1 gram mixture of nahco3 and na2co3 is heated to 150 c .the volume of the co2 produced at stp is 112ml . The percentage of na2co3 in the mixture is
Answers
Explanation:
When you heat a mixture of
Na
2
CO
3
and
NaHCO
3
, only the
NaHCO
3
decomposes.
The equation for the decomposition is
2NaHCO
3
(
s
)
→
Na
2
CO
3
(
s
)
+
CO
2
(
g
)
+
H
2
O
(
g
)
The loss in mass is caused by the loss of
H
2
O
and
CO
2
(equivalent to the loss of
H
2
CO
3
).
The loss in mass is
(220 – 182) g = 38 g
.
This corresponds to
38
g H
2
CO
3
×
1 mol H
2
CO
3
62.02
g H
2
CO
3
=
0.613 mol H
2
CO
3
∴
Moles of NaHCO
3
=
0.613
mol H
2
CO
3
×
2 mol NaHCO
3
1
mol H
2
CO
3
=
1.225 mol NaHCO
3
and
Mass of NaHCO
3
=
1.2225
mol NaHCO
3
×
84.01 g NaHCO
3
1
mol NaHCO
3
=
102.9 g NaHCO
3
.
The loss of mass after heating corresponds to
102.9 g of original NaHCO
3
.
The rest of the original mixture must have been
Na
2
CO
3
.
Mass of original Na
2
CO
3
=
220 g – 102.9 g
=
117.1 g
% Na
2
CO
3
=
117.1
g
220
g
×
100
%
=
53.2 %
%
NaHCO
3
=
102.9
g
220
g
×
100
%
=
46.8
%