A 13.9 mL solution of HCl is completely neutralized by titrating with 24.9 mL of 0.0100 M NaOH. What is the concentration of
the HCl solution?

HCI + NaOH --> H2O + NaCl

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.