The density of a 40.0% by weight aqueous solution of NaOH is 1.432 g/cm3 what is the molarity of NaOH?
g NaOH = 1.432 g/cc x 1000 cc x 0.40 = ?g
mols = ?g/molar mass
M = mols/L
To find the molarity of NaOH in a 40.0% by weight aqueous solution, we need to use the given information about the density.
First, let's convert the given density from grams per cubic centimeter (g/cm^3) to grams per milliliter (g/mL), as the latter is a more commonly used unit for volume measurements in chemistry.
Since 1 cm^3 is equal to 1 mL, we can say that 1 g/cm^3 is equal to 1 g/mL.
Therefore, the density of the solution is 1.432 g/mL.
Next, we need to find the mass of NaOH in the solution.
Since the solution is 40.0% by weight, it means that 100 g of the solution contains 40 g of NaOH.
Let's assume we have 1 liter (1000 mL) of the solution to make calculations easier.
So, we can say that in 1000 mL of the solution, we have 400 g of NaOH.
Now that we have the mass of NaOH in grams and the volume of the solution in milliliters, we can calculate the molarity.
Molarity (M) is defined as the number of moles of solute per liter of solution.
To calculate the molarity, we need to find the number of moles of NaOH.
To do this, we need the molar mass of NaOH. The molar mass of Na is approximately 22.990 g/mol, and the molar mass of O is approximately 16.00 g/mol, while the atomic mass of H is approximately 1.008 g/mol.
Adding these together, we get a molar mass for NaOH of 39.998 g/mol (approximately 40 g/mol).
Now, we can calculate the number of moles of NaOH.
moles = mass / molar mass
moles = 400 g / 40 g/mol
moles = 10 mol
Finally, we can find the molarity by dividing the number of moles by the volume in liters.
molarity (M) = moles / volume (in liters)
Since we assumed a volume of 1 liter (1000 mL) earlier, the molarity of the 40.0% by weight solution of NaOH is:
M = 10 mol / 1 L
M = 10 M (moles per liter)
Therefore, the molarity of NaOH in the solution is 10 M.