STAAR Chemistry Reference Materials

Atomic Structure
Speed of light = (frequency)(wavelength) -- c = f(upside down y)

Energy = (Planck's constant)(frequency) -- E,,photon,, = hf

Energy = (Planck's constant)(speed of light)/wavelength) -- E,,photon,, = hc/(upside down y)

Behavior of Gases
Total pressure of a gas = (sum of the partial pressures of the component gases) -- P,,T,, = P,,1,, + P,,2,, + P,,3,,

(Pressure)(volume) = (moles)(ideal gas constant)(temperature) PV = nRT

(Initial pressure)(initial volume)/(Initial moles(initial temperature) = (final pressure)(final volume)/(final moles)(final temperature) -- P,,1,,V,,1,,/n,,1,,T,,1,, = P,,2,,V,,2,,/n,,2,,T,,2,,

(Initial pressure)(initial volume) = (final pressure)(final volume) -- P,,1,,V,,1,, = P,,2,,V,,2,,

(Initial volume)/(Initial temperature) = (final volume)/final temperature -- V,,1,,/n,,1,, = V,,2,,/n,,2,,

(Initial volume)/(Initial moles) = (final volume)/(final moles) -- V,,1,,/n,,1,, = V,,2,,/n,,2,,

Solutions
Molarity = moles of solute/liter of solution -- M = mol/L

Ionization constant of water = (hyrdogen ion concentration)(hyrdoxide ion concentration) -- K,,w,, = [H^+][OH^-]

(Volume of solution 1)(molarity of solution 1) = (volume of solution 2)(molarity of solution 2) -- V,,1,,M,,1,, = V,,2,,M,,2,,

pH = -logarithm (hydrogen ion concentration) pH = -log[H^+]

Thermochemistry
Heat gained or lost = (mass)(specific heat)(change in temperature) -- Q = mc,,p,,(change)T

Enthalpy of reaction = (enthalpy of products) - (enthalpy of reactants) -- (change)H = (change)Hof(products) - (change)Hof(reactants)

Other Formulas
Density = mass/volume -- D = m/v

Percent error = (accepted value - experimental value/accepted value)(100)

Percent yield = (actual yield/theoretical yield)(100)

Constants and Conversions
Avogadro's number = 6.02 x 10^23 particles per mole

h = Planck's constant = 6.63 x 10^-34 J * s

c = speed of light = 3.00 x 10^8 m/s

K,,w,, = ionization constant of water = 1.00 x 10^-14 (mol/L)^2

alpha particle (a) = 4/2He  beta particle (b) = 0/-1e   neutron = 1/0n

standard temperature and pressure (STP) = 0^degreesC and 1 atm

0^degreeC = 273 K

volume of ideal gas at STP = 22.4 L/mol

1 cm^3 = 1 mL = 1 cc

1 atm = 760 mm Hg = 101.3 kPa

R = ideal gas constant = 0.0821 L * atm/mol * K = 8.31 L*kPa/mol * K = 62.4 L* mm Hg/mol * K

1 calorie (cal) = 4.18 joules (J)

1000 calories (cal) = 1 Calorie (Cal) = 1 kilocalorie (kcal)

Rules for Significant Figures
1. Non-zero digits and zeros between non-zero digits are always significant.

2. Leading zeros are not significant.

3. Zeros to the right of all non-zero digits are only significant if a decimal point is show.

4. For values written in scientific notation, the digits in the coefficient are significant.

5. In a common logarithm, there are as many digits after the decimal point as there are significant figures in the original number.