what is the molarity of 40g in 0.5L of solution. Molecular weight of substance is 100.09g/mole.
moles = grams/molar mass
M = mols/L soln.
Please be aware that this assumes the complete solubility of the substance in water. Just looking at the molar mass, the "substance" appears it may be CaCO3 and 40.0 g CaCO3 will not dissolve in 0.50 L H2O.
Okay, so this was a question on a quiz and I'm not sure if we were to just assume that it was dissolved? But the moles of CaCO3 is .4 correct?
Yes. 40.0g of a substance with molar mass of 100.09 = 0.4 mol of that substance.
If the question on the quiz was as you quoted it (a "substance" and it was not identified as CaCO3) then M = 0.40 mols/0.50 L and if you worked it that way you worked it correctly. When a problem is stated that way we generally assume it is completely soluble. If the substance was identified as CaCO3, it is a little more complicated than that since CaCO3 is so insoluble and it really turns into a Ksp problem. .
Thank You! You have answered a couple of my questions and I wish I had you for my Professor as mine seems to expect knowledge and not want to teach it! (haha but not really funny!) Thanks again!
Thank you. Post anytime. It helps if you explain exactly what you don't understand about something.
To calculate the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters).
First, you need to determine the number of moles of the substance present in the solution. This can be done using the formula:
Number of moles = Mass of substance (in grams) / Molecular weight of substance (in grams per mole)
In this case, the mass of the substance is given as 40 grams, and the molecular weight is 100.09 g/mole. Plugging these values into the formula, you get:
Number of moles = 40 g / 100.09 g/mole
Next, you need to calculate the volume of the solution in liters. Here, the volume is given as 0.5 liters.
Now, you can calculate the molarity of the solution using the formula:
Molarity = Number of moles / Volume of solution
Plugging in the values we have:
Molarity = (40 g / 100.09 g/mole) / 0.5 L
Now, you can simplify and calculate the molarity:
Molarity ≈ 0.399 M
Therefore, the molarity of the solution is approximately 0.399 M.