Question

Question 25 An aqueous solution at has a concentration of . Calculate the concentration. Be sure your answer has the correct number of significant digits.

Answer 1

The given question is lacking some details, the complete question is following

Question:

An aqueous solution at 25 °C has a OH⁻ concentration of 2.5 x 10⁻⁴ M . Calculate the H₃O⁺ concentration. Be sure your answer has the correct number of significant digits

Answer:

Concentration of H₃O⁺ is:

$[H_{3}O^{+}]=4.0X10^{-9} M$

Explanation:

In aqueous solutions the product of the concentration of hydronium ions H₃O⁺ and hydroxide ions OH⁻ is 1.0 x 10⁻¹⁴. This value is the dissociation or ionization constant of water at 25 °C. Its formula is given as:

$Kw = [H_{3} O^{+}][OH^{-} ]$

$1.0 X 10^{-14}= [H_{3}O^{+}](2.5 X 10^{-4})$

$[H_{3}O^{+}]= \frac{1.0X10^{-14}}{2.5 X 10^{-4}}$

$[H_{3}O^{+}]=4.0X10^{-9} M$

P.S: As the smallest number of significant figure in the ratio was two, so the answer contains two significant figures.