What is the ph of a solution (500 ml, 3.40 mm hoac) in which 50 ml of 1.00 m hcl is added? what percentage of the hoac is dissociated?

a) pH = 1.0414

b) ∝ = 0.156 %

Explanation:

∴ n HCL = (0.05L)*( 1 mol/L) = 0.05 mol

       HCl → H3O+  +  Cl-

ni     0.05     -              -

nf      -         0.05       0.05

weak acid:

∴ mol CH3COOH = (0.500L)*(3.40 E-3 mol/L ) = 1.7 E-3 mol

    CH3COOH ↔ CH3COO- +   H3O+

ni     1.7 E-3                 -                0.05

nf    1.7 E-3 - X            X             0.05 + X ≅ 0.05

∴ Ka = 1.75 E- 5 = ([ H3O+]*[CH3COO-])/[CH3COOH]

by lechatelier the reaction shifts to the left, then the moles of H3O+ in the weak acid is practically equal to 0.05 moles of the strong acid.

⇒  [H3O+] = 0.05 mol / 0.55 L = 0.0909 M

⇒ pH = - Log ( 0.0909 )

⇒ pH = 1.0414

replacing en Ka:

⇒ 1.75 E-5 = ((0.05+X)/0.55)*(X/0.55)) / ((1.7 E-3-X)/0.55)

⇒ 0.55X² + 0.3025X - 8.99 E-9 = 0

⇒ X = 4.8424 E-6 M

⇒ [H3O+] = 0.05mol/0.55L + 4.8424 E-6 = 0.0909 M

the assumption has been demonstrated

∴ percentage of tha CH3COOH is dissociated (∝):

⇒ ∝ = ( [CH3COO-] / ([CH3COO-] + [CH3COOH]) ) * 100

∴ [CH3COO-] = X = 4.824 E-6 M

∴ [CH3COOH] = 1.7 E-3 mol/0.55 L - 4.824 E-6 = 3.086 E-3 M

⇒ ∝ = ((4.824 E-6) / (3.086 E-3 + 4.824 E-6 )) * 100

⇒ ∝ = 0.156 %

the answer is learned

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.