1.2: Units

UNITS OF MEASUREMENT

Process of obtaining a value (how much) and unit (of what).

LENGTH	MASS	TIME	TEMPERATURE	VOLUME
Meter: m	Gram: g	Seconds: s	Kelvin: K	Liter: L

Prefix Metric System - Size of Unit for Length, mass, time and volume

Giga	Mega	Kilo	BaseUnit	Deci	Centi	Milli	Micro	Nano
G	M	K	m, l, s, g	d	c	m	μ	n
10⁹	10⁶	10³	10	10ˉ¹	10ˉ²	10ˉ³	10ˉ⁶	10ˉ⁹

Converting Between Units in Metric System:

Exercise:

6394 μm = 0.000006394 Km

0.000421 Gg = 421000000 10ˉ³

TEMPERATURE - Measuring the average of Kinetic Energy (Motion)

Fahrenheit	Kelvin	Celsius
°F = (1.8)°C + 32	K = °C + 273	°C

Exercise:

Convert 77 Kelvin into Fahrenheit.

(77 K = ???????? °F)

Then,

Step 1 = Convert Kelvin into Celsius:

1. K = °C + 273

2. °C = 77 - 273

3. °C = -196

Step 2 = Convert Celsius into Fahrenheit:

4. °F = 1.8 °C +32

5. °F = (1.8) x (-196) + 32

6. °F = -321

DERIVED UNITS - A combination of base units

* Velocity =  meter per second

* Volume = (length) x (width) x (height) = cm x cm x cm = cm³ = 1 mL

* Density =  The relative mass per unit volume

Exercise:
Find the density given:

Mass = 374.5 g and Volume = 41.8 mL

Step 1 =  Density = 

1. -->Density = 

2. -->Density = 8.96 g/mL

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HOMEWORK EXERCISES

1. Three spheres of equal size are composed of aluminum (density = 2.70g/ml), silver (density = 10.49g/ml), and nickel (density = 8.92g/ml). List the spheres from lightest to heaviest.

① Aluminum (density = 2.70g/ml) < nickel (density = 8.92g/ml) < silver (density = 10.49g/ml)

2. Make the following conversions:

a) 62 °F to °C

①   = 17 °C

b) 216.7 °C to °F

① (1.8 x 216.7) + 32 = 422.1 °F

c) 233 °C to K

① 233 + 273 = 506 K

d) 315 K to °F

① 315 - 173

② (42 x 1.8) + 32 = 108 °F

e) 2500 °F to K

① 

② 1371 + 273 = 1644 K