One of the most acidic lakes in the United States is Little Echo ...

Question

One of the most acidic lakes in the United States is Little Echo Pond in the Adirondacks in New York. Recently, this lake had a pH of 4.2, well below the recommended pH of 6.5. (10.6, 10.7) c. One way to raise the pH (and restore aquatic life) is to add limestone (CaCO₃). How many grams of CaCO₃ are needed to neutralize 1.0 kL of the acidic water from Little Echo Pond if the acid is sulfuric acid?H₂SO₄(aq) + CaCO₃(s) → CO₂(g) + H₂O(l) + CaCO₄(aq)

Accepted Answer

Hey, everyone. We're told that the river Bana heat originates from the world's largest acidic lake in the crater of Kawa Ian volcano. A sample of the river water has been taken and observed to have a ph of 3.3 far below the normal p range of 6 to 8 for stream water, determine how many grams of calcium hydroxide can neutralize a mL river water sample if the acid in the river is sulfuric acid and they provided us with the chemical equation of calcium hydroxide in its solid state plus sulfuric acid in its aqueous state. And the products are going to be calcium sulfate in its solid state plus water in its liquid state. Now, before we answer this question, let's first check if our chemical equation is balanced and we can do so by counting the number of elements in both our reactant and our product side. Starting with our reactant side. We can see that we have one of calcium, we also have six of oxygen, four of hydrogen and one of sulfur. Looking at our product side, we have one of calcium, five of oxygen, two of hydrogen and one of sulfur. So it looks like our chemical equation is not balanced. In order to balance this out, we can go ahead and add a coefficient of two prior to our water. This will change the number of oxygens into six in our product side and the number of hydrogens in our product side into four. Now, our chemical equation is completely balanced out. So first, let's go ahead and determine the concentration of our hydrogen ion. And we can do so by using our P H, now we know our P H is equal to the negative log of the concentration of our hydrogen ion. Now, to solve for our concentration of hydrogen ion, we would have to take the antilogue of the negative P H. So plugging this in, we get the anti log of negative 3.3, which is our P H and this gets us to a concentration of 5.11872 times 10 to the negative four molar. So the reason why we wanted to calculate for the concentration of our hydrogen ion is because sulfuric acid is a strong acid. So this dissociates completely. So the concentration of our hydrogen ion is also the concentration of our sulfuric acid. Now let's go ahead and solve for the grams of calcium hydroxide. And we can do so by using dimensional analysis starting with 5.11 872 times 10 to the negative four mole of sulfuric acid over liters of sulfuric acid. Next, we want to look at our multiple ratios between our sulfuric acid and our calcium hydroxide. Looking at our balanced chemical equation, we can see that one mole of sulfuric acid is equivalent to one mole of calcium hydroxide. Next, looking for the molar mass of calcium hydroxide. We know that we have 74.9 g of calcium hydroxide per one mole of calcium hydroxide. Next, we want to get rid of our liters of sulfuric acid and we can do so by using the mL of sulfuric acid solution provided to us in our question stem. But first, let's go ahead and convert our liters into milliliters. Now, we know that we have 10 to the negative third liters of sulfuric acid per one mL of sulfuric acid. And to get rid of our milliliters of sulfuric acid, we know that we have 50 mL of sulfuric acid solution. So when we calculate this out and cancel out all of our units, we end up with 1.9 times 10 to the negative three g of calcium hydroxide. And this will be our final answer. Now, I hope this made sense and let us know if you have any questions.

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