Question

15. You mix a solution of a strong acid with a pH of 4 and an equal volume of a strong acid solution with a pH of 6. Is the final pH less than 4, between 4 and 5, 5, between 5 and 6, or greater than 6? Explain.

Answer 1

p^H = 4 p^H = -l middot j [H^+] = 4 [H^+] = 10^-4 m for other solution p^H = 6 rightwardsdoublearrow p^H = -l middot j [H^+] = 6 rightwardsdoublearrow [H^+] = 10^-6 m we mix equal volumes of solutions. Let final volume is v + v = 2v, and conc^n of [H^+] = m rightwardsdoublearrow m v = m_1 v_1 + m_2 v_2 rightwardsdoublearrow m times 2v = 10^-4 times v + 10^-6 times v rightwardsdoublearrow m = 5.05 times 10^-5 rightwardsdoublearrow [H^+] = 53.05 times 10^-5 rightwardsdoublearrow p^H = -log [H^+] = -log (5.05 times 10^-5) rightwardsdoublearrow p^H = 4.3 rightwardsdoublearrow 4 < p^H < 5 rightwardsdoublearrow between 4 & s