Chapter 14: Q113 E (page 837)
Draw a curve for a series of solutions of HF. Plot \({\left[ {{H_3}{O^ + }} \right]_{total }}\) on the vertical axis and the total concentration of HF (the sum of the concentrations of both the ionized and nonionized HF molecules) on the horizontal axis. Let the total concentration of HF vary from \(1 \times 1{0^{ - 10}}M\) to\(1 \times 1{0^{ - 2}}M\) .
Short Answer
\(\begin{array}{*{20}{r}}{(HF) = 1 \times 1{0^{ - 10}}M/\left( {{H_3}{O^ + }} \right) = 1.001 \times 1{0^{ - 7}}M}\\{(HF) = 1 \times 1{0^{ - 9}}M/\left( {{H_3}{O^ + }} \right) = 1.01 \times 1{0^{ - 7}}M}\\{(HF) = 1 \times 1{0^{ - 8}}M/\left( {{H_3}{O^ + }} \right) = 1.1 \times 1{0^{ - 7}}M}\\{(HF) = 1 \times 1{0^{ - 7}}M/\left( {{H_3}{O^ + }} \right) = 2 \times 1{0^{ - 7}}M}\\{(HF) = 1 \times 1{0^{ - 6}}M/\left( {{H_3}{O^ + }} \right) = 1.1 \times 1{0^{ - 6}}M}\\{(HF) = 1 \times 1{0^{ - 5}}M/\left( {{H_3}{O^ + }} \right) = 1.01 \times 1{0^{ - 5}}M}\\{(HF) = 1 \times 1{0^{ - 4}}M/\left( {{H_3}{O^ + }} \right) = 8.13 \times 1{0^{ - 5}}M}\\{(HF) = 1 \times 1{0^{ - 3}}M/\left( {{H_3}{O^ + }} \right) = 4.42 \times 1{0^{ - 4}}M}\\{(HF) = 1 \times 1{0^{ - 2}}M/\left( {{H_3}{O^ + }} \right) = 17.04 \times 1{0^{ - 4}}M}\end{array}\)
Step by step solution
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 10}}}}{\bf{M}}\)\(\)
The reaction
- \({K_a}\) of \(HF\) is \(3.5 \times 1{0^{ - 4}}\)
- Concentration of HF varies from\(1 \times 1{0^{ - 10}}M\)to\(1 \times 1{0^{ - 2}}M\)
Let us draw a curve for a series of solutions of \(HF\) (vertical axis \(\left[ {{H_3}{O^ + }} \right]\) and horizontal axis [HF] (ionized and nonionized) )
- Since the concentration of \({H_3}{O^ + }\) an ion in pure water is \(1 \times 1{0^{ - 7}},\) the initial concentration of \({H_3}{O^ + }\) in a given solution will be \(1 \times 1{0^{ - 7}}.\)
\([HF] = 1 \times 1{0^{ - 10}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 10}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium(M) | \(1.1{0^{ - 10}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 10}} - x}}\\3.5 \times 1{0^{ - 14}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 14}}\\x = 1 \times 1{0^{ - 10}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 10}} = 1.001 \times 1{0^{ - 7}}\end{array}\)
To find the concentration of HF varies in \[{\bf{1}} \times {\left( {{\bf{10}}} \right)^{ - {\bf{9}}}}\]
\([HF] = 1 \times 1{0^{ - 9}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 9}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 9}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 9}} - x}}\\3.5 \times 1{0^{ - 13}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 13}}\\x = 1 \times 1{0^{ - 9}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 9}} = 1.01 \times 1{0^{ - 7}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 8}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 8}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 8}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 8}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 8}} - x}}\\3.5 \times 1{0^{ - 12}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 12}}\\x = 1 \times 1{0^{ - 8}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 8}} = 1.1 \times 1{0^{ - 7}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 7}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 7}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 7}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 7}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 7}} - x}}\\3.5 \times 1{0^{ - 11}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 11}}\\x = 1 \times 1{0^{ - 7}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 7}} = 2 \times 1{0^{ - 7}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 6}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 6}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 6}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 6}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 6}} - x}}\\3.5 \times 1{0^{ - 10}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 10}}\\x = 1 \times 1{0^{ - 6}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 6}} = 1.1 \times 1{0^{ - 6}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 5}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 5}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 5}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 5}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[H\;F]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 5}} - x}}\\3.5 \times 1{0^{ - 9}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 9}}\\x = 1 \times 1{0^{ - 5}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 1 \times 1{0^{ - 5}} = 1.01 \times 1{0^{ - 5}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 4}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 4}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 4}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 4}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\[\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 4}} - x}}\\3.5 \times 1{0^{ - 8}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 8}}\\x = 8.12 \times 1{0^{ - 5}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 8.12 \times 1{0^{ - 5}} = 8.13 \times 1{0^{ - 5}}\end{array}\]
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 3}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 3}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 3}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 3}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 3}} - x}}\\3.5 \times 1{0^{ - 7}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 7}}\\x = 4.42 \times 1{0^{ - 4}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 4.42 \times 1{0^{ - 4}} = 4.42 \times 1{0^{ - 4}}\end{array}\)
To find the concentration of HF varies in \({\bf{1 \times 1}}{{\bf{0}}^{{\bf{ - 2}}}}{\bf{M}}\)
\([HF] = 1 \times 1{0^{ - 2}}M\)
\[HF(aq) \to \] | \({H_3}{O^ + }(aq)\) | \({F^ - }(aq)\) | |
Initial (M) | \(1.1{0^{ - 2}}\) | \(1.1{0^{ - 7}}\) | 0 |
Change (M) | -X | +X | +X |
Equilibrium (M) | \(1.1{0^{ - 2}} - X\) | \(1.1{0^{ - 7}} - X\) | X |
\(\begin{array}{l}{K_a} = \frac{{\left[ {{H_3}{O^ + }} \right] \times \left[ {{F^ - }} \right]}}{{[HF]}}\\3.5 \times 1{0^{ - 4}} = \frac{{\left( {1 \times 1{0^{ - 7}} + x} \right) \times x}}{{1 \times 1{0^{ - 2}} - x}}\\3.5 \times 1{0^{ - 6}} - 3.5 \times 1{0^{ - 4}}x = 1 \times 1{0^{ - 7}}x + {x^2}\\0 = {x^2} + 3.5 \times 1{0^{ - 4}}x - 3.5 \times 1{0^{ - 6}}\\x = 17.04 \times 1{0^{ - 4}}\\\left[ {{H_3}{O^ + }} \right] = 1 \times 1{0^{ - 7}} + 17.04 \times 1{0^{ - 4}} = 17.04 \times 1{0^{ - 4}}\end{array}\)
Step 10:
\(\begin{array}{l} A curve for a series of solutions of HF ( vertical axis \left[ {{H_3}{O^ + }} \right]and horizontal axs [HF] \\(ionized and nonionized)) \end{array}\)
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