chem final is stupid Cheat Sheet (DRAFT) by ChemIsForSheeit

To determine the number of signif­­icant figures in a number use the following 3 rules:

1.Non-zero digits are always signif­­icant

2.Any zeros between two signif­­icant digits are signif­­icant

3.A final zero or trailing zeros in the decimal portion ONLY are signif­­icant

Example: .500 or .632000 the zeros are signif­­icant

.006 or .000968 the zeros are NOT signif­­icant

For addition and subtra­­ction use the following rules:

1.Count the number of signif­­icant figures in the decimal portion ONLY of each number in the problem

2.Add or subtract in the normal fashion

3.Your final answer may have no more signif­­icant figures to the right of the decimal than the LEAST number of signif­­icant figures in any number in the problem.

For multip­­li­c­ation and division use the following rule:

1.The LEAST number of signif­­icant figures in any number of the problem determines the number of signif­­icant figures in the answer. (You are now looking at the entire number, not just the decimal portion)
This means you have to be able to recognize signif­­icant figures in order to use this rule

Example: 5.26 has 3 signif­­icant figures

6.1 has 2 signif­­icant figures

#unit¹ x #unit (­con­­verting to) / #unit¹

#=number

cancel like units

then multiply and divide then you get your answer with new units

PV/nT=­nRT/nT

P=atm
V=L liters?
n=# of mols
T=Kelvin
R= 0.0821 atm x L / mol x K ---Always divide the numbers underneath

Atmosp­­he­r­e-atm
Bar-Bar
millimeter of mercur­­y-mmHg
Pascal-pa
Pounds per square inch-psi
Torr-torr

1s
2s 2p
3s 3p 3d
4s 4p 4d 4f
5s 5p 5d 5f
6s 6p 6d 6f
7s 7p 7d 7f

s=2 p=6 d=10 f=14