Acid is a proton donor and base is a proton accepter?

Question

first of all, please respond to this, i have a huge test tomorrow and would appreciate any help i can get!

According to the Bronsted- Lowry model, acid gives a proton in an acid reaction and the base takes the proton... well given this example...

HCl + H2O ----> H3O + Cl

if the HCL would be the acid, why isn't the Cl H2CL instead because the acid gives a proton.. and why isn't the H3O OH because it loses a proton..

where am i losing it?
also, what would the full name of these pairs be-- would the HCl and the Cl be conjugate acid base pairs?

thank you so much.

Answer 1

You're losing it in the equation.
HCl + H2O ==> H3O^+ + Cl^-
Now, HCl is the acid because you can see it has donated a proton to H2O. How do I know it donated a proton? Because on the right side of the equation, there Cl^- is by its lonesome, without the proton it had on the left side. So clearly, HCl has lost a proton. That makes HCl the acid and it makes Cl^- the conjugate base. Now, we had H2O on the left. On the right, it is H3O^+. Clearly, the H2O has gained a H^+ (accepted a proton) to become the hydronium ion. So H2O has acted as a base because it accepted a proton, the H3O^+ is the conjugate acid. And your definitions are correct.