A. Strong Base
1.) What is the concentration of a solution of KOH for which the pH is 11.89?
2.) What is the pH of a 0.011M solution of Ca(OH)2?
B. Weak Acid
1.) The pH of a 0.060M weak monoprotic acid HA is 3.44. Calculate the Ka of the acid.
2.) The pH of 0.100M solution of weak monoprotic acid HA is 2.85. What is the Ka of the acid?
C. SALT HYDROLYSIS
1.) Calculate the pH of a 0.24M sodium formate (HCOONa) solution. Kb=5.9x10^-11.
2.) Calculate the pH of 0.25M pyridium chloride (C5H5NHCl)solution. Ka=5.9x10^6.
D. COMMON ION EFFECT
1.) What is the pH of a solution that is 0.30M in HCOOH and 0.52M in HCOOK.
Ka of HCOOH=1.7x10^-4.
2.) Calculate the pH of a buffer system containing 1.0M CH3COOH and 1.0M CH3COONa. Ka of CH3COOH=1.8x10^-5.
Please help.... i do not know what to do....
Please do not put long lists of questions as it is unlikely that they will all get answered. Have you had go at answering any of them?
1)
if pH =11.89 then
pOH=14-11.89=2.11
(this assumes that Kw=10^-14, i.e. that the solution is at ca 25C)
[OH-]=10^-pOH
2)
if concentration is 0.011M then the OH- concentration is twice this as each mole of CaOH2 yields two moles of OH-
so[OH-]=0.022M
pOH=-log([OH-]/mole litre^-1)
then pH=14-pOH
(same assumption as above)
B
1)
HA<-> H+ + A-
at start
0.060M
at equilibrium
0.06-x x x
if pH=3.44 then x=[H+]=10^-3.44
Ka=[H+][A-]/[HA]
so
Ka=x^2/(0.06-x)
find Ka
i need answer
Sure! I can help you with these questions step by step. Let's go through each one and explain how to find the answer.
A. Strong Base:
1.) To find the concentration of a solution of KOH for which the pH is 11.89, we can use the formula for calculating pH: pH = -log[H+].
In this case, we need to find the concentration of hydroxide ions (OH-) since KOH is a strong base. OH- is the conjugate base of water, so we know that [OH-] = [H+]. Therefore, we can convert the given pH to [OH-] concentration by taking the antilog of the negative pH value: [OH-] = 10^(-pH).
2.) Similarly, to find the pH of a 0.011M solution of Ca(OH)2, we need to find the concentration of hydroxide ions. Since Ca(OH)2 is a strong base, it completely dissociates in water to form two OH- ions. So, the concentration of [OH-] in this case would be twice the concentration of Ca(OH)2.
B. Weak Acid:
1.) To calculate the Ka of a weak monoprotic acid HA, we can use the formula: Ka = [H+][A-] / [HA], where [H+] is the concentration of hydronium ions, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the acid. Given the pH of the solution (pH = -log[H+]), we can calculate [H+].
2.) Similar to the first question, we can calculate the Ka of the weak monoprotic acid HA using the given pH value.
C. Salt Hydrolysis:
1.) For salt hydrolysis, we need to consider the hydrolysis of the salt and the reaction between the resulting ions with water. In this case, we have sodium formate (HCOONa). The key equation is: HCOO- + H2O ⇌ HCOOH + OH-. To calculate the pH, we need to determine the concentration of hydroxide ions ([OH-]) in the solution.
2.) Similarly, we can calculate the pH of the solution containing pyridium chloride (C5H5NHCl) by considering the hydrolysis of the salt and the reaction between the resulting ions with water.
D. Common Ion Effect:
1.) In the case of a solution containing both HCOOH and HCOOK, we need to consider the common ion effect. The common ion effect occurs when a weak acid (HCOOH) and its conjugate base (HCOO-) are present in the same solution. We need to calculate the equilibrium concentration of HCOOH and HCOO- and then use the Henderson-Hasselbalch equation to find the pH.
2.) Similarly, for a buffer system containing CH3COOH and CH3COONa, we need to consider the common ion effect and use the Henderson-Hasselbalch equation to calculate the pH.
By following these steps and using the appropriate equations, you should be able to solve each question. Good luck!