A student weighs out a 14.4 g sample of copper(II) bromide, transfers it to a 500 mL volumetric flask, adds enough water to dissolve it and then adds water to the 500 mL tic mark.
What is the molarity of CuBr2 in the resulting solution
The answer I keep getting is completely wrong and I am unsure why.
I keep getting .229 Mol
To bad you didn't show how you got that number. I could have looked at it and found the problem.
mols CuBr2 = gams/molar mass = ?
Then M = mols/0.5L = ?
To find the molarity of CuBr2 in the resulting solution, we need to use the formula:
Molarity (M) = moles of solute / volume of solution (in liters)
First, let's calculate the moles of CuBr2 in the 14.4 g sample.
The molar mass of CuBr2 is calculated by adding the molar masses of copper (Cu) and bromine (Br) together:
Cu: 1 * 63.55 g/mol = 63.55 g/mol
Br: 2 * 79.90 g/mol = 159.80 g/mol
Molar mass of CuBr2: 63.55 + 159.80 = 223.35 g/mol
Now, divide the mass of the sample (14.4 g) by the molar mass of CuBr2 to get the moles:
Moles = mass / molar mass
Moles = 14.4 g / 223.35 g/mol
Moles ≈ 0.0644 mol
Next, we need to find the volume of the solution in liters (L). The 500 mL volumetric flask is equivalent to 0.5 L (since 1 L = 1000 mL).
Plugging in the values into the molarity formula:
Molarity (M) = moles / volume
Molarity = 0.0644 mol / 0.5 L
Molarity ≈ 0.129 M
So, the molarity of CuBr2 in the resulting solution is approximately 0.129 M.
If you are getting a different answer, make sure you double-check your calculations, especially dividing the mass by the molar mass and using the correct volume in liters.