The answer is A-Gravity. Why? This is because B and C are examples of chemical weathering and not mechanical. Although choice D may seem viable lava intrusion is not a direct cause of mechanical weathering although lava pushing upward may help in aiding mechanical weathering it would not be considered a big enough cause, thus gravity is the correct answer.
Answer:
2.3 x 10-23 g.
Explanation:
The mass of a single atom is the mass number, 14, is the mass in grams of one mole of carbon.
One mole of Nitrogen atom is 6.022 x 1023 atoms (Avogadro's number). This can then used to convert a nitogen atom to grams by the ratio:
mass of 1 atom / 1 atom = mass of a mole of atoms / 6.022 x 10^23 atoms.
mass of 1 atom = mass of a mole of atoms / 6.022 x 1023
mass of 1 N atom = 14 / 6.022 x 10^23 N atoms
mass of 1 N atom = 2.325 x 10^-23 g
The mass of a single Nitrogen atom is 2.325 x 10-23 g.
(a)
pH = 4.77
; (b)
[
H
3
O
+
]
=
1.00
×
10
-4
l
mol/dm
3
; (c)
[
A
-
]
=
0.16 mol⋅dm
-3
Explanation:
(a) pH of aspirin solution
Let's write the chemical equation as
m
m
m
m
m
m
m
m
l
HA
m
+
m
H
2
O
⇌
H
3
O
+
m
+
m
l
A
-
I/mol⋅dm
-3
:
m
m
0.05
m
m
m
m
m
m
m
m
l
0
m
m
m
m
m
l
l
0
C/mol⋅dm
-3
:
m
m
l
-
x
m
m
m
m
m
m
m
m
+
x
m
l
m
m
m
l
+
x
E/mol⋅dm
-3
:
m
0.05 -
l
x
m
m
m
m
m
m
m
l
x
m
m
x
m
m
m
x
K
a
=
[
H
3
O
+
]
[
A
-
]
[
HA
]
=
x
2
0.05 -
l
x
=
3.27
×
10
-4
Check for negligibility
0.05
3.27
×
10
-4
=
153
<
400
∴
x
is not less than 5 % of the initial concentration of
[
HA
]
.
We cannot ignore it in comparison with 0.05, so we must solve a quadratic.
Then
x
2
0.05
−
x
=
3.27
×
10
-4
x
2
=
3.27
×
10
-4
(
0.05
−
x
)
=
1.635
×
10
-5
−
3.27
×
10
-4
x
x
2
+
3.27
×
10
-4
x
−
1.635
×
10
-5
=
0
x
=
1.68
×
10
-5
[
H
3
O
+
]
=
x
l
mol/L
=
1.68
×
10
-5
l
mol/L
pH
=
-log
[
H
3
O
+
]
=
-log
(
1.68
×
10
-5
)
=
4.77
(b)
[
H
3
O
+
]
at pH 4
[
H
3
O
+
]
=
10
-pH
l
mol/L
=
1.00
×
10
-4
l
mol/L
(c) Concentration of
A
-
in the buffer
We can now use the Henderson-Hasselbalch equation to calculate the
[
A
-
]
.
pH
=
p
K
a
+
log
(
[
A
-
]
[
HA
]
)
4.00
=
−
log
(
3.27
×
10
-4
)
+
log
(
[
A
-
]
0.05
)
=
3.49
+
log
(
[
A
-
]
0.05
)
log
(
[
A
-
]
0.05
)
=
4.00 - 3.49
=
0.51
[
A
-
]
0.05
=
10
0.51
=
3.24
[
A
-
]
=
0.05
×
3.24
=
0.16
The concentration of
A
-
in the buffer is 0.16 mol/L.
hope this helps :)
Answer:
0.51
Explanation:
Given the Nernst equation;
E= E° - 0.0592/n logQ
E= 355 mV or 0.355 V
E° = 0.34 - 0= 0.34 V
n= 2(two electrons were transferred in the process)
Equation of the reaction;
H2(g) + Cu^2+(aq) -----> 2H^+(aq) + Cu(s)
Substituting values;
0.355 = 0.34 - 0.0592/2 log([H^+]/1)
0.355 - 0.34 = - 0.0296 log [H^+]
0.015/-0.0296 = log [H^+]
Antilog (-0.5068) = [H^+]
[H^+] = 0.311 M
pH = -log[H^+]
pH= - log(0.311 M)
pH = 0.51
