Okay I know that as the temperature rises the number of particles in a given volume decreases. The molar volume likewise increases. So the number of molecules per liter would decrease as the temperature rises meaning that a 1M solution is only 1M at a specific temperature.
But why is molarity dependent on temperature? I mean sure the density does decrease as the temperature rises but still there is a small chance that the molarity will stay the same.
First, there is very very little chance it will remain same. Density will surely change with temperature.
Secondly, even if there is a small chance that it will remain same, then also there is an even greater chance that it will change.
So we will have to look at the general case and conclude that molarity depends on temperature.
We have n = M * volume of solvent. n = weight of compound / molecular weight. Weight of compound / Volume * mol. Weight = M. Density/ mol weight = M. Now since molecular weight of a compound is constant . We have density directly proportional to the Molarity. As you agree with the variation of density with temperature I am sure you agree to the change of Molarity also now.
