University:
University of Arizona
Course:
CHEM 141 | General Chemistry Lecture I
Academic year:

2017
Views:

118

Pages:

1
Author:

CloudMaster

In the following example, we are going to calculate the molar concentration of ions in the solution of calcium nitrate. The question is: What is the molar concentration of each ion present in a solution of calcium nitrate with a concentration of 0.025 M? Calcium nitrate consists of two different ions: calcium and nitrate. Therefore, the question is what will be the concentration of each of them in the aqueous solution of 0.25 Molarity. We are given the concentration of the compound used to make the solution (dye) and asked to determine the concentration of the ions in the solution. We can use a subscript to denote the concentration of each ion. In the chemical formula of a compound, we can determine the relative ion concentration. To do this, we need to know the molecular formula of the ionic compound. For example, calcium nitrate is composed of calcium ions. The oxidation number of calcium is +2. Is +2, and the nitrate ion is -1. The nitrate ions are -1, so the chemical formula will be - of nitrate to cancel the positive - of calcium. So, here we have a calcium nitrate chemical formula because there are two nitrate ions for each calcium ion. Each mole of calcium nitrate represents the association of one mole of calcium and two moles of nitrate and they have basically the same volume. Okay, so they are in the same solution. Okay, so we have one mole of calcium in a specific volume, and two moles of nitric in that same volume. So, a solution that is 0.025 molarity in calcium nitrate will be 0.025 molarity of calcium because we have just one mole. But there will be a point zero five molarity in nitrate because nitrate has two moles in that solution. So, in other words, we have the constant - the molarity of the solution, which is calcium nitrate point zero 25 moles divided by the volume. This is the conversion factor, and we know that in each mole of calcium nitrate, we have two moles of nitrate. So we can cancel this out. model with this mode, and now multiply two times point zero 25, and that will be the concentration of the nitrate ions in molarity in that solution. Okay, so for the calcium, the concentration will be 1.025 (1+0.025), because 1.2 + 0.025 is equal to 1.225. While the nitrate is 1.122 (1+0.122), so that's 2 times their concentration of the ionic compound itself. The concentration of Ledyard is twice that of the calcium ions, so we expect the concentration to be twice as high as calcium.