Chemistry

Calculations

1. Rounding

Examples

*0.1356 (4 significant figures) -> Round answer to 2 significant figures *0.1356 -> 0.14

*314.705 (6 significant figures) -> Round number to 4 significant figures.
*314.705 -> 314.7

*0.0035771 (5 significant figures) -> Round to 3 significant figures.
*0.0035771 -> 0.00358

*500,000 (1 significant figure) -> Write this number to have 3 significant figures.
*500,000 - 5.00 x 10^5

*39.501 -> Round to 2 significant figures.
*39,501 -> 4.0 x 10

*0.054961 -> Round to 3 significant figures.
*0.054961 -> 5.50 x 10^-2 or 0.0550

2. Addition and Subtraction

*The answer is rounded to the same number of decimal places as the number with the least number of decimal places.

Examples

*5.10 + 3.9 = 9.0

*153.14 + 75.099 = 228.239 -> 228.24 FINAL ROUNDED ANSWER

*150.15 - 87.991 = 62.159 -> 62.16 FINAL ROUNDED ANSWER

3. Multiplication and Division

*The answer is rounded to the same number of significant figures as the number with the least number of significant figures.

Examples

*2.8 (2 sig figs) x 1.05 (3 sig figs) = 2.94 -> 2.9 FINAL ROUNDED ANSWER.

*1.75 (3 sig figs) x 35.01(4 sig figs) = 61.2675 -> 61.3 FINAL ROUNDED ANSWER.

Units

*S.I. Units used for LENGTH, MASS, VOLUME, TEMPERATURE, AMOUNT OF SUBSTANCE, and TIME.

*Length - meter (m)
*Mass - kilogram (kg)
*Volume - liter (l)
*Temperature - Kelvin (K)
*Amount of Substance - Mole (mol)
*Time - seconds (s)

Prefixes

*n - (nano) -> Meaning -> 10^-9. Nanometer (nm) = 10^-9m
*M (Micro) -> Meaning -> 10^-6
*m (milli) -> Meaning -> 10^-3
*c (centi) -> Meaning -> 10^-2
*d (deci) -> Meaning -> 10^-1
*K (kilo) -> Meaning -> 10^3
*M (mega) -> Meaning -> 10^6

Example for homework.

5m x 2m = 10m^2
Cj Apellanes

Mr. Dalton

American Literature

March 26th, 2013

"A Boy, A Snake, and an Angel." by Henry Hurt (Study Questions)

1. Mark Durrance is described as a handsome boy, with