Chapter 16, Problem 144E

Interpretation Introduction

Interpretation:

The of the quinine (Q) should be determined.

Concept introduction:

     Molarity:

     The number of moles of solute per liter of solution is known as molarity of the solution. It symbolized by . Molarity of any solution is a ratio of moles of solutes per liter of solution. It expressed by the following formula:

$\text{Molarity (}M)=\frac{\text{moles of solutes}}{\text{liter of solution}}$

     The pH of any solution is defined as the negative logarithm of the hydrogen ion concentration.

$pH=-\log \left[H^{\text{+}}\right]$

     The dissociation reaction of the HA weak acid, with H⁺(aq) as product is as follows:

$HA\left(aq\right)\to H^{+}\left(aq\right)+A^{-}\left(aq\right)$

     The expression for ionization constant (K_a)is as follows:

$K_a=\frac{\left[A_{}^{-}\right]\left[H^{+}\right]}{\left[HA\right]}$

     The auto-ionization of water can be written as follows:

$H_{2}O\left(l\right)\to H^{+}\left(aq\right)+O{H}^{-}\left(aq\right)$

     Therefore;

$K_w=\left[H_3{O}^{+}\right]\left[O{H}^{-}\right]=\left[H^{+}\right]\left[O{H}^{-}\right]=1.0\times {10}^{-14}$

Given:

The pH of the chloride salt of protonated quinine QH⁺ is 4.58, and number of mole of QH⁺ is 0.23 in 1.00 L solution.