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Review Module 1 Material
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Module 1 Review
Accuracy:
How close a measured value is to the accepted or real value.
Precision:
The degree of reproducibility of a measured quantity; how close a series of measurements of the same quantity are to one other.
Volume
Volume is a measure of space. It is a unit of length raised to the third power.
The SI unit of length is the meter. One meter cubed is equivalent to 1000 L. Litres, which are a convenient unit for scientific measurements, are a more common measurement unit than meters cubed.
1 L = 1 dm\(^{3}\)
1 L = 1000 mL
1 cm\(^{3}\) = 1 ml
Density
A ratio of mass (m) to volume (V) of a substance.
\(\text{Density} = \frac{\text{Mass}}{\text{Volume}}\)
SI Base Units
Click on the symbol button to reveal the definition.
Note:
Note: Precise definitions of the SI units are not necessary to memorize. Rather, the relationships between the units and how to use them are the important parts to know.
| Quantity | Unit | Symbol |
|---|---|---|
| Length | Meter | m |
| Temperature | Kelvin | K |
| Time | Second | s |
| Mass | Kilogram | kg |
| Amount of Substance | Mole | mol |
| Electric Current | Ampere | A |
| Luminous Intensity | Candela | cd |
SI Prefixes: Units of Measure for All Sizes
Multipliers that change unit values by multiples of ten.
Significant Figures
An accepted method for preserving the precision of a measurement when recording data or doing calculations.
1.
Non-zero digits are significant.
2.
Exact numbers are significant.
3.
Contained zeros are significant.
4.
Leading zeros are not significant.
5.
Trailing zeros have significance as follows:
a.
After a decimal point, significant
b.
After a non-zero number and before a decimal point, significant
c.
After a non-zero number that in not a decimal number, generally a place holder
For an even more detailed breakdown on significant figures click the button below to view.
Scientific Notation
A notation for expressing large and small numbers as a small decimal between one and ten multiplied by a power of ten.
How to write using scientific notation:
1.
Move the decimal point to the left or right to reach a decimal number between one and ten.
2.
Write the number obtained in step 1 multiplied by 10 raised to the number of places the decimal point was moved.
2a.
If the decimal is moved to the left, the power is positive.
Example: \(140000 = 1.4\)x\(10^{5}\)
2a.
If the decimal is moved to the right, the power is negative.
Example: \(0.000014 = 1.4\)x\(10^{-5}\)
Unit Analysis and Problem Solving
Book-keeping method for units in a calculation
Indicates errors in a multi-step calculation
Provides the units for the final answer
Over all method of “unit analysis”:
write the units with every number you include in a series of calculations
String your calculations together as a series of multiplications or divisions before doing any math
Cancel your units to see the calculation evolve
Gives you a hint about what to do next
Calculations: Converting from One Unit to Another
Unit analysis:
A method that uses a conversion factor to convert a quantity expressed in one unit to an equivalent quantity in a different unit.
Conversion factor:
States the relationship between two different units.
original quantity x conversion factor = equivalent quantity
For example converting between length units
Given that 1 meter = 39.37 inches
Conversion factors\(\frac{1\,m}{39.37 \,\text{inches}} \text{or} \frac{39.37\, \text{inches}}{1\,m}\)
The same relationship, just invert as necessary to give you the units you need
Problem Solving Examples
How many moles of Oxygen atoms are there in a 10 mL volume of water?
What is being asked?
Given a volume can you calculate a number of atoms?
What data is provided?
Data: 10 mL of water
What do I need to know?
Need to know: water is H\(_2\)O, density of water, molecular weight of water
How do I need to state the answer?
Answer in mols of O
Convert volume of water to moles of Oxygen
Calculation is Volume \(\to\) mass of H\( _2\)O \(\to\) mols of H\(_2\)O \(\to\) mols of O
