Question 1

What is stoichiometry?

Accepted Answer

Stoichiometry is the part of chemistry that calculates the quantities of reactants and products in chemical reactions. It uses the mole concept and balanced equations to convert between mass, moles and number of particles.

Question 2

How do I convert grams to moles?

Accepted Answer

Divide the mass in grams by the molar mass of the substance in g/mol. Moles = mass (g) ÷ molar mass (g/mol). For example, 36 g of water (molar mass 18.015 g/mol) equals about 2 moles.

Question 3

What is Avogadro's number?

Accepted Answer

Avogadro's number is 6.022 × 10²³ particles per mole. One mole of any substance contains exactly this many atoms, molecules or formula units.

Question 4

How are molecules and atoms different here?

Accepted Answer

Molecules (or formula units) count the whole chemical units. Atoms counts every individual atom, which equals molecules multiplied by the total number of atoms in one formula unit. For H2O, 1 molecule contains 3 atoms.