question archive Calculate the percent ionization (the approximation percentage) for the reaction in equation #4 if the initial concentration of HI is 0
Calculate the percent ionization (the approximation percentage) for the reaction in equation #4 if the initial concentration of HI is 0
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Calculate the percent ionization (the approximation percentage) for the reaction in equation #4 if the initial concentration of HI is 0.046 and the concentration at equilibrium is 2.0 times 10^-3 M. What is the p0H of a 0.40 M ammonia solution? K_b = 1.3 times 10^-5 NH_3 + H_20 NH_4^+ + OH^- What is the value of p0H in the above equation? Is the approximation valid for
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7)
Ci = 0.046 M
Cf = 2.0*10^-3 M = 0.002 M
amount ionized,
x = Cf - Ci
= 0.046 - 0.002
=0.044 M
% ionisation = x*100/Ci
= 0.044*100/0.046
= 95.7 %
Answer: 95.7 %
8)
NH3 + H2O -----> NH4+ + OH-
0.40 0 0
0.40-x. x x
Kb = [NH4+][OH-]/[NH3]
Kb = x*x/(c-x)
since kb is small, x will be small and it can be ignored as compared to c
So, above expression becomes
Kb = x*x/(c)
so, x = sqrt (Kb*c)
x = sqrt ((1.3E-5)*0.40) = 2.28E-3
So,
[OH-] = 2.28E-3 M
pOH = -log [OH-] = -log (2.2804E-3) = 2.64
Answer: 2.64
