Cheat Sheet for Quiz 1 (Lab 1 & Lab 2)

Lab 1: “Measurement and Significant Figures”

The metric system is a decimal systems in which

measurement of each type are related by factors of

10.

The metric system has one standard unit for each

type of measurement.

Table 1.1 “Metric Units”

Measurement Metric Unit Symbol

Length Meter M

Mass Gram G

Volume Liter L

Temperature Degrees Celsius;

Kelvins

°C; K

Time Second s

A unit must always be included when reporting a

measurement.

For larger and smaller measurements, prefixes are

attached in front of the standard unit.

Table 1.2 “Some Prefixes in the Metric System”

Prefix Symbol Meaning

Kilo K 1000

Deci D 0.1 (1/10

Centi C 0.01 (1/100)

Milli M 0.001 (1/1000)

Measured numbers – when we measure the length,

volume, or mass of an object. Example would be

weight which is a measured number.

Exact numbers – obtained when we count objects.

In measured numbers, all the reported figures are

called significant figures.

o The first sign. Figures is the first nonzero digit

o The last sign. Figures is always the estimated

digit

o Zeros b/t other digits or at the end of a decimal

number are counted as sign. Figures.

o Leading zeros are not significant; they are

placeholders.

o Zeros are not sign. In large numbers with no

decimal points; they are placeholders needed to

express the magnitude of the number.

Table 1.3 “Examples of Counting Significant Figures”

Measurement Number of

Significant

Figures

Reason

455.2 cm 4 All nonzero digits

are significant

0.80 m 2 A following zero

in a decimal

number is

significant

50.2 L 3 A zero b/t

nonzero digits is

significant

0.0005 lb 1 Leading zeros

are not significant

25,000 ft 2 Placeholder

zeros are not

significant

Table 1.4 “Some Metric Units Used to Measure Length”

Length Symbol Meaning

1 kilometer Km 1000 meters (m)

1 decimeter Dm 0.1 m (1/10 m)

1 centimeter Cm 0.01 m (1/100 m)

1 millimeter Mm 0.001 m (1/1000

m)

The standard unit of length in the metric system is the

meter (m).

The volume of a substance measures the space it

occupies.

Table 1.5 “Some Metric Units Used to Measure Volume”

Unit of Volume Symbol Meaning

1 kiloliter kL 1000 liters (L)

1 deciliter dL 0.1 L (1/10 L)

1 milliliter mL 0.001 L (1/1000

L)

Why does a meniscus exist?

o A meniscus is the curved surface at the top of a

column of liquid.

o It has to do with the nature of the water

molecules and glass molecules themselves.

Water is made up of polar molecules, which have

positively and negatively charged ends. Since

opposites attract, the positive sides attract the

negative sides, and all of the molecules stick to

one another.

o Must read at its lowest point (center) to obtain the

correct volume measurement for the liquid.

The mass of an object indicates the amount of matter

present in that object.

Mass:

o Kilogram (kg) 1000 g

o Gram (g) 1000 mg

o Milligram (mg) 1/1000 g (0.0001 g)

Information:

o 1 m = 100 cm

o 1 m = 1000 mm

o 1 cm = 10 mm

Lab 2: “Conversion Factors in Calculations”

Rounding off:

o If the first number to be dropped is less than

5, it and all following numbers are dropped.

o If the first number to be dropped is 5 or

greater, the numbers are dropped and the

value of the last retained digit is increased by

1.

o When you round a large number, the correct

magnitude is retained by replacing the

dropped digits with placeholder zeros.

Addition/Subtraction:

o When you add or subtract numbers, the

reported answer has the same number of

decimal places as the measured number

with the fewest decimal places.

Measurement:

o 1 in. = 2.54 cm

o 1 L = 1000 mL

o 1 qt = 946 mL

o 1 kg = 1000 g

o 1 lb = 454 g

o 1 lb = 16 oz

o 1 qt = 2 pt

o 1 kg = 2.20 lb

o 1 m = 39.4 in.

o 1 L = 1.06 qt

Percent by Mass:

o Mass (g) of component 1 / Mass (g) of the

mixture * 100 = % of component 1

Converting Temperature:

o TF = 1.8 (TC) = 32

o TC = (TF – 32) / 1.8

o TK = TC + 273

Information on Temperature:

o Temperature – measures the intensity of

heat in a substance

o Celsius scale, water freezes at 0°C

o Fahrenheit scale, water freezes at 32°F

Formulas for Volume:

o Cube = Length

V = L3

o Rectangular Solid = Length, Width, Height

V = L * W * H

o Cylinder = Diameter, Height

V = 3.14D2H / 4

Taring a container on an electronic balance:

o The mass of a container on an electronic

balance can be set to 0 by pressing the tare

bar. As a substance is added to the

container, the mass shown on the readout is

for the substance only.

Length:

o 1 ft = 12 in.

o 1 yard = 3 ft.

o 1 mile = 5280 ft.

o 1 km = 1000 m

o 1 m = 1000 mm

o 1 cm = 10 mm

o 2.54 cm = 1 in.

o 1 m = 39.4 in.

o 1 km = 0.624 mi

Volume:

o 1 qt = 4 cups

o 1 qt = 2 pt

o 1 gallon = 4 qt

o 1 L = 1000 mL

o 1 dL = 100 mL

o 1 mL = 1 cm3

o 946 mL = 1 qt

o 1 L = 1.06 qt

Mass:

o 1 lb = 16 oz

o 1 kg = 1000 g

o 1 g = 1000 mg

o 1 kg = 2.20 lb

o 454 g = 1 lb

Time:

o 1 h = 60 min

o 1 min = 60 s