NY Chemistry Regents Exam Jan 2023
During a laboratory activity, a student places 21.0 mL of hydrochloric acid solution, HCl(aq), of unknown concentration into a flask. The solution is titrated with 0.125 M NaOH(aq) until the acid is exactly neutralized. The volume of NaOH(aq) added is 18.5 milliliters. During this laboratory activity, appropriate safety equipment is used and safety procedures are followed.
61 Explain, in terms of ions, why the hydrochloric acid solution can conduct an electric current. [1]
Electric current is conducted through the flow of charged particles. HCl is a strong acid that dissociates in water to give H+ and Cl- ions.
Answer: The hydrochloric acid solution can conduct an electric current because it produces ions when dissolved in water. The movement of these ions can generate an electric current.
62 Determine the concentration of the HCl(aq) solution, using the titration data. [1]
Table T on the Reference Table gives the titration equation which is MaVa = MbVb where a stands for acid and b stands for base.
Ma = ?
Va = 21.0 mL
Mb = 0.125 M
Vb = 18.5 mL
Ma(21.0 mL)= (0.125 M)(18.5 mL)
Answer: Ma = 0.110M