Chemistry Reference
In-Depth Information
2.
[0.778 g of O
2
]—
2Mg
(s)
+ O
2(g)
2MgO
(s)
1.18 g
x g
mass
molar mass
1.18 g
24.3 g/mole
# of moles of MgO =
=
= 0.0486 moles
A.
B. # of moles of O
2
can be found with the molar ratio:
Mg
O
2
coefficients
# of moles
2
0.0486
1
x
=
# of moles of O
2
(x) = 0.0243 moles
C. Mass of O
2
= # of moles × molar mass = 0.0243 moles × 32.0 g/mole = 0.778 g
3.
[1.45 g of MgO]—
2Mg
(s)
+ O
2(g)
2MgO
(s)
0.875 g
x g
mass
molar mass
0.875 g
24.3 g/mole
A.
# of moles of Mg =
=
= 0.0360 moles
B. # of moles of MgO can be found with the molar ratio:
Mg
MgO
coefficients
# of moles
2
0.0360
2
x
=
# of moles of MgO (x) = 0.0360 moles
C. Mass of MgO = # of moles × molar mass = 0.0360 moles × 40.3 g/mole =1.45 g
4.
[1.52 g of KCl]—
2KClO
3
KCl + 3O
2
5.00 g
x g
mass
molar mass
5.00 g
123 g/mole
A.
# of moles of KClO
3
=
=
= 0.0407 moles
B. # of moles of KCl can be found with the molar ratio:
KClO
3
KCl
coefficients
2
0.0407
1
x
# of moles
=
# of moles of KCl (x) = 0.0204 moles
C. Mass of KCl = # of moles × molar mass = 0.0204 moles × 74.6 g/mole = 1.52 g
5.
[7.69 g of KClO
3
]—
2KClO
3
KCl + 3O
2
x g
3.00 g
mass
molar mass
3.00 g
32.0 g/mole
A.
# of moles of O
2
=
=
= 0.0938 moles
B. # of moles of KClO
3
can be found with the molar ratio:
KClO
3
O
2
coefficients
# of moles
2
x
3
0.0938
=
# of moles of KClO
3
(x) = 0.0625 moles
C. Mass of KClO
3
= # of moles × molar mass = 0.0625 moles × 123 g/mole = 7.69 g
6.
[63.0 g of O
2
]—
2KClO
3
KCl + 3O
2
49.0 g
x g
mass
molar mass
49.0 g
74.6 g/mole
A.
# of moles of KCl =
=
= 0.657 moles
