In: Chemistry
a). Calculate the molar mass in g/mol of the following compound (ammonium dichromate):
(NH4)2Cr2O7
b). Calculate the mass, in g, of the following: 0.158 mol IF5 (iodine pentafluoride)
c). Calculate the amount, in moles, of the following: 25.4 g Pb(C2H3O2)2 (lead (II) acetate)
Professors Note: Make sure that you give your answer in a clear and well-reasoned manner, providing necessary explanation on how did you come up with it.
d). Calculate the percent by mass of C, H, and O in C6H12O6 (glucose )
solution:
a). Calculate the molar mass in g/mol of the following compound (ammonium dichromate):
(NH4)2Cr2O7
Lets calculate individual mass of atoms;
2 X N = 2 X 14 = 28
8 X H = 8 X 1 = 8
2 X Cr = 2 X 52 = 104
7 X O = 7 X 14 = 112
Molar mass of (NH4)2Cr2O7 = 28 + 8 + 104 + 112 = 252.0 g/mol
Molar mass of (NH4)2Cr2O7 = 252.0 g/mol
b). Calculate the mass, in g, of the following: 0.158 mol IF5 (iodine pentafluoride)
Solution:
# of mole = 0.158 mol
We know
# of mole = mass in g/molar mass.
(molar mass of IF5 = 221.89 g/mol)
mass in g = # of mole X molar mass = 0.158 mol X 221.89 g/mol
= 35.05 g.
Mass of 0.158 mol IF5 = 35.05 g
c). Calculate the amount, in moles, of the following: 25.4 g Pb(C2H3O2)2 (lead (II) acetate)
Professors Note: Make sure that you give your answer in a clear and well-reasoned manner, providing necessary explanation on how did you come up with it.
Given:
Mass = 25.4 g.
Molar mass = 325.28 g/mol
We know
# of mole = mass in g/molar mass =25.4 g/325.28 g/mol
# of mole = 0.0780 mol.
25.4 g Pb(C2H3O2)2 (lead (II) acetate) mole require =0.0780 mol
d). Calculate the percent by mass of C, H, and O in C6H12O6 (glucose )
Solution:
mass of C6H12O6 = 180.0 g/mol
%mass of c = (mass of C in C6H12O6 / total mass of C6H12O6)X100%
= (72/180.0) X 100% = 40.0%
%mass of c = 40.0% C in C6H12O6
Mass of H = (mass of H in C6H12O6 / total mass of C6H12O6)X100%
= (12/180) x 100% = 6.66%
%mass of H = 6.66% H in C6H12O6
Mass of O = (mass of O in C6H12O6 / total mass of C6H12O6)X100%
= (96/180) x 100% = 53.33%
%mass of O = 53.33% O in C6H12O6