1.25 gram of metal reacts with oxygen completely to produce 1.6 gram of metal oxide empirical formula of metal oxide is
Answers
Answer:
Answer:
The empirical formula is
Cr
2
O
3
.
Explanation:
The empirical formula is the simplest whole-number ratio of atoms in a compound.
The ratio of atoms is the same as the ratio of moles. So our job is to calculate the molar ratio of
Cr
to
O
.
Mass of Cr = 7.35 g
Mass of chromium oxide = mass of Cr + mass of O
10.74 g = 7.35 g + mass of O
Mass of O = (10.74 – 7.35) g = 3.39 g
Moles of Cr
=
7.35
g Cr
×
1 mol Cr
52.00
g Mg
=
0.1413 mol Mg
Moles of O
=
3.39
g O
×
1 mol O
16.00
g O
=
0.2119 mol O
To get this into an integer ratio, we divide both numerator and denominator by the smaller value.
From this point on, I like to summarize the calculations in a table.
Element
M
g
Mass/g
X
Moles
X
l
l
Ratio
m
m
×2
m
l
l
Integers
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
−
—
—
m
Cr
X
X
X
m
7.35
X
m
0.1413
X
l
l
1
X
m
m
m
2
m
m
m
m
l
2
m
O
X
X
X
X
l
3.39
m
m
0.2119
X
l
l
1.499
X
X
2.998
m
m
l
3
There are 2 mol of
Cr
for 3 mol of
O
.
The empirical formula of chromium oxide is
Cr
2
O
3
.