Please help me with this homework
1 answer:
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Explanation:
According to the Henderson-Hasselbalch equation, the relation between pH and is as follows.
pH =
where, pH = 7.4 and = 7.21
As here, we can use the nearest to the desired pH.
So, 7.4 = 7.21 +
0.19 =
= 1.55
1 mM phosphate buffer means +
= 1 mM
Therefore, the two equations will be as follows.
= 1.55 ............. (1)
+
= 1 mM ........... (2)
Now, putting the value of from equation (1) into equation (2) as follows.
1.55 = 1 mM
2.55 = 1 mM
= 0.392 mM
Putting the value of in equation (1) we get the following.
0.392 mM + = 1 mM
= (1 - 0.392) mM
= 0.608 mM
Thus, we can conclude that concentration of the acid must be 0.608 mM.
A electrochemical reaction is said to be spontaneous, if 
Answer 1:
Consider reaction: <span>Ni^2+ (aq) + S^2- (aq) ----> + Ni (s) + S (s)
The cell representation of above reaction is given by;
</span>
Hence,
we know that,
and
Therefore,
= - 0.25 - (-0.47) = 0.22 v
Since, is positive, hence cell reaction is spontaneous
.....................................................................................................................
Answer 2:
Consider reaction: <span>Pb^2+ (aq) +H2 (g) ----> Pb (s) +2H^+ (aq)
</span>
The cell representation of above reaction is given by;
Hence,
we know that,
and
Therefore, = - 0.126 - 0 = -0.126 v
Since, is negative, hence cell reaction is non-spontaneous.
....................................................................................................................
Answer 3:
Consider reaction: <span>2Ag^+ (aq) + Cr(s) ---> 2 Ag (s) +Cr^2+ (aq)
</span>
The cell representation of above reaction is given by;
Hence,
we know that,
and
Therefore, = - 0.22 - (-0.913) = 0.693 v
Since, is positive, hence cell reaction is spontaneous
Answer 1:
Consider reaction: <span>Ni^2+ (aq) + S^2- (aq) ----> + Ni (s) + S (s)
The cell representation of above reaction is given by;
</span>
Hence,
we know that,
and
Therefore,
Since,
.....................................................................................................................
Answer 2:
Consider reaction: <span>Pb^2+ (aq) +H2 (g) ----> Pb (s) +2H^+ (aq)
</span>
The cell representation of above reaction is given by;
Hence,
we know that,
and
Therefore,
Since,
....................................................................................................................
Answer 3:
Consider reaction: <span>2Ag^+ (aq) + Cr(s) ---> 2 Ag (s) +Cr^2+ (aq)
</span>
The cell representation of above reaction is given by;
Hence,
we know that,
and
Therefore,
Since,
Answer : The correct option is, (D) 89.39 KJ/mole
Explanation :
First we have to calculate the moles of HCl and NaOH.
The balanced chemical reaction will be,
From the balanced reaction we conclude that,
As, 1 mole of HCl neutralizes by 1 mole of NaOH
So, 0.3562 mole of HCl neutralizes by 0.3562 mole of NaOH
Thus, the number of neutralized moles = 0.3562 mole
Now we have to calculate the mass of water.
As we know that the density of water is 1 g/ml. So, the mass of water will be:
The volume of water =
Now we have to calculate the heat absorbed during the reaction.
where,
q = heat absorbed = ?
= specific heat of water =
m = mass of water = 274 g
= final temperature of water = 325.8 K
= initial temperature of metal = 298 K
Now put all the given values in the above formula, we get:
Thus, the heat released during the neutralization = -31.84 KJ
Now we have to calculate the enthalpy of neutralization.
where,
= enthalpy of neutralization = ?
q = heat released = -31.84 KJ
n = number of moles used in neutralization = 0.3562 mole
The negative sign indicate the heat released during the reaction.
Therefore, the enthalpy of neutralization is, 89.39 KJ/mole