1. AKA how to do the math and science needed for Chemistry
Scientific Processes
AKA how to do the math and science needed for Chemistry

2. Scientific Notation
In scientific notation a number is written as the product of two numbers: a coefficient or “M” value and 10 raised to a power.
M x 10n
The coefficient must always be a number greater than or equal to one and less than 10.
The power of ten must always be an integer.
When writing numbers greater than 1 in scientific notation, the exponent is positive and equals the number of places that the decimal has moved to the left.
6,300,000 = 6.3 x 106
When writing numbers less than 1 in scientific notation, the exponent is negative and equals the number of places the decimal has moved to the right.
= 8 x 10-6

3. Scientific Notation Practice Questions
Put the following numbers into scientific notation:
345,000 92
0.83
Put the following numbers into standard notation:
5.79 x 103
3.1 x 10-2
7.02 x 106
1.53 x 10-4
Answers:
3.45 x 105
2.96 x 10-3
9.2 x 101
8.3 x 10-1
5,790
0.031
7,020,000

4. Using Scientific Notation
When multiplying numbers in scientific notation, do so in two parts.
Multiply the “M” values first and get a value
Add the exponents on the 10.
Adjust the number at the end to put it in proper scientific notation if needed.
6.0 x 108 x 4.0 x 104 =24 x 1012 = 2.4 x 1013
When dividing numbers in scientific notation, do so in two parts.
Divide the “M” values first and get a value
Subtract the exponents on the 10
4.0 x 1014 = 0.5 x 108 = 5 x x 106

6. Scientific Notation Practice Questions
Try the following without a calculator:
4 x x 6 x =
2.5 x / 5 x =
3 x x 4 x =
Try the following with a calculator
4.13 x x x 102 =
1.6 x / x =
4.367 x x x =
24 x 108 = 2.4 x x x 10-2 = 1.2 x x x x 1015.

7. Metric system or SI – based on 10
SI base units of measure
Type of measurement
Base unit
What it measures
Length
Meters
Length of object from one end to the other
Mass
Grams
The quantity of matter an object contains
Weight
Newtons
A force, the pull on a given mass by earth’s gravity
Volume
Cubic meters or liters
Space occupied by matter
Temperature
Kelvin or Celcius
The degree of hotness of an object. This measures the motion of the molecules
Energy
Joules
The energy trapped inside molecular bonds or heat
Time
seconds
The measurement of duration. 9 billion oscillations of the cesium atom
Density
Grams/Liter
Ratio of the mass of an object and its volume

8. Metric Prefixes and Conversions
Giga
Mega
kilo
hecto
deca
base
deci
centi
milli
micro
nano G M k h da
meter liter d c m n
109
106
103
102
101
gram second
10-1
10-2
10-3
10-6
10-9
billion
million
thousand
hundred
ten
one
tenth
hundredth
thousandth
millionth
billionth
A determine the starting unit and the ending unit
Count the number of lines from start to end and notice the direction. For kilo to milli only move one space per line. The two units at each end are exceptions. They move 3 spaces per line!
Move the decimal that number of spaces in the same direction that you counted from starting unit to ending unit

9. Metric conversion practice
Convert 600 kg to g.
Convert 5000 mL to L
Convert 1 dam to mm
Convert 500 m to km
600,000 g 5 L 10,000 mm 0.5 km

10. Metric to English Conversion
Determine the unit wanted and the unit known.
Find the correct conversion factor
Arrange the conversion factor as a fraction like so: Units wanted Units known
Multiply the conversion factor with the number you want to convert. The known units will cancel out leaving you with the unit you wanted to convert to. (if they don’t cancel out, you have set up the conversion factor incorrectly)

11. English to Metric Conversions
Convert 16 in to cm
Convert 450 km to mi
Convert 45 L to gal
Convert 345 lbs to kg
Convert 75 mL to cm3
40.64 cm mi 11.9 gal 156 kg 75 cm3
1 inch = 2.54 centimeter
1 gallon = Liter
1 mL = 1 cm3
1 mile = kilometer
1 kilogram = poudns

12. Specific Gravity
Specific gravity – is a comparison of the density of a substance to the density of a reference substance, usually at the same temperature.
Water at 4 degrees Celsius has a density of 1g/mL. We will use this figure as our reference.
Specific Gravity = density of a substance (g/mL) density of water (g/mL)
The units cancel, therefore specific gravity has no units.
The specific gravity of a liquid can be measured with a hydrometer.
Uses – diabetic detection, antifreeze composition, alcohol percentage.

