M
A sample contains 1.25 mol of nitrogen dioxide, NO2.
How many molecules are in the sample?
mol x (6.02 x 1023 molecules/mol) =
7.53 x 1023 molecules of nitrogen dioxide
State the molar mass of Ba.
MrBa = 137 g/mol
Calculate the number of moles in 56.3 mg of Ge.
100 mg = 1 g
n = m / Mr
n = 0.563 / 73
nGe = 7.71 x 10-3 mol
What is the value of Avogadro's number?
6.02 x 1023 particles
A small pin contains 0.0178 mol of iron, Fe.
How many atoms of iron are in the pin?
mol x (6.02 x 1023 atoms/mol) =
1.07 x 1022 atoms of iron
Calculate the mass of 3.90 mol of carbon, C.
n = m / Mr
m = n x Mr
m = 3.90 x 12
mc = 46.8 g
Which sample has the smallest mass?
A = 7.31 mol of O2
B = 5.64 mol of CH3OH
C = 12.1 mol of H2O
n = m / Mr
m = n x Mr
mA = 7.31 x (2x16) = 233.92 g
mB = 5.64 x (1x12+4x1+1x16) = 180.48 g
mC = 12.1 x (1x2+1x16) = 217.8 g
The name of the Italian chemist who postulated Avogadro's law: Equal volumes of gases, at equal temperature and pressures, contain the same number of molecules.
Amedeo Avogadro
How many formula units are contained in 0.21 mol of magnesium nitrate, Mg(NO3)2?
mol x (6.02 x 1023 formula units/mol) =
1.26 x 1023 formula units of Mg(NO3)2
Which sample has the largest mass?
A = 5.00 mol of C
B = 1.50 mol of Cl2
C = 0.50 mol of C6H12O6
n = m / Mr
m = n x Mr
mA = 5.00 x 12 = 60 g
mB = 1.50 x (35.5x2) = 106.5 g
mC = 0.50 x (6x12+12x1+6x16) = 90 g
Sodium chloride (NaCl) can be used to melt snow. How many moles of sodium chloride are in a 10000 g bag?
n = m / Mr
n = 10000 / (23+35.5)
nNaCl = 170.94 mol
The mass of one mole of a substance is known as ____________.
Consider a 0.829 mol sample of sodium sulfate, Na2SO4.
How many sodium ions, Na+, are in the sample?
mol x (6.02 x 1023 ions/mol) =
4.99 x 1023 sodium ions
Calculate the number of moles in 103 g of Mo.
n = m / Mr
n = 103 / 96
nMo = 1.07 mol
Strontium may be found in nature as celestite, SrSO4. Find the molar mass of celestite.
MrSrSO4 = (88+32+4x16)
MrSrSO4 = 184 g/mol
Determine the mass of 6.02 x 1024 formula units of ZnCl2.
Use the formula: n = N/NA
n = 6.02 x 1024 / 6.02 x 1023
nZnCl2 = 10 mol
n = m / Mr
m = n x Mr
m = 10 x (65+2x35.5)
mZnCl2 = 136 g