When 3.75 g of a nonelectrolyte solute is dissolved in 405 mL of water at 25 °C, the resulting solution exerts an osmotic pressure of 897 torr.
What is molarity?
I found molarity to be 0.048.
What is the number of moles of solute?
to find moles, I multiplied it by .405 and got an answer of 0.019 moles, however, that's incorrect. What did I do wrong? Please help? Thanks!
M = mols/L or
mols = M x L = 0.04826 x 0.405 = 0.019545
I think you just reported too few significant figures in the answer. You are allowed three and you reported only two. Of course my answer has too many.
Well, it seems like you're trying to calculate the number of moles of solute, but your calculations went a bit awry. Let's see if we can straighten things out with a dash of humor, shall we?
First off, you're right about the molarity being 0.048 M. Good job on that one! Now, to find the number of moles, we can use the formula:
moles = molarity × volume (in L)
You have the molarity as 0.048 M, so all we need to do is convert the volume from mL to L. You said you multiplied by 0.405, but that's not quite right. You need to divide by 1000 to convert mL to L. Let me calculate it for you:
moles = 0.048 M × (405 mL ÷ 1000 mL/L)
And the answer is... drumroll, please! (Ba-dum-tss)
moles = 0.01954 moles
Ah, there we go! Approximately 0.01954 moles of solute. So it seems like you just missed a tiny division step. But don't worry, I'm here to help sprinkle a little laughter into the equation!
To determine the number of moles of solute, you need to use the formula for calculating osmotic pressure:
π = (n/V)RT
where π is the osmotic pressure, n is the number of moles of solute, V is the volume of the solution in liters, R is the ideal gas constant (0.0821 L atm/mol K), and T is the temperature in Kelvin.
First, convert the given temperature of 25 °C to Kelvin:
T = 25 + 273.15 = 298.15 K
Then, rearrange the formula to solve for the number of moles:
n = (πV)/(RT)
Now, substitute the given values into the formula:
n = (897 torr * 0.405 L) / (0.0821 L atm/mol K * 298.15 K)
Calculating this expression will give you the correct number of moles of solute.
To find the number of moles of a solute, we need to use the formula:
moles = mass ÷ molar mass
In this case, you have 3.75 g of the solute. However, you didn't mention the molar mass of the solute, which is necessary to calculate the number of moles accurately.
Once you have the molar mass of the solute, divide the given mass by the molar mass to find the number of moles.