Final answer:
The molar concentration of hydrochloric acid (HCl) that is neutralized by potassium hydroxide (KOH) is calculated to be 0.197 M, which matches option C given the 1:1 reaction stoichiometry and provided volumes and molarities.
Step-by-step explanation:
The student is asking about the molar concentration of hydrochloric acid (HCl) that is neutralized by potassium hydroxide (KOH). To find the concentration of the HCl, we can use the fact that HCl and KOH react in a 1:1 mole ratio, as shown in the balanced chemical equation: HCl + KOH → KCl + H₂O.
To calculate the concentration of HCl, we need to first find the number of moles of KOH used during neutralization. Since we know the volume and concentration of KOH, we can calculate the moles of KOH using the formula:
moles of KOH = volume of KOH × molarity of KOH
moles of KOH = 54.2 cm³ × 0.166 mol/L = 8.996×10⁻³ mol
Because the reaction ratio is 1:1, the moles of HCl will equal the moles of KOH. So moles of HCl = 8.996×10⁻³ mol. Now, we can find the molarity (M) of the HCl by dividing the moles of HCl by the volume of HCl:
Molarity of HCl = moles of HCl / volume of HCl
Molarity of HCl = 8.996×10⁻³ mol / 45.6 cm³
Since we need the volume in liters for molarity calculations:
Molarity of HCl = 9.996×10⁻³ mol / 0.0456 L = 0.197 M
Therefore, the molar concentration of hydrochloric acid is 0.197 M, which corresponds to option C.