I have the answer I just want to know the steps and the reasons why Chapter 14 Q
ID: 521128 • Letter: I
Question
I have the answer I just want to know the steps and the reasons why
Chapter 14 Question 81 Multiple Choice Part A Calculate the concentration of bicarbonate ion, HCO3 in a 0.010 M H2CO3 solution that has the stepwise dissociation constants Kal 4.3 x 10 and Ka 5.6 x 10 11 ANSWER: C 5.6 x 10 11 M 6.6 x 10 M 4.3 x 10 M 4.3 x 10 M Chapter 14 Question 96 Multiple Choice Part A Which one of the following salts, when dissolved in water, produces the solution with the highest pH? ANSWER: C NaHSO Mgo C CH3NH3I C LiClOExplanation / Answer
81)
H2CO3 <==> H+ + HCO3- Ka1=4.3x10^-7
HCO3- <==> H+ + CO32- Ka2=5.6x10^-11
Let X be the concentration [HCO3 -], Y be [CO32-], and Z be [OH-]
Then,
H2CO3 <==> H+ + HCO3-
Initially 0.01 10^-7 0.00
at balance:(0.01-X-Y) (X+2Y+Z) X
HCO3 - <==> H+ + CO32-
Initially 0.00 10^-7 0.00
Balance: X (X+2Y+Z) Y
H2O <==> H++ OH-
Initially 10^-7 10^-7
Balance (X+2Y+Z) Z
Ka1 = [H2][HCO3-]/[H2CO3] = X(X+2Y+Z)/(0.01-X-Y) (1)
Ka2 = [H+][CO32-]/[HCO3-] = Y(X+2Y+Z)/X (2)
Kw = [H+][OH-] = Z(X+2Y+Z) (3)
Assume that 0.01 >X>Y and X>Z. thus (1) is simplified to be:
Ka1 = X^2/0.01
X^2 = 4.3x10^-7 x 0.01M
X = 6.557 x 10^-5 M
X = [HCO3-] = 6.6 x 10^-5M (2significant figure)
2) 6.6 x 10^-5M is correct.
96)
NaHSO4 is a very weak acid
NaHSO4 (aq) -----> Na+ and HSO4-
HSO4- can give off some protons, so acts as a weak acid.
CH3NH3I is a weak acid.
LiClO4. Is neutral
MgO + H2O -----> Mg(OH)2
Mg(OH)2 is base, so it produces solution with high PH.
2) MgO is correct
The strength of acids in decreasing order HClO4> HClO3 > HClO3 > HClO
HClO4 HClO3 and HClO2 will ionize in greater extent compared to HClO. ClO^- ion will be the strongest base since its conjugate acid (HClO) is the weakest. Most of the hypochlorite ions will combine H+ from water leaving a high concentration of OH- ion.
1) CLO- is correct.