When one mole of LiBr is dissolved in 1 kg of H2O, the concentration of the Br- is
1. 0.5 molal
2. 0.5 molar
3. 1.0 molal
4. 1.0 molar
You will have one mole of the bromide ion in one mole of solution, right?
umm... i'm not sure. are you telling me that i will?
Bob Pursley is telling you that you will.
Look up the definitions of molar and molal solutions.
To determine the concentration of Br- when one mole of LiBr is dissolved in 1 kg of H2O, we need to understand the concepts of molarity and molality.
Molarity (M) is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per liter of solution. The formula for molarity is M = moles of solute / volume of solution in liters.
Molality (m) is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per kilogram of solvent. The formula for molality is m = moles of solute / mass of solvent in kilograms.
In this case, we are given that one mole of LiBr is dissolved in 1 kg of H2O (which is the solvent). Since we are asked to find the concentration of Br-, we need to consider that one mole of LiBr dissociates into one mole of Li+ ions and one mole of Br- ions.
To find the concentration of Br- using molality, we can calculate the moles of Br- and then divide by the mass of water in kilograms (since it is the solvent).
1 mole of LiBr → 1 mole of Br-
Therefore, the concentration of Br- in this solution is 1 molal (1 mol of Br- per kg of H2O).
So, the correct answer is option 3: 1.0 molal.