Question

Part A: A hydrochloric acid solution has a pH of 2.8. Calculate the concentration of hydronium and hydroxide ions in the solution.

Part B: A sodium hydroxide solution has a concentration of 7.1 x 10^3. Calculate the pH of the solution.

Part C: The hydrochloric acid and sodium hydroxide react together in neutralization reaction. Write the balanced chemical equation for the reaction. Label the acid, base, and salt.

Answer 1

$pH= -log [H3O^+]$

$2.8= [H3O^+]$

$-2.8= log[H3O^+]$

$10^{-2.8} = [H3O^+]$

0.001 = [H3O+]

$1.58×10^{-3}$

$POH = 14-2.8=11.2$

pOH = - log [molarity of OH-] = - log [ molarity of NaOH] , assuming full dissociation.

Thus, pOH = - log ( $7.1×10^{-3}$ ) = - (-2.15) = 2.25.

Now, for a solution , pH + pOH = 14

=> pH + 2.25 =14

=> pH = 11.75

HCl(aq) + NaOH(aq ) → NaCl (aq)+ H2O(l)