Respuesta :
Answer:
Part A: 10.7.
Part B: 2) the solution is basic.
Part C: 5.9.
Part D: 1) the solution is acidic.
Part E: 8.1.
Part F: 2) the solution is basic.
Explanation:
Part A [OH−]= 4.5×10−4 M . Express your answer using two significant figures.
∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.
[OH⁻] = 4.5×10⁻⁴ M.
∴ [H₃O⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(4.5×10⁻⁴ M) = 2.22 × 10⁻¹¹ M.
∵ pH = - log[H₃O⁺]
∴ pH = - log(2.22 × 10⁻¹¹) = 10.65 ≅ 10.7.
Part B 1) the solution is acidic 2) the solution is basic 3) the solution is neutral
The solution is basic, because the pH is higher than 7.
Part C [OH⁻]= 7.7×10⁻⁹ M . Express your answer using two significant figures.
∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.
[OH⁻] = 7.7×10⁻⁹ M.
∴ [H₃O⁺] = 10⁻¹⁴/[OH⁻] = 10⁻¹⁴/(7.7×10⁻⁹ M) = 1.29 × 10⁻⁶ M.
∵ pH = - log[H₃O⁺]
∴ pH = - log(1.29 × 10⁻⁶) = 5.88 ≅ 5.9.
Part D 1) the solution is acidic 2) the solution is basic 3) the solution is neutral
The solution is acidic, because the pH is lower than 7.
Part E A solution in which [OH−] is 140 times greater than [H+]. Express your answer using two significant figures.
∵ [H₃O⁺][OH⁻] = 10⁻¹⁴.
∵ [OH⁻] = 140[H₃O⁺]
∴ [H₃O⁺](140[H₃O⁺]) = 10⁻¹⁴.
∴ 140 [H₃O⁺]² = 10⁻¹⁴.
[H₃O⁺]² = 10⁻¹⁴/ 140 = 7.14 x 10⁻¹⁷.
∴ [H₃O⁺] = √(7.14 x 10⁻¹⁷) = 8.45 x 10⁻⁹ M.
∵ pH = - log[H₃O⁺]
∴ pH = - log(8.45 x 10⁻⁹) = 8.07 ≅ 8.1.
Part F 1) the solution is acidic 2) the solution is basic 3) the solution is neutral
The solution is basic, because the pH is higher than 7.
The hydrogen ion concentration for the first solution is 10.7, for the second 5.9 and the third 8.1. the solutions are basic, acidic and basic in order.
What is pH?
pH is the measure of the hydrogen ion concentration in the solutions that depicts the acidic and the basic nature of the solution.
We know, [tex]\rm [H_{3}O^{+}][OH^{-}] = 10^{-14}[/tex]
Given, [tex]\rm [OH^{-}]= 4.5 \times 10^{-4}\;\rm M[/tex]
Substituting values in the equation:
[tex]\begin{aligned}\rm [H_{3}O^{+}] &= \dfrac{10^{-4}}{\rm [OH^{-}]}\\\\&= \dfrac{10^{-4}}{4.5 \times 10^{-4}\;\rm M}\\\\&=2.22 \times 10^{-11} \;\rm M\end{aligned}[/tex]
Substituting concentration in the pH formula as:
[tex]\begin{aligned} \rm pH &= \rm - log \rm [H_{3}O^{+}]\\\\&= \rm - log(2.22 \times 10^{-11}) \\\\&= 10.7 \end{aligned}[/tex]
Hence, the solution is basic.
Given, [tex]\rm [OH^{-}]= 7.7 \times 10^{-9}\;\rm M[/tex]
Substituting values in the equation:
[tex]\begin{aligned}\rm [H_{3}O^{+}] &= \dfrac{10^{-4}}{\rm [OH^{-}]}\\\\&= \dfrac{10^{-4}}{7.7 \times 10^{-9}\;\rm M}\\\\&=1.29 \times 10^{-6} \;\rm M\end{aligned}[/tex]
Substituting concentration in the pH formula as:
[tex]\begin{aligned} \rm pH &= \rm - log \rm [H_{3}O^{+}]\\\\&=\rm - log(1.29 \times 10^{-6}) \\\\&= 5.9\end{aligned}[/tex]
Hence, the solution is acidic.
Given, the concentration of [tex]\rm [OH^{-}][/tex] is 140 times greater than [tex]\rm [H^{+}][/tex]
Substituting values in the equation:
[tex]\begin{aligned}\rm [H_{3}O^{+}][OH^{-}] &= 10^{-14}\\\\\rm [H_{3}O^{+}](140[H_{3}O^{+}]) &= 10^{-14}\\\\&= 8.45 \times 10^{-9}\;\rm M\end{aligned}[/tex]
Substituting concentration in the pH formula as:
[tex]\begin{aligned} \rm pH &= \rm - log \rm [H_{3}O^{+}]\\\\&= \rm - log(8.45 \times 10^{-9}) \\\\&= 8.1\end{aligned}[/tex]
Hence, the solution is basic.
Therefore, the pH below 7 is acidic and above 7 is basic.
Learn more about pH here:
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