Unit+1

**Qualitative (quality):** deals with descriptions and data that can be observed, not measured (ex. color, texture, smell, taste, appearance, etc.)
Practice:

Sig Figs:
1. Nonzero digits are always significant • Ex. 1,275.3 = (5) 2. Zeros between non-zero numbers are significant • Ex. 1001.5 = (5) 3. Zeros at the beginning of a number are NEVER significant • Ex. 0.0053 = (2) 4. Zeros after a number and after a decimal point are significant • Ex. 0.5600 = (4) 5. Zeros preceding an “imaginary” decimal and following a number are not significant • Ex. 1,000 = (1) (Mathematics of Sig Figs) 1. When adding or sub. #’s, your final answer an only be as precise as the number that is least precise, in decimals. • Ex. 2.445 + 2.3 = 4.745 = 4.7 1. When multiplying or dividing two #’s, your final answer an only contain as many sig figs as the factor with the least sig figs used to find it. • Ex. 2.565 (4 sig figs) * 8.30 (3 sig figs) = 21.2895 = 21.3 (3 sig figs)
 * • Addition/Subtraction Rules of Sig Figs**
 * • Multiplication/Division Rules of Sig Figs**

Determine the # of sig figs 1. 0.005400 *4 because the zeros after a number and decimal are significant 2. 93,000,000 *2 because the zeros are not significant 3. 105.0 *4 because the last zero is after a number and a decimal 4. 10.19 x 0.013 =.13 because you can only have 2 sig figs 5. 174/24 = 7.3 because you can only have 2 sig figs
 * Practice Problems**:

Metric System:
Kilo 1000 Hecto 100 Deka 10 Meter 1 Deci .1 Centi .01 Milli .001

Will a tablecloth that is 155 cm long cover a table that is 1.6 meters long?
 * Practice Problems:**

155cm = 1.55m No, it's not quite long enough, it is .005m short

Scientific Notation:
Rules: # must be between 1-10 and you multiply it by 10 to the power of x (however many times you have to move the decimal place)

Practice Problems: 0.00212 x 10^12 = 2.12 x 10^9 9204 x 10^5 = 9.204 x 10^8

1. Chance each number so that the powers of 10 match. a. Ex. 2.51 x 10^4 m + 1.61 x 10^3m is changed to 2.51 x 10^4m + .161 x 10^4m 2. Add of subtract the numbers 3. Attach the power of ten to your answer along with the units 4. If your addition or subtraction gives you a number larger than 10 or smaller than one, adjust your power of 10 accordingly.
 * Adding & Subtracting in Scientific Notation**

6.2 x 10^-4 + 5.7 x 10 ^-3 = 6.32 x 10^-3 because to add, they have to have the same exponent
 * Practice Problems:**

**Multiplying and Dividing**
1. Multiply or divide the numbers as told 2. When multiplying, add the powers of 10 When dividing, subtract the powers of 10 3. Adjust the power of 10 to be in proper scientific form a. Ex: (2.3 x 10^3 m) (5,7 x 10^4) 2.3 x 5.7 = 13.11 10 ^3 x 10^4 = 10^7

Density:
Formula: d=m/v d=g/ml (liquid) d=g/cm3 (solid)
 * less density allows objects to float (density of water: 1.00g/ml 1ml=1 cm^3

Factor Labeling:
Step 1. Show what you are given on the left, and what units you want on the right.

Step 2. Insert the required conversion factors to change between units. In this case we need only one conversion factor, and we show it as the fraction, 1hr/60min. We put the units of minutes on the bottom so that they will cancel out with the minutes on the top of the given.

Step 3. Cancel units where you can, and solve the math.

Of course, most of us can do the above calculation in our heads. This is because we are very familiar with the units and the conversion factors involved. Not all conversions will be that easy, but if you follow the steps correctly, there should be little chance for mistake. Follow the example below. Example 1. A student determines that the density of a certain material is 4.46 g/cm3. What would be the density of this material in g/L? Well, in order to solve this problem you must remember that 1000 cm3 = 1L. Then follow the same steps as the previous problem. Step 1. Show what you are given on the left, and what units you want on the right.

Step 2. Insert the required conversion factors to change between units. Note that I have changed the "look" of the fractions to show the cancellation of units more clearly.

Step 3. Cancel units where you can, and solve the math.

Answer - 4460 g/L (note that we are showing the correct number of significant digits.) Example 2. Imagine that water is leaking from a container, at a rate of 1.2 ml/hour. If this rate does not change, how many liters of water will be lost in a week? We can make a list of the conversion factors that we will need. 1 L = 1000 ml 24 h = 1 day 7 day = 1 week

Step 1. Show what you are given on the left, and what units you want on the right.

Step 2. Insert the required conversion factors to change between units.

Step 3. Cancel units where you can, and solve the math.

We must round to two significant digits, as shown in the original problem. Answer - 0.20 L/week

3.441 x 10^20 molecules / 1 x 1 mol / 6.022 x 10^23 molecules x 41.9882 grams / 1 mol = .02399 grams
 * Practice Problems:**

Example taken from: http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson24.htm