Molar Mass (M) Topic 1.2

Mass relative atomic mass (Ar) all masses on the periodic table are compared to CARBON- 12 no units are necessary since it is just a comparison to carbon- 12 from this we get the average atomic mass that you would find for an element on the periodic table

relative molecular mass (Mr) simply comparing a given molecule to carbon CO2 is 44. C60 is 720, O2 is 16(2) = 32 atomic or molecular mass this is simply the mass of one atom or molecule using a very small unit of measurement called a.m.u. therefore CO2 is 44 a.m.u. molar mass (M) this is how many grams you would have in a mole of a substance therefore CO2 is 44 g/mol

molar mass continued… simply change the relative atomic mass from the periodic table for the element/molecule/ compound to grams oxygen’s atomic mass is 16.00 amu therefore 1 mole of oxygen has a molar mass is 16.00 g/mol sugar’s (C6H12O6) atomic mass is 180.0 amu carbon: 12.00(6) = 72.00 hydrogen: 1.00(12) = 12.00 oxygen: 16.00(6) = 96.00 therefore 1 mole of sugar has a molar mass of 180.00 g/mol

Calculate the Molar Mass of Na3PO4. Atom # Atomic Mass Total Na 3 X 23.0 = 69.0 P 1 X 31.0 31.0 O 4 X 16.0 64.0 164.0 Therefore the molar mass is 164.0 g mol-1

Give the molar mass (mass of one mole): Fe → 55.9 g/mol C2H6 → 30.1 g/mol Fe(OH)2 → 89.9 g/mol C12H22O11 → 342.3 g/mol CuSO4 · 5 H2O → 238 g/mol

Converting Moles to Grams and Grams to Moles conversion factor will be: 1 mole molar mass OR molar mass__

Number of moles to mass(g) Find the mass (in grams) of 1.93 moles of MgO? 1.93 mol MgO x 40.3 g MgO 1 1 mol MgO = 77.8 g MgO Mass(g) to moles Find the number of moles in 23.5 g of MgO? 23.5 g MgO x 1 mole MgO 1 40.3 g MgO = 0.583 mol MgO

Number of grams to moles to particles Find the number of particles in 13.9 g of MgO? 13.9 g MgO x 1 mole MgO_ x _6.02 X 1023 particles MgO 1 40.3 g MgO 1 mole MgO 1 mole MgO_ x _6.02 X 1023 particles MgO 40.3 g MgO 1 mole MgO 6.02 X 1023 particles MgO 40.3 g MgO molar mass (g) = 2.07 X 1023 particles of MgO here it is again combining two conversion factors same thing but be careful if you do this!

What is the mass of 2.55 × 1023 atoms of lead? 2.55 × 1023 atoms Pb × 1 mol Pb 6.02×1023 atoms Pb 207.2 g Pb 1 mole Pb × = 87.8 g Pb

How many atoms in 22 grams of copper?

The Mole Road Map “Stuff” Mass Mole Volume Stuff: Atoms Molecules 6.022 x 1023 mole mole g Stuff: Atoms Molecules Particles Electrons Ions Formula Units Mole g mole mole . 6.022 x 1023 22.7 L mole mole . 22.7 L For Gases only: @ STP (Standard Temp & Pressure) (0 oC (273 K) & 1 atm) Volume