Accelerated Physical Science Study Guide:
Volume, Mass, Measurement, Significant Digits, Conversions
Covers IPS book sections 2.1-2.5, 2.10-2.12, 2.14-2.15
Lab review – know procedures, measurements, calculations, principles
2.3 – Measuring Volume by Displacement of Water
2.10 – Mass of Dissolved Salt
2.11 – Mass of Ice and Water
2.12 – Mass of Mixed Solutions
2.14 – Mass of a Gas
Units and Measurement
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Know these SI units
o mass (gram, g)
o length (meter, m and centimeter, cm)
o volume (cubic meter, m3; cubic centimeter, cm3; and liter, L)
Know metric prefixes (mega, kilo, deci, centi, milli, micro, nano) and be able to convert
between units using them. e. g. 1 L = 1000 mL, 1 gigameter = 109 meters
Know scientific notation, how to convert a number into scientific notation and how to go
from scientific notation back to a regular number. Know how to multiply and divide in
scientific notation
Uncertainty – comes from equipment and from estimation
o Any measurement value contains certain digits and one uncertain digit
o The uncertain digit is estimated
Precision – a reliable measurement – one that gives about the same result again and again
Accuracy – a measurement that is close to the accepted or true value
Significant Digits
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Significant digits – certain AND estimated digits
o Non-zero digits – ALWAYS significant
o Leading zeros – NEVER significant
o Trapped zeros – ALWAYS significant
o Trailing zeros – ONLY significant when the number contains a decimal point
o When using scientific notation, ALL significant digits are used
Calculating with significant digits
o Exact numbers (counting numbers, numbers in conversions) do NOT affect the
number of significant digits in answer
o Multiplication and division – answer has the same number of significant digits as
the measurement with the fewest number of significant digits
o Addition and subtraction – answer has the same uncertainty as the number with
the largest uncertainty
Conversions, Dimensional Analysis (converting from one unit to another)
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Start with unit equalities
e. g. 1 L = 1000 mL, 1 mL = 1 cm3
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Make conversion factors from the unit equalities. A conversion factor always = 1. Using
the unit equalities above, the conversion factors are:
1L
1000 mL
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1000 mL
1L
1 mL
1 cm3
1 cm3
1 mL
Multiply the number you wish to convert by the conversion factor that results in
canceling the first unit and leaving the correct unit for the answer. The correct conversion
factor will have the unit to be canceled in the denominator and the unit for the answer in
the numerator.
Converting 350 mL to L:
350 mL x
1L
=
1000 mL
0.35 L
Converting 350 mL to cm3:
350 mL x
1 cm3
1 mL
=
350 cm3