13. Temperature Scales Celsius
0 degrees = freezing point of water
100 degrees = boiling point of water
37 degrees = normal body temperature
Kelvin – degrees are not written on the K scale
273 K = freezing point of water
373 K = boiling point of water
0 K = matter is so cold it stops moving all together
Relationship between temperature on the Celsius scale and Kelvin scale
K = °C °C = K – 273

14. Dimensional Analysis
Calculations in Chemistry involve measuring quantities. Each of which have two parts.
The numerical portion of the measurement
The units in which the measurement was taken.
For example 27.4 cm
When multiplying the quantities the numbers are multiplied, then the units are multiplied.
Example: 1.2 cm x 2.0 cm = 2.4 cm2

15. Factor – Label Method
A conversion factor is a fraction in which the numerator and denominator both represent the same measurement.
100 cm is a conversion factor since both the m numerator and denominator represent the same length (1 meter)
The value of all conversion factors must be equal to 1

16. FLM Conversions How many seconds are there in one week?
How many minutes are there in a year?
minutes
What is the volume of a 25 g substance that has a density of 4.8 g/mL?
5.2 mL
What is the mass of 92 mL of a substance that has a density of 39.1 g/mL?
3597 g

17. Graphing
Graphing is used to show relationships between variables (Quantities)
To predict trends
Independent variable – the variable that you control or manipulate
Independent variable goes on the X – axis
Dependent variable – the variable that changes in response to the independent variable
Dependent variable goes on the y – axis
Choose a good scale:
Calculate Range and divide by number of spaces

18. Scientific measurements
Quantitative measurements – give results in a definite form, usually as numbers and units.
Example: There are 25 mL of the liquid
Qualitative measurements – give results in a descriptive, nonnumeric form.
Example: The liquid is blue

19. Accuracy vs. Precision
Accuracy – how close a measurement comes to the true value of whatever is measured.
Precision – is concerned with reproducibility of the measurement (how many times you can get the same measurement)
Significant figures – deals with the precision with which measurements are taken. The least precise measurement must be used in determining significant digits.

20. Accuracy vs. Precision

21. Rules for determining which digits are Significant.
Every nonzero digit in a recorded measurement is significant.
Zeros appearing between nonzero digits are significant. 206
Zeros appearing in front of all nonzero digits are not significant. They are acting as placeholders
Zeros at the end of a number and to the right of a decimal point are significant
Zeros at the end of a number with no decimal point are not significant. 38,000
Every number in front of the x 10 of scientific notation is significant.

22. How many sig figs?
35045
0.0025
0.0480
98300
3.800 x 1015

23. Calculating Using Sig Figs
When multiplying and dividing, limit and round your answer to the least number of significant figures in any of the numbers which you are multiplying or dividing.
Example: cm x .75 cm cm2  cm2
When adding and subtracting, limit and round your answer to the least number of decimal places in any of the numbers that are being added or subtracted.
Example: g g g  g

24. Calculating Using Sig Figs
23.7 x 3.9 =
45.76 x 0.25 =
6.47 x 64.5 =
1.678 / 0.42 =
/ 3.74 =

25. Calculating Using Sig Figs

26. Making measurements in the lab
There are two kinds of numbers in the world: exact and inexact
If I quickly measure the width of a piece of notebook paper, I might get mm (2 sig figs). If I am more precise, I might get 216 mm (3 sig figs). An even more precise measurement would be mm (4 sig figs).
When doing measurements, add one estimated digit.
Example: If the ruler has a marking for every 0.1 mm and you can see the string you are measuring is about halfway between 4.5 mm and 4.6 mm long, then you would estimate the length is 4.55 mm long.
In a graduated cylinder, the surface of the liquid is curved. This is called a meniscus. When you read the volume on a graduated cylinder, read it from the very bottom of the meniscus and make sure it’s at eye level.

27. Making Measurements