Question

pH of a Strong Acid and a Strong Base 11 of 16 > II Review Constants Periodic Table pH is a logarithmic scale used to indicate the hydrogen ion concentration, H'], of a solution: pH = -log[H] The temperature for each solution is carried out at approximately 297 K where Ky = 1.00 x 10-14 Part A Due to the autoionization of water, in any aqueous solution, the hydrogen ion concentration and the hydroxide ion concentration, OH-], are related to each other by the Ky of water: Kw = [H'[OH]=1.00 x 10-14 0.60 g of hydrogen chloride (HCl) is dissolved in water to make 4.0 L of solution. What is the pH of the resulting hydrochloric acid solution? Express the pH numerically to two decimal places. View Available Hint(s) where 1.00 x 10-14 is the value at approximately 297 K. Based on this relation, the pH and pOH are also related to each other as 14.00 =pH + pOH 10 ALQ R O ? pH = Submit Part B 0.50 g of sodium hydroxide (NaOH) pellets are dissolved in water to make 8.0 L of solution. What is the pH of this solution? Express the pH numerically to two decimal places. View Available Hint(s) VO AQ R O a ? pH =

Answer 1

Part-A

Mass of HCI 0.60 g Molar Mass of HCI Moles of HCI 36.46 g/mol Mass of HCl / Molar mass of HCI 0.60 g 36.46 g/mol = 0.0165 mol Volume of solution 4.00 L Molarity of solution Moles of HCl + Volume of solvent in L 0.0165 mol = 4.00 L = 0.0041 M

HCl is strong Acid [HCl] = [H+] = 0.0041 M

M Given [H+ we know pH = -log [H+] So pH of the given solution = = = 0.0041 -log [ 2.39 0.0041 ]

Part:B:

Mass of NaOH 0.50 g Molar Mass of NaOH Moles of NaOH 40.00 g/mol Mass of NaOH / Molar mass of NaOH 0.50 g 40.00 g/mol = 0.0125 mol Volume of solution 8.00 L Molarity of solution Moles of NaOH + Volume of solvent in L 0.0125 mol = 8.00 L = 0.0016 M

for strong Base [NaOH] = [OH] = 0.0016 M

Given [OH-] we know pOH = -log [OH-] So pOH of the given solution = = = 0.0016 -log[ 2.80 1.60E-03 ] We know pH + pOH pH = 14 - pOH so pH of given solution = = 14.00 14 - 11.2 2.80