In a 1.2 M solution of KOH, a strong base, [H3O+] = _____, and [OH−] = _____.

Question

BlackTom AI · Accepted Answer

Question restatement: In a 1.2 M solution of KOH, a strong base, [H3O+] = _____, and [OH−] = _____.

Option-by-option analysis:
Option 1: 8.3 × 10−15 M; 1.2 M. This aligns with the chemistry of a strong base parent solution. For a strong base like KOH, it dissociates completely, so [OH−] equals the concentration of KOH, i.e., 1.2 M. The corresponding hydronium ion concentration is found from Kw = [H3O+][OH−] ≈ 1.0 × 10−14. Therefore [H3O+] = Kw / [OH−] = (1.0 × 10−14) / (1.2) ≈ 8.3 × 10−15 M. So this option matches both the expected [OH−] and the calculated [H3O+].
Option 2: 8.3 × 10−15 M; 1.0 × 10−14 M. Here, [H3O+] is computed correctly from Kw and the listed [OH−], but the stated [OH−] value (1.0 × 10−14 M) is far too small for a full dissociation of 1.2 M KOH; a strong base at 1.2 M would yield a much larger [OH−], specifically 1.2 M, not a fraction of a mole per liter. This reflects a misunderstanding of strong-base dissociation and ionic strength in solution. 
Option 3: 1.2 M; 1.2 M. This would imply [H3O+] equals [OH−], which would give Kw = [H3O+][OH−] = (1.2)(1.2) = 1.44,000, which is not physically meaningful for aqueous solution at standard conditions; moreover, for a basic solution with a strong base, [H3O+] should be much smaller than 1, and certainly not equal to [OH−] when the base concentration is 1.2 M. This option mixes up the fundamental relationship between [H3O+] and [OH−] and misapplies Kw. 
Option 4: 1.2 M; 8.3 × 10−15 M. This reverses the expected roles: [OH−] should be the large value around 1.2 M for a 1.2 M KOH solution, while [H3O+] should be the very small Kw-derived value near 10−14 divided by 1.2, i.e., ~8 × 10−15 M; placing 1.2 M as [H3O+] and the tiny number as [OH−] contradicts the chemistry of a strong base in water and would imply an improbable proton-rich basic solution. This option flips the correct magnitudes and is inconsistent with the established expression Kw = [H3O+][OH−].

Synthesis of the underlying concept: In a solution of a strong base like KOH, dissociation is complete, so [OH−] equals the base concentration (1.2 M). The hydronium concentration is determined by Kw, yielding a very small value around 8 × 10−15 M. The incorrect options fail because they either misstate the extent of dissociation, miscalculate Kw, or invert the expected concentrations, reflecting common conceptual mistakes about acid-base equilibrium.

CHM-1020-LD01.2025SU Quiz 4-Acids and bases

In a 1.2 M solution of KOH, a strong base, [H3O+] = _, and [OH−] = _.

查看解析

登录即可查看完整答案

类似问题

if a solution has a proton concentration of 10-11 M, what is the hydroxide ion concentration? Please choose the correct answer from the following choices, and then select the submit answer button.

What is true about an acidic solution at 25°C?

What is the pH of a solution when [OH−] = 3.8 × 10−5. Is this solution acidic or basic?

Match the correct response When the pH of a solution rises what happens to the followings 1: [H3O+] [H3O+] 2: pOH 3: [OH-] [OH-] 4: [H3O+]x [OH-] [H3O+] x [OH-]