Molar Mass Chemistry 11 Ms. McGrath

Molar Mass Molar mass (M) is the mass of one mole (6.02 x 1023 particles) of a substance numerically equal to the element’s average atomic mass (u). It is expressed as g / mol.

Molar Mass Molar masses of common chemical compounds that you might find in the chemistry laboratory can range between 18 grams/mole for compounds like water to hundreds of grams per mole for more complex chemical compounds.

Molar Mass The lightest possible chemical that one can have under normal conditions is hydrogen gas, or H2. There is no limit to how heavy a chemical compound can be - it is not uncommon for macromolecules (large organic or bioorganic compounds such as DNA) to weigh thousands of grams per mole.

Molar Mass How do I find Molar Mass? The molar mass of elements is found by looking at the atomic mass of the element on the periodic table. For example, if you want to find the molar mass of carbon, you would find the atomic mass of carbon on the periodic table, and this is equal to the molar mass in grams per mole. So, carbon has a molar mass of 12.01 g / mol.

Molar Mass How do I find Molar Mass? There are a few exceptions to this rule: In the case of H, N, O, F, Cl, Br, and I, the element is diatomic, meaning that each molecule of the element has two atoms of that element bonded together. P is normally found in clumps of four atoms, and S is found in clumps of eight atoms. Aside from the exceptions above, all elements have the same molar mass as the atomic masses on the periodic table.

Molar Mass How do I find Molar Mass? Molar masses of chemical compounds are equal to the sums of the atomic masses of all the atoms in one molecule of that compound. ex: BeO MBeO = 9.01 g/mol + 16.00 g/mol = 25.01 g/mol

Molar Mass How do I find Molar Mass? ex: Ca3(PO4)2 MCa x 3 = (40.08 g/mol) x 3 = 120.24 g/mol MP x 2 = (30.97 g/mol) x 2 = 61.94 g/mol MO x 8 = (16.00 g/mol) x 8 = 128.00 g/mol MCa3(PO4)2 = 120.24 g/mol + 61.94 g/mol + 128.00 g/mol = 310.18 g/mol

Molar Mass Practice - Molar Mass Page 57 #16, 17, 18, 19

Molar Mass Converting from Moles to Mass Mass = Number of moles x Molar Mass m = n x M

Molar Mass Converting from Moles to Mass A flask contains 0.750 mol of carbon dioxide gas, CO2. What mass of carbon dioxide gas is in this sample? m = n x M MCO2 = 2 x (16.00 g/mol) + 12.01 g/mol = 44.01 g / mol = (0.750 mol) x (44.01 g/mol) = 33.0 g

Molar Mass Practice - Converting from Moles to Mass Page 59 #20, 21, 22, 23

Molar Mass Converting from Mass to Moles Number of moles = mass Molar Mass n = m M

Molar Mass Converting from Mass to Moles How many moles of acetic acid, CH3COOH, are in a 23.6g sample? The molar mass of CH3COOH is: (12.01 x 2) + (16.00 x 2) + (1.01 x 4) = 60.06 g / mol n = m M = 23.6 g 60.06 g / mol = 0.393 mol

Molar Mass Converting from Mass to Moles Page 60 #24 - 27