Salicylic acid (C₇H₆O₃) reacts with acetic anhydride (C₄H₆O₃) to form acetylsalicylic acid (C₉H₈O₄).

What is the limiting reactant if 70.0 g of C₇H₆O₃ and 80.0 g of C₄H₆O₃ react?

The limiting reactant is the Salicylic acid (C₇H₆O₃)

Explanation:

In order to find the limting reactant or the excess reactant of a chemical reaction we have to compare the moles of each reactant to the stoichiometry of the reaction; we usually make rules of three.

First of all we need to convert the mass of the reactants, to moles:

70 g / 138 g/mol = 0.507 moles of salicylic acid

80g / 102 g/mol = 0.784 moles of acetic anhydride

The reaction is: 2C₇H₆O₃ (aq) + C₄H₆O₃(aq) → 2C₉H₈O₄(aq) + H₂O(l)

Ratio is 2:1.

2 moles of salicylic acid need 1 mol of acetic anhydride to react

Then, 0.507 moles of salicylic will react with (0.507 . 1) / 2 = 0.254 moles of acetic anhydride (It's ok, I have 0.784 moles and I only need 0.254 moles, so acetic anhydride still remains, the C₄H₆O₃ is the excess reactant)

In conclussion, the limiting reactant is the Salicylic acid (C₇H₆O₃)

Let's verify: 1 mol of anhyride  needs 2 moles of salicylic acid

Therefore, 0.784 moles of anhydride  will react with (0.784 . 2) /1 = 1.57 moles. → We do not have enough C₇H₆O₃, we have 0.507 moles but we need 1.57.

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.