Answer:
1.03 mol of dihydrogen gas will evolve, with a volume slightly over
22.4 
at STP.
Explanation:
<span>There are 2.74603 * 10^25 hydrogen atoms. Ammonium sulfide is represented by (NH4)2S. This means that there are 8 hydrogen atoms total. There are also 8 mol of H in ammonium sulfide. We also need to use avogadro’s number of 6.022 * 10^23.
Hydrogen Atoms = 5.7mol * (8mol / 1mol) * 6.022 * 10^23 per mol
Hydrogen atoms = 2.74603 * 10^25 hydrogen atoms.</span>
Answer: This is a typical acid/base equilibrium problem, that involves the use of logarithms.
Explanation:We assume that both nitric acid and hydrochloric acid dissociate to give stoichiometric
H
3
O
+
.
Moles of nitric acid:
26.0
×
10
−
3
⋅
L
×
8.00
⋅
m
o
l
⋅
L
−
1
=
0.208
⋅
m
o
l
H
N
O
3
(
a
q
)
.
And, moles of hydrochloric acid:
88.0
×
10
−
3
⋅
L
×
5.00
⋅
m
o
l
⋅
L
−
1
=
0.440
⋅
m
o
l
H
C
l
(
a
q
)
.
This molar quantity is diluted to
1.00
L
. Concentration in moles/Litre =
(
0.208
+
0.440
)
⋅
m
o
l
1
L
=
0.648
⋅
m
o
l
⋅
L
−
1
.
Now we know that water undergoes autoprotolysis:
H
2
O
(
l
)
⇌
H
+
+
O
H
−
. This is another equilibrium reaction, and the ion product
[
H
+
]
[
O
H
−
]
=
K
w
. This constant,
K
w
=
10
−
14
at
298
K
.
So
[
H
+
]
=
0.648
⋅
m
o
l
⋅
L
−
1
;
[
O
H
−
]
=
K
w
[
H
+
]
=
10
−
14
0.648
=
?
?
p
H
=
−
log
10
[
H
+
]
=
−
log
10
(
0.648
)
=
?
?
Alternatively, we know further that
p
H
+
p
O
H
=
14
. Once you have
p
H
,
p
O
H
is easy to find. Take the antilogarithm of this to get
[
O
H
−
]
.
Answer link
<span>A physical change basically involves a change in physical properties. Some examples of physical properties include: texture, shape, size, color, volume, mass, weight, etc.
The water melting has changed the shape and therefore it's physical properties, but the chemical nature of the water has not been altered.
So that's why it's a physical change, and not a chemical change.</span>
We can use a variety of formulas to determine our answers here.
Our formula for pOH is -log(mol), and we can plug it in as -log(0.010). Take note that OH- is a base, not an acid.
So, the pOH of OH- is 2.
To find pH we can set up this simple equation:
pH + pOH = 14
All we need to do is subtract 2 from 14, therefore the pH is 12.
This makes sense since acids range in the pH of 1-6, and we are dealing with a base. Hope I could help!
