Front

What is Avogadro's number?

Back

Avogadro's number is 6.022 x 10^23 molecules, which is the number of atoms, ions, or molecules in one mole of a substance.

Front

What is the empirical formula for a compound that is 30.4% nitrogen and 69.6% oxygen?

Back

The empirical formula is NO2.

Front

Which pair has the same empirical formula?

Back

C2H4O2 and C6H12O6 have the same empirical formula.

Front

What is the percent composition of fluorine in CaF2 (gram-formula mass = 78 g/mol)?

Back

The percent composition of fluorine in CaF2 is 49%.

Front

Determine the gram-formula mass of H2O.

Back

The gram-formula mass of H2O is 18 g/mol.

Front

Define empirical formula.

Back

An empirical formula is the simplest whole-number ratio of atoms of each element in a compound.

Front

What is the formula to calculate percent composition?

Back

Percent composition = (mass of element in 1 mole of compound / mass of 1 mole of compound) x 100%.

Front

What is the significance of Avogadro's number in chemistry?

Back

Avogadro's number allows chemists to convert between the number of atoms/molecules and the amount of substance in moles.

Front

How do you find the empirical formula from percent composition?

Back

Convert the percentages to grams, then to moles, and divide by the smallest number of moles to find the ratio.

Front

What is the difference between empirical and molecular formulas?

Back

The empirical formula shows the simplest ratio of elements, while the molecular formula shows the actual number of atoms in a molecule.