Does an acid add to the solute concentration?

[zogoto]

Say the boiling point of water goes up 1.8 degrees for every mole of solute per liter. What is the BP of a 1 M HCl solution? It seems that it should be 103.6, but aren't all the H+ ions attached to H2O molecules to make H3O+, so those don't increase the number of solute particles (so it's just Cl that causes the BP to go up)?

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[BerkReviewTeach]

Say the boiling point of water goes up 1.8 degrees for every mole of solute per liter. What is the BP of a 1 M HCl solution? It seems that it should be 103.6, but aren't all the H+ ions attached to H2O molecules to make H3O+, so those don't increase the number of solute particles (so it's just Cl that causes the BP to go up)?

H3O+ is an impurity in water, so it impacts the bp just like Cl-. The i value for HCl is 2, so the bp elevation would be deltaTbp = k x 2 x m (where m is molality).

In your hypothetical example, the bp would be 103.6 rather than 101.8.