram

secondKelvin

mkg

sK

Amount mole mol

SymbollmtT

nVolume liter LVPressure Pascal PaP

SI Units

mega- M 106

deci- d 10-1

centi- c 10-2

milli- m 10-3

Prefix Symbol Factor

micro- 10-6

nano- n 10-9

pico- p 10-12

kilo- k 103

BASE UNIT --- 100

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 leftor right?

SI Prefix Conversions

mega- M 106

deci- d 10-1

centi- c 10-2

milli- m 10-3

Prefix Symbol Factor

micro- 10-6

nano- n 10-9

pico- p 10-12

kilo- k 103

mov

e le

ftm

ove

right

BASE UNIT --- 100

33

cmgcm

Dimensional Analysis The “Factor-Label” Method

Units, or “labels” are canceled, or “factored” out

g

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

NUMBERUNIT

NUMBER

UNIT

532 m = _______ km0.532

Dimensional Analysis Lining up conversion factors:

1 in = 2.54 cm2.54 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 L1.057 qt

= 946 mL

qt mL

1000 mL1 L

Dimensional Analysis You have 1.5 pounds of gold. Find its volume

in cm3 if the density of gold is 19.3 g/cm3.

lb cm3

1.5 lb 1 kg2.2 lb

= 35 cm31000 g

1 kg1 cm3

19.3 g

Dimensional Analysis How many liters of water would fill a

container that measures 75.0 in3?

75.0 in3 (2.54 cm)3

(1 in)3= 1.23 L

in3 L

1 L1000 cm3

Dimensional AnalysisYour European hairdresser wants to cut your hair

8.0 cm shorter. How many inches will he be cutting off?

8.0 cm 1 in2.54 cm

= 3.2 in

cm in

Dimensional Analysis

Lake Taylor’s football team needs 550 cm for a 1st down. How many yards is this?

550 cm 1 in2.54 cm

= 6.0 yd

cm yd

1 ft12 in

1 yd3 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 cm1 m

= 86 pieces

cm pieces

1 piece1.5 cm

SI Prefix Conversions Practice

1) 20 cm = ______________ m

2) 0.032 L = ______________ mL

3) 45 m = ______________ nm

4) 805 dm = ______________ km

0.2

0.0805

45,000

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