Which of the following salts will react with acidic solutions and cause the formation of bubbles? A) Na₂CO₃, B) NaBr, C) HCOONa, D) Na₃PO₄, or E) NaI.
If something is reacting to form bubbles, that means that a gas is a product of that reaction. So, we need to figure out which one of our answer choices will react with an acidic solution like HCl, for example, to form a gas. Let’s first look through our answer choices and identify which ones will actually react with acids. We might be able to eliminate some of them if they don’t. Our first answer choice is sodium carbonate, which is a basic salt. Since acids react with basic salts, we would expect this one to react with an acidic solution.
Answer choice B is sodium bromide, which is a neutral salt. We know the salt is neutral because the bromine ion is the conjugate to the strong acid, HBr. And the conjugates of strong acids do not act as bases. Our next answer choice is sodium formate. Formate is the conjugate base to the weak acid, formic acid. So, sodium formate is a basic salt. Our next answer choice is sodium phosphate, which is also a basic salt. Our final answer choice is sodium iodide, which, like sodium bromide, is a neutral salt.
Of the answer choices, the neutral salts won’t react with an acid, so we can eliminate them now. Now, let’s see what our remaining answer choices, A, C, and D, will do when they react with an acidic solution like HCl. The first answer choice we’re looking at is sodium carbonate. When carbonates react with an acid, they form a salt, in this case NaCl, water, and carbon dioxide. Carbon dioxide is, of course, a gas. So, when it’s formed as some result of this reaction, there will be little bubbles of carbon dioxide that are produced.
So, it seems we found our answer. Sodium carbonate will react with an acidic solution to form bubbles, which are the little bubbles of carbon dioxide gas that are formed as a result of the reaction. The remaining answer choices, C and D, would both react with an acid to form the conjugate acid of the base and a salt. There would be no gas produced in either of these reactions. So, of the salts we were given, sodium carbonate is the only one that will react in an acidic solution to form bubbles.