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Useful Constants and Formulas

Link to Periodic Table

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Table1. List of Constants

Avogadro’s number	6.02 x 10^23
Ideal gas constant	8.31 (kPa x L)/(K/mol)
Standard Temperature	0 °C or 273 K
Standard Pressure	101.3 kPa or 1 atm
STP Standard Temperature and Pressure	0 °C, 101.3 kPa

Table 2. Commonly Used Prefixes in the Metric System

Prefix	Symbol	Meaning	Factor	Sc. not.
mega	M	1 million times larger	1 000 000	10^6
kilo	k	1000 times larger	1 000	10^3
deci	d	10 times smaller	1/10	10^-1
centi	c	100 times smaller	1/100	10^-2
milli	m	1000 times smaller	1/1000	10^-3
micro	m	1 million times smaller	1/1 000 000	10^-6
nano	n	1000 million times smaller	1/1 000 000 000	10^-9
pico	p	1 trillion times smaller	1/1 000 000 000 000	10^-12

Table 3. Metric Units of Length

unit	Symbol	Relationship
kilometer	km	1 km = 10^3m
meter	m	base unit
decimeter	dm	10^1dm = 10 dm = 1 m
centimeter	cm	10^2 cm = 100 cm = 1 m
millimeter	mm	10^3 mm = 1000 mm = 1 m
micrometer	mm	10^6 mm = 1m
nanometer	nm	10^9 nm = 1 m

Table 4. Metric Units of Volume and Mass

Unit	Symbol	Relationship	Example
Liter	L	base unit	about 1 quart milk
milliliter	mL	10^3 mL = 1L	20 drops of water
cubic centimeter	cm^3	1 cm^3 = 1 mL	cube of sugar
microliter	mL	10^6 mL = 1L	crystal of table salt
kilogram	kg	base unit	2.2 lbs
gram	g	1 g = 10^-3kg	dollar bill
milligram	mg	10^3 mg = 1 g	ten grains of salt
microgram	mg	10^6 mg = 1g	particle of baking powder

Density is the ratio of the mass of an object to its volume Density = mass/ volume

Temperature

K = °C + 273, °C = K – 273 F =(9 x °C/5) + 32

absolute zero = 0 K = -273 °C

water boils at 100 °C and freezes at 0 °C (at standard atomospheric pressure)

Rules to Determine the Number of Significant Figures

Rules to Determine The Number of Significant Figures

1. Digits other than zero are always significant

61.4 g 3 significant digits

2. Zeros between two significant digits are always significant

306 m 3 significant digits

3. Zeros in front of nonzeros are not significant, they are used solely for spacing the decimal point (placeholder) 0.00783 g 3 significant digits

4. Zeros at the end of a number after the decimal points are always significant

4.7200 km 5 significant digits

5. Zeros at the right end of a number to the left of an understood decimal point are not significant (placeholders) 7000 g 1 significant digit

6. Unlimited numbers of significant figures:

Numbers that are counted instead of measured, e.g. 23 students is understood to be exact (cannot be 23.8 students) = 23.0000000000000000000000... , and exactly defined quantities, like mathematical constants or relations e.g. 60 min = 1 hr.

If 7000 g was accurately measured to the nearest gram, all four digits are significant. Correct: 7.000 x 10³.

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