Ch. 2 Math Review

Scientific Notation Scientific Notation: a method for

__________________________________________.Moving the decimal to the

_______________exponent, to the _________________________________________.

Ex. 0.00527g = 5.27 x 10-3 g52700000 m = 5.27 x 107 m

3.25 x 10-6 cm3 = 0.00000325 cm3

3.25 x 104 cm3 = 32500cm3

2-2

Scientific NotationPractice:

1) 0.000060731 ml =

2) 2.970 x 10-5 mg =

3) 546901000 kg =

4) 6.3 x 107 s =2-3

Rounding Atomic MassesRounding Atomic Masses: we will be

rounding the atomic masses off the periodic table to the __________________________________________

Ex. C = 12.011 g/mol = 12.01 g/mol

Bi = 208.98038 g/mol = 208.98 g/mol

K = 39.0983 g/mol = 39.10 g/mol

Rounding Atomic MassesPractice:

5) N = 14.00674 g/mol =

6) Si = 28.0855 g/mol =

7) O = 15.9994 g/mol =

8) Ar = 39.948 g/mol = 2-5

Significant Figures Non zeros are always ____________________. Zeros _____________________are significant. Leading and trailing zeros

___________________________________.Atlantic/Pacific Rule:

Pacific: Point Present, start from the left, first nonzero and everything after is significant

Atlantic: Point Absent, start from the right, first nonzero and everything after is significant.

Significant Figures Ex. 1200 = 2 sig figs 0.003 = 1 sig fig

1.200 = 4 sig figs 0.0030 = 2 sig figs

Practice:9) 1.2650 = 10) 325000 =

11)1.280 x 10-1 = 12) 31006 =

2-7

Significant FiguresRounding Calculations According to Sig Figs

Addition and Subtraction: Round answers to the _____________________________________________:

Ex. 2.2 6.9801 + 5.67 - 4.21

7.87 = 7.9 2.7701 = 2.77

2-8

Significant FiguresPractice:

13)4.71 - 1.1

14)5.367 + 1.2

2-9

Significant FiguresMultiplication and Division: Round answers

to the _______________________________________________________________________________________:

Ex. 2.60 x 300 = 780 = 80052.31 x 2600 = 136006 = 140000

2000000 ÷ 5.63 = 355239.7869 = 4000000 78 ÷ 6 =13 = 10

2-10

Significant Figures Practice:15)240. ÷ 6.0 =

16) 365 ÷ 5 =

17)32 ÷ 3 =

18)32 x 3.0 = 2-11

Dimensional AnalysisUsed to convert between units. Take an equivalent (12 in. = 1 ft.) and make it into a __________________:

1 ft. or 12 in.12 in. 1 ft.

Use conversion factors to convert between units. _______________________________________________and multiply by the conversion factor with _____________________________________________. (so they cancel)

2-12

Dimensional Analysis Ex. 5.36 ft. = ? in.

5.36 ft. x 12 in. = 64.32 in. = 64.3 in. 1 ft.

32 in. = ? ft.

32 in. x 1 ft. = 2.666 ft. = 2.7 ft. 12 in.

12-13

Dimensional Analysis Ex. 3.26 in. = ? cm

3.26 in. x 1 cm= 8.280416561 cm = 8.28 cm 0.3970 in.

25 g = ? kg just use your handout, move your decimal 3 places to the left 25 g = 0.025 kg

5.69 oz. = ? g5.69 oz. x 28.3 g= 161.027 g = 161 g 1 oz.

Dimensional Analysis Ex. 1 year = ? S

1 year x 365 days x 24 hours x 60 min. X 60 s =

1 yr. 1 day 1 hr. 1 min.

= 31536000 s = 30000000 s

12-15