1. What is the Kb for B-, if the Ka for the acid (HB) is 2.5 x 10-8?
2. What is the hydronium ion concentration of a 3.50 x 10-2 M solution of the monoprotic acid, HBrC6H4COO, for which Ka = 1.00 x 10-4?
3. What is the Ka value for HB, if a solution that is 0.25 M B- and 0.55 M HB produces a pH of 4.95?
4. Calculate the pH of a solution containing .225 moles of lactic acid (HC3H5O3) in water to produce one liter of solution. (Ka = 1.4 x 10-4)
(1) The relation between Kb , Ka & Kw is Kw = Ka x Kb
Kb = Kw / Ka
= (1.0x10-14) / (2.5x10-8)
= 4.0x10-7
Therefore Kb for B- 4.0x10-7
(2) Let a be the dissociation of the weak acid
HA <---> H + + A-
initial conc. c 0 0
change -ca +ca +ca
Equb. conc. c(1-a) ca ca
Dissociation constant , Ka = ca x ca / ( c(1-a)
= c a2 / (1-a)
In the case of weak acids a is very small so 1-a is taken as 1
So Ka = ca2
==> a = √ ( Ka / c )
Given Ka = 1.00x10-4
c = concentration = 3.50x10-2 M
Plug the values we get a = 0.0534
So [H+] = ca = 3.50x10-2 M x 0.0534 = 1.87x10-3 M
Therefore the [H+] = 1.87x10-3 M
(3) According to Henderson's equation, pH = pKa + log ([B-]/[HB])
pKa = pH - log ([B-]/[HB])
= 4.95 - log(0.25/0.55)
= 5.29
(4) Let a be the dissociation of the weak acid
HA <---> H + + A-
initial conc. c 0 0
change -ca +ca +ca
Equb. conc. c(1-a) ca ca
Dissociation constant , Ka = ca x ca / ( c(1-a)
= c a2 / (1-a)
In the case of weak acids a is very small so 1-a is taken as 1
So Ka = ca2
==> a = √ ( Ka / c )
Given Ka = 1.4x10-4
c = concentration = number of moles / volume in L
= 0.225 mol / 1.0 L
= 0.225 M
Plug the values we get a = 0.0249
[H+] = ca = 0.225 M x 0.0249 = 5.612x10-3 M
pH = - log[H+] = 2.25
Lactic acid, HC3H5O3 , is a weak acid in aqueous solution, Ka = 1.4 × 10−4 . Calculate Kb for the lactate ion, C3H5O –
A buffer solution is made such that the initial concentrations of lactic acid (HC3H5O3) and the lactate ion (C3H5O3-) are both 0.600 M. What is the resulting pH if 10.0 mL of 1.00 M HCL is added to 0.500 of the buffer solution? (ka of HC3H5O3= 1.4 x 10^-4)
10. (a) Determine the pH of 0.10 M lactic acid (HC3H5O3) (b) What is the pH of a buffer that is 0.12 M lactic acid and 0.10 M sodium lactate (NaC2H5O3)? For lactic acid. Ka - 1.4 x 104. (10) 11. Hydrazine, N2H4, is a weak base. Write the equation for the reaction of hydrazine with water and write the expression for Kb. (5) Na Hj
11a) 1.00 moles of lactic acid (HC3H5O3, Ka = 1.4 x 10-4) and 1.00 moles of sodium lactate (NaC3H5O3) are dissolved in water resulting in a solution with a final volume of 550 mL. What is the pH of the solution after the addition of 0.080 moles of HCI? a. 0.80 b. 1.8 C. 2.8 d. 3.8
12. Lactic acid (HC3H5O3) is present in sour milk It is a monoprotic acid. In a 0.100 M solution of lactic acid, the pH is 2.44 at 25°C. Calculate Ka and pKa for lactic acid at that temperature. (10)
Lactic acid is found in muscles after exercising and has a Ka = 1.4 x 10-4. A 350.0 mL solution contains 0.060 moles of lactic acid and 0.040 moles of sodium lactate. What is the pH of the solution after the addition of 0.015 moles of HNO3?
1. a)Calculate the pH of a 0.30M formic acid solution (Ka=1.8*10^-4)Weak monoprotic acid. b)Calculate the Ka for a 0.050M solution of HA (weak avid if the pH=4.65 c)What is the pH of the solution which results from mixing 50.0mL of 0.30M HF (aq) and 50.0mL of 0.30M NaOH (aq) at 25C? (Kb of F- =1.4*10^-11) I am having a hard time with these so as much detail as possible would be great, thank you for your time and your help.
(3 points) A 0.0730 M solution of a monoprotic acid is 1.07% ionized. What is the pH of the solution? Calculate the Ka of the acid. (2 points) The pH of a 0.025 M solution of a monoprotic acid is 3.21. What is the Ka value for the acid? (2 points) Determine the percent ionization of a 0.0028 M HA solution. (Ka of HA = 1.4 x 10-9) (4 points) Lysine is triprotic amino acid (separately loses three H’s in...
A monoprotic weak acid has a Ka of 1.44 x 10-4. What would be the pH if 1.03 moles of the acid is dissolved in 1 liter of water?
Problem 15.50 The equilibrium constant Kn for the neutralization of lactic acid (HC3H5O3) and urea (CH4N2O) is 2.1�10?4. Part A What is Kb for urea? Ka of lactic acid is 1.4�10?4. Express your answer using two significant figures. Kb =