What is the hydroxide-ion concentration in a solution formed by combining 200.mL of 0.15 M HCl with 300.mL of 0.090 M NaOH at 25°C? HCl(aq)+ NaOH(aq)→ NaCl(aq)+ H₂O(l) A) 1.7 × 10^-13 M B) 0.090 M C) 1.7 × 10^-12 M D) 0.054 M E) 1.0 × 10^-7 M

Question

Quizplus · Accepted Answer

We need to use the balanced chemical equation to determine the amount of hydroxide ions produced from the reaction. From the equation, we see that the stoichiometry of the reaction is 1:1 between HCl and NaOH, so they will completely react with each other.

First, let's determine the amount of moles of HCl and NaOH used:

moles of HCl = (0.15 M) x (0.200 L) = 0.030 mol
moles of NaOH = (0.090 M) x (0.300 L) = 0.027 mol

Since HCl and NaOH react in a 1:1 ratio, the amount of HCl used is equal to the amount of NaOH used. Therefore, all of the HCl is neutralized by the NaOH, leaving only NaCl and water in solution.

Now, let's use the amount of moles of NaOH to calculate the concentration of hydroxide ions in the final solution:

moles of NaOH = moles of OH- ions produced = 0.027 mol
volume of final solution = 200 mL + 300 mL = 0.500 L

[OH-] = moles of OH- / volume of solution
[OH-] = 0.027 mol / 0.500 L
[OH-] = 0.054 M

Therefore, the hydroxide-ion concentration in the final solution is 0.054 M.

The answer is choice C.

What Is the Hydroxide-Ion Concentration in a Solution Formed by Combining