Fundamentals G21

[TJ Lai 2H]

Hi everyone,

G21 asks us to find the molarity of potassium and sulfide ions in a solution is prepared by dissolving 0.500 g of KCl, 0.500 g of K2S, and 0.500 g of K3PO4 in 500 mL of water.

I know the molarity equation is (moles of solute) / (volume of solution).

For this problem, shouldn't the volume of the solution be 500mL water + volume(0.500 g KCl) + volume(0.500 g K2S) + volume(0.500 g K3PO4)? But are we able to calculate the volume of KCl, K2S, and K3PO4 given the info we have? Or should we assume that 1.5 g of solute is negligible for the total volume of the solution?

[VSU_3F]

In this case, the grams of solute don't contribute to the overall volume, so it's negligible. Therefore, 500 mL is the total volume of this solution.

[Rachel Jiang 3H]

Yes, I agree that the mass of solutes is negligible since they are really small so you should just use 500 mL as the volume of solution.

[Alessia Renna 1D]

The volume would be the 500 mL of water, usually volume in dilution equations will be in L or mL