H Chem Moles Test

equations and sig fig rules refresh

a MOLE of any substance contains Avogradro’s number which is

6.022 × 10²³

GRAMS to MOLES

grams × (1 mol / molar mass)

MOLES to GRAMS

moles × (molar mass / 1 mol)

MOLES to PARTICLES

moles × (Avogadro’s # / 1 mol)

PARTICLES to MOLES

particles × (1 mol / Avogadro’s #)

GRAMS to PARTICLES

grams × (1 mol / molar mass) × (Avogadro’s # / 1 mol)

PARTICLES to GRAMS

particles × (1 mol / Avogadro’s #) × (molar mass / 1 mol)

how do you find the EMPIRICAL FORMULA?

grams → moles → divide by smallest → whole numbers

MOLARITY

(moles of solute/liters of solute)

• mol/L

*find moles of compound

HYDRATE FORMULA

find water mass → grams → moles (both) → divide by smallest

(mass lost due to heating is mass of the water x-y, mass left after heating is the mass of the compound)

how many sig figs?

1432

4- all NON-ZEROES ARE significant

how many sig figs?

1003

4- zeroes that are BETWEEN significant figures ARE significant

how many sig figs?

0.0006

1- zeroes that START a number are NOT significant (they are place holders)

how many sig figs?

33.30

4- zeroes at the END of a number (very right) AND after a decimal ARE significant

3500

2- zeroes at the END of a number with NO explicit decimal point are NOT significant