Question

WILSPILUIS SUSITIU 41722 Tourse o 25 1650 TocontentId = Question Completion Status: QUESTION 15 Calculate the pH of 0.026 M HC104. a. 1.59 b. 12.41 c. None of these d. 0.026 Oe. 7.00 Caps Lock is on QUESTION 16 Calculate the pH of a 0.045 M HCl solution a. 1.23 b. none of these c.12.65 d. 1.35 e. 12.29

Answer 1

pH is a measure of concentration of hydrogen ions (H⁺) in a solution. Mathematically it is the negative logarithm of concentration of hydrogen ions, that is pH = -log [H⁺] .

Ques 15.

HClO_​​​4 will dissociate in solution as : HClO_​​​4 → H⁺ + ClO_{​​​​4} ^-

Thus 1 mole of HClO_​​​4 will produce 1 mole of H⁺ ions which means concentration of H⁺ ions produced by HClO_​​​4 is same as the concentration of HClO_​​​4 .

Given concentration of HClO_​​​4 = 0.026 M

Thus concentration of H⁺ ions is also 0.026 M , that is [H⁺] = 0.026M

Therefore pH = -log (0.026) = - (-1.585) = 1.585 = 1.59 ( by rounding off)

Thus option a is the correct answer.

Ques 16.

HCl dissociates in solution as : HCl → H⁺ + Cl^{​​​​​-}

Thus concentration of H⁺ ions produced by HCl is same as the concentration of HCl since 1 mole of HCl produces 1 mole of H⁺.

Given concentration of HCl = 0.045 M

So concentration of H⁺ ions in the solution is also 0.045 M , that is [H⁺] = 0.045 M

Thus pH = -log (0.045) = - (-1.346) = 1.346 = 1.35 (by rounding off)

Thus option d is the correct answer.