Density and Moles

MOLE UNIT CONVERTIONS CHART

Density--(D= M/V)--Mass--(molar mass)--Moles--(6.02 x 10^23)--Molecules
Mass--( x 22.4 L)--Volume(@STP)
Molecules--( x subscripts)--Atoms

Density --> mass per unit volume

D=M/V, M= D x V, V= M/D


Density of gasses at STP
1 mol of gas
D= M = Molar mass g/mol
V 22.4 L/mol

Calculate the density of O2 at STP
D= 32 g/mol = 1.43 g/L
22.4 L/ mol

Density of C2 at STP
D = 24 g/mol = 1.07 g/L
22.4 L/ mol

Cl2 --> DSTP
DSTP = mm = 71.0 g/mol = 3.17 g/L
22.4 L/mol

A mystery gas has a density of 1.696 g/L at STP
It is a diatomic element. Identify the gas.
MM= (1.696 g/L)(22.4 L/mol) = 38.0 g/mol (19 g/mol à fluorine)

The density of Boron(s) is 2.34 g/mL. How many molecules are in a 60.0 mL piece?
2.34g x 60.0 mL = 140.4g
1 mL
140.4 g x 1mol = 13 mol
10.8 g
13 mol x 6.02 x 1023 molec. = 7.83 x 1024 molecules
1 mol

Liquid mercury has a density of 13.55 g/mL
Find the volume occupied by 1.806 x 1027 atoms of H g
1.806 x 1027 molecules x 1 mol x 200.6 g = 601800 g
6.02 x 1023 molecules 1 mol
V = M = 601800 g = 44413 mL = 44.4 L
D 13.55 g/mL

A 5.00 mL(volume) sample of lead contains 0.274 mol (moles) of Pb(s).
Calculate the density of Pb.
Molà massà density
0.274 mol x 207.2 g = 56.7728 g
1 mol
D = M = 56.7728 = 11.35 g/mL
V 5.00 mL

Density of gaseous mixture of C8 H18 at STP
(C8x12 = 96) + (H18x1 = 18) = 114 g/mol
114 g/mol = 5.09 g/L
22.4 L/mol