A 2.30 m solution of urea (CO(NH2)2; FW= 60.0) in water has a density of 1.14 g/mL. Calculate the percent mass of urea in this solution?
Do you need the density? If that is a small m then it is molality and not molarity and I don't think the density is needed,
2.30 m = moles/kg solvent
mols = 2.30
grams = moles x molar mass = 2.30 x 60 = ??
Total mass of solution = 1000 g + g urea = xx.
percent = (grams urea/total mass)*100
Check my thinking. Check my work.
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To calculate the percent mass of urea in the solution, we need to determine the mass of urea and the mass of the entire solution.
First, let's find the mass of the solution:
Given the density of the solution is 1.14 g/mL, and the volume is 2.30 m, we can use the formula:
Mass of solution = Volume of solution x Density of solution
Mass of solution = 2.30 m x 1.14 g/mL
Mass of solution ≈ 2.622 g
Next, we need to calculate the mass of urea in the solution. To do this, we can calculate the mass of urea in 100 mL of the solution (since percent mass is usually expressed per 100 mL).
Given that the solution is 2.30 m, it means that there are 2.30 moles of urea in 1 liter of the solution.
Number of moles of urea in 100 mL (0.1 L) = 2.30 moles/L x 0.1 L
Number of moles of urea in 100 mL = 0.23 moles
Now, we need to find the mass of 0.23 moles of urea. We'll use the molecular weight (FW) of urea, which is 60.0 g/mol.
Mass of urea = Number of moles of urea x Molecular weight of urea
Mass of urea = 0.23 moles x 60.0 g/mol
Mass of urea = 13.8 g
Finally, we can calculate the percent mass of urea in the solution using the formula:
Percent mass of urea = (Mass of urea / Mass of solution) x 100
Percent mass of urea = (13.8 g / 2.622 g) x 100
Percent mass of urea ≈ 527.65%
So, the percent mass of urea in the solution is approximately 527.65%.