19th Amendment Takes Effect - 1920 Lecture Homework: Reading Chapter 2, sections 6-10 Mastering Chemistry Assignment #1 DUE MONDAY PREREQUISITES!!!

How many Sig. Figs.? Two rules: #1) If there IS a decimal point in the number: Start at right of number and count until the LAST non-zero digit

2 3 . 2 8 1 . 6 8 1 . How many Sig. Figs.? 9 significant figures 2 8 1 9 significant figures . 6 8 4 significant figures 1 . 6 significant figures

How many Sig. Figs.? Two rules: #1) If there IS a decimal point in the number: Start at right of number and count until the LAST non-zero digit #2) If there is NOT a decimal point in the number Start at left of number and count until the LAST non-zero digit

7 4 2 9 3 2 3 8 1 How many Sig. Figs.? 5 significant figures 8 4 significant figures 1 1 significant figure

Significant Practice 60020300 12.00500 0.0005 0.10046 320000 8900. 0.0061000 0.1528 6 s.f. 7 s.f. 1 s.f. 5 s.f. 2 s.f. 4 s.f.

Rounding Numbers Find the last significant digit. If the next digit to the right is 4 or less, leave the last significant digit alone. If the next digit to the right is 5 or more, round the last significant digit up. Put large numbers into scientific notation BEFORE rounding

0.00259428 (3 s.f.) 0.00259428 (3 s.f.) = 0.00259 54.3675701 (5 s.f.) 54.3675701 (5 s.f.) = 54.368 8265391000 (2 s.f.) 8265391000 (2 s.f.) = 8300000000 0.659822 (3 s.f.) 0.659822 (3 s.f.) = 0.66 = 0.660 0.0005473300 (5 s.f.) 0.0005473300 (5 s.f.) = 0.00054733 617890100 (5 s.f.) 617890100 (5 s.f.) = 617890000

Sig. Figs. in Calculations Two rules: #1) Multiplication and Division The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer.

Calculations with Sig. Figs. Multiplication and division The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer. 1.5 x 7.3254 = 1 .9881 = 11 2 s.f. 5 s.f. 6.127 x 0.0000267030 = 0.000163 6 09 = 0.0001636 4 s.f. 6 s.f.

Calculations with Sig. Figs. 927.381 / 456.0 = 2.03 3 730263 = 2.034 6 s.f. 4 s.f. 0.00159 / 2 = 0.000 7 95 = 0.0008 3 s.f. 1 s.f. 6 s.f. 3 s.f. = 18 8 99522.37 = 18900000 4 s.f.

Some Practice 890.00 x 112.3 78132/2.50 0.0120 x 48.15 x 0.0087 500 x 0.000230012 99950 31300 0.0050 0.000000025 1900000 0.1

Sig. Figs. in Calculations Two rules: #1) Multiplication and Division: The value in the calculation that has the FEWEST number of sig. figs. determines the number of sig. figs. in your answer. #2) Addition and Subtraction: The value in the calculation that has the FEWEST decimal spots determines the number of decimal spots in your answer.

Adding and subtracting with sig. figs. 0.0025647 + 0.000321 7 decimal places 6 decimal places 0.0025647 0.0025647 +0.000321_ +0.000321_ 0.0028857 0.0028857 = 0.002886 answer can only be precise to the 6th decimal place

Adding and subtracting with sig. figs. 394.0150 + 0.0074121 4 decimal places 7 decimal places 394.0150 394.0150 + 0.0074121 + 0.0074121 394.0224121 394.0224121 = 394.0224 answer can only have 4 decimal places

Some More Practice 23.67 – 75 5502.8 + 24 + 0.01 0.109 + 0.09 – 0.955 20.4 + 1.322 + 78 -51 5527 -0.76 100.

Did you get it? 890.00 x 112.3 23.67 – 75 0.0120 x 48.15 x 0.0087 0.002411 – 0.4164 500 x 0.000230012

Did you get it? 890.00 x 112.3 23.67 – 75 0.0120 x 48.15 x 0.0087 99950 or 9.995x104 -51 0.0050

Did you get it? 0.002411 – 0.4164 500 x 0.000230012 2.5x10-8 -0.4140 0.1

Scientific Notation – Numbers > 1 Place a decimal so that there is a single digit to the left 1.8900000 18900000 Start counting from the right until you get to the decimal 1. 8 9 7 6 5 4 3 2 1 This becomes the exponent for “times 10 to the” 1.8900000x107 Remove digits from the right until proper # of sig. figs. 1.8900000x107 1.890000x107 1.89000x107 1.8900x107 1.890x107 1.89x107

Scientific Notation – Numbers > 1 Place a decimal so that there is a single digit to the left 7.16110 716110 Start counting from the right until you get to the decimal 7. 1 6 1 1 5 4 3 2 1 This becomes the exponent for “times 10 to the” 7.16110x105 Remove digits from the right until proper # of sig. figs. 7.16110x105 7.1611x105 7.1611x105

Scientific Notation – Numbers < 1 Start counting from the decimal point to the first non-zero digit. This will be the exponent in the “times ten to the negative” 0. 5 7022169 1 2 3 4 5 6 7 Move the decimal point to the right of the first non-zero digit, drop all of the leading zeros, and add the “times ten to the negative” with the exponent. 5.7022169x10-7

Scientific Notation – Numbers < 1 Start counting from the decimal point to the first non-zero digit. This will be the exponent in the “times ten to the negative” 0. 9 510 1 2 3 4 5 Move the decimal point to the right of the first non-zero digit, drop all of the leading zeros, and add the “times ten to the negative” with the exponent. 9.510x10-5

Did you get it? 512384000 4 s.f. 0.0006000 2 s.f. 0.00251634 5 s.f. 3540000000 5 s.f. 5.124x108 6.0x10-4 2.5163x10-3 3.5400x109

A Few Sig. Fig. Notes USUALLY, numbers with decimal points are MEASURED numbers What does this mean for sig. figs.? 1 is USUALLY a DEFINED number Put large numbers into scientific notation BEFORE rounding.

Types of Units (Quality Measured) Distance (length) foot, inch, mile, yard, meter, centimeter, rod Mass/Weight gram, kilogram, ton, pound, ounce, stone

Types of Units (Quality Measured) Volume gallon, quart, pint, milliliter, liter, cubic centimeter (cm3, cc) Time second, minute, hour, year, microsecond, eon

What quality is measured by…? kg mass oC temperature cm length/distance cm3 volume mL volume ft2 area

Dimensional Analysis (unit conversion) Unit equation 12 in = 12 in 1 ft _ 1 ft 1 ft _ = 1 = 12 in 12 in 12 in 12 in 12 in = 1 ft 1 ft 12 in = = 1 1 ft 1 ft 1 ft Conversion between feet and inches can be written either: 1 ft _ 12 in OR 12 in 1 ft These are called “Unit Factors”

Dimensional Analysis (unit conversion) The Goal: Convert one unit to another How: Use conversion factors Use them so that 1 ft _ 12 in OR 12 in 1 ft Unit you want to keep ____________________ Unit you want to cancel

Dimensional Analysis (unit conversion) How many feet are in 51.5 inches? 1 ft _ 12 in OR 12 in 1 ft

D.A. Practice I have a 100.0 fluid ounce CamelBak. How many gallons is my CamelBak?

D.A. Practice I have a 100.0 fluid ounce CamelBak. How many gallons is my CamelBak?

D.A. Practice If a person weighs 208 lbs, what is their mass in amu?