10) You need to find the atomic mass of every element, which you can get from any periodic table.
a) 6.02x10^23 atoms of Mg
Atomic mass of Mg = 24.3 g/mol
# of mols = 6.02 x 10^23 atoms / 6.02 x 10^23 atoms/mol = 1 mol
mass = 1 mol x 24.3 g/mol = 24.3 g
b) 3.01x10^23 formula units of Ca Cl2
Atomic masses
Ca: 40 g/mol
Cl: 35.5 g/mol
Formula mass: 40g/mol + 2x 35.5g/mol = 111 g/mol
# of mols = 3.01 x 10^23 / 6.02 x 10^23 = 0.5 mol
mass = 0.5 mol x 111 g/mol = 55.5 g
c) 12.4 x 10^15 molecules of CH2O
formula mass = 12 g/ mol + 2 g/mol + 16 g/mol = 30 g/mol
# of mols
mass = [12.4 x 10^15 / 6.02 x 10^23]mol x 30 g/mol = 2.1 x 10 ^(-8) g
3)
a) The polar solute is dissolved in water which is a polar solvent, while the non polar solute is not dissolved in water. This is a rule in chemistry: polar solvents dissovle polar soultes and non polar solvents dissolve non polar soluted.
The extremes of the polar molecules are easily solvated by the water molecules.
b) KI is an ionic compound, which implies that it will ioinize (separare in iones) in water, being in this way be dissolved, while the CO2, which is no polar, will not be easily dissolved in water under normal conditions
