8
You visited us
8
times! Enjoying our articles?
Unlock Full Access!
Byju's Answer
Standard XII
Chemistry
Molality
Presence of ...
Question
Presence of
C
a
S
O
4
causes permanent hardness in water. It can be removed by precipitating it as
C
a
C
O
3
by adding
N
a
2
C
O
3
. If the amount of
N
a
2
C
O
3
required to soften 100 L of hard water, which is 200 ppm
C
a
C
O
3
, is
x
g, then value of
x
is:
Open in App
Solution
N
a
2
C
O
3
106
g
+
C
a
S
O
4
→
C
a
C
O
3
100
g
↓
+
N
a
2
S
O
4
10
6
m
L
o
f
h
a
r
d
w
a
t
e
r
h
a
s
=
200
g
C
a
C
O
3
100
L
=
10
5
m
L
o
f
h
a
r
d
w
a
t
e
r
h
a
s
=
20
g
C
a
C
O
3
I
f
h
a
r
d
n
e
s
s
i
s
100
g
,
N
a
2
C
O
3
r
e
q
u
i
r
e
d
=
106
g
I
f
h
a
r
d
n
e
s
s
i
s
20
g
,
N
a
2
C
O
3
r
e
q
u
i
r
e
d
=
21.2
g
Suggest Corrections
0
Similar questions
Q.
Permanent hardness is due to
S
O
2
−
4
and
C
l
−
of
C
a
2
+
and
M
g
2
+
and is removed by the addition of
N
a
2
C
O
3
.
C
a
S
O
4
+
N
a
2
C
O
3
⟶
C
a
C
O
3
+
N
a
2
S
O
4
C
a
C
l
2
+
N
a
2
C
O
3
⟶
C
a
C
O
3
+
2
N
a
C
l
If hardness is
100
ppm
C
a
C
O
3
, amount of
N
a
2
C
O
3
required to soften
10
L of hard water is
:
Q.
Permanent hardness is due to
C
l
⊝
and
S
O
2
−
4
of
M
g
2
+
and
C
a
2
+
and is removed by adding
N
a
2
C
O
3
.
C
a
S
O
4
+
N
a
2
C
O
3
→
C
a
C
O
3
+
N
a
2
S
O
4
C
a
C
l
2
+
N
a
2
C
O
3
→
C
a
C
O
3
+
2
N
a
C
l
Which of the following statements is/are correct?
Q.
N
a
2
C
O
3
is widely used in softening of hard water. If 1 L of hard water required
0.0106
g
of
N
a
2
C
O
3
, The hardness in ppm (parts per million i.e.,
10
6
ml) of
C
a
C
O
3
is:
Q.
Following reaction is used to remove temporary hardness which is due to dissolved bicarbonates of
C
a
2
+
and
M
g
2
+
.
C
a
(
H
C
O
3
)
2
+
C
a
(
O
H
)
2
→
2
C
a
C
O
3
↓
+
2
H
2
O
Actually lime (
C
a
O
) is added which in
H
2
O
forms
C
a
(
O
H
)
2
and precipitates
C
a
C
O
3
C
a
O
+
H
2
O
→
C
a
(
O
H
)
2
If
10
L of hard water requires
0.56
g of
C
a
O
, temporary hardness of
C
a
C
O
3
is
x
×
10
2
ppm. Find
x
.
Q.
Hardness of water is measured in terms of ppm (parts per million) of
C
a
C
O
3
. It is the amount (in g) of
C
a
C
O
3
present in
10
6
g
H
2
O
. In a sample of water,
10
L required
0.56
g of
C
a
O
to the remove temporary hardness of
H
C
O
−
3
.
C
a
(
H
C
O
3
)
2
+
C
a
O
⟶
2
C
a
C
O
3
+
H
2
O
Temporary hardness is
:
View More
Join BYJU'S Learning Program
Grade/Exam
1st Grade
2nd Grade
3rd Grade
4th Grade
5th Grade
6th grade
7th grade
8th Grade
9th Grade
10th Grade
11th Grade
12th Grade
Submit
Related Videos
Reactions in Solutions
CHEMISTRY
Watch in App
Explore more
Molality
Standard XII Chemistry
Join BYJU'S Learning Program
Grade/Exam
1st Grade
2nd Grade
3rd Grade
4th Grade
5th Grade
6th grade
7th grade
8th Grade
9th Grade
10th Grade
11th Grade
12th Grade
Submit
AI Tutor
Textbooks
Question Papers
Install app