Mystical alternative view over Ljubljana, Slovenia; on a hill part of Golovec overlooking the city's south part
One of the most easy exercises in chemistry is calculating concentrations of solutions. However, for a lot of starting students or people new in the field, it remains a hassle to carry out such exercise. Let's say we want to prepare a 0,250 M aqueous solution of calcium chloride (CaCl2). CaCl2 is a white powder at room temperature. It dissolves readily in water. The exercise is as follows: What mass of CaCl2 is required to prepare a 300,0 mL of a 0,250 M solution? (Molecular mass of CaCl2 = 110,98 g/mol) Approach this step by step. First, deduct what is expected. 1. We need to calculate the amount of mass needed. Mass is in gram (g). The solution has a concentration of 0,250 M. This means we want a concentration of 0,250 Molar or = mol/liter. 2. 0,250 mol/liter. But we do not want 1 liter, we want 300 milliliter, or 0,3 liter. Calculate the amount of mol we need: 0,250 mol/liter to 300 milliter, I calculate it as follows: 0,250 mol divide by 1000 (1 liter = 1000 mil