A 14.3mL sample of a 15.0% solution of K2CrO4 has a density of 1.129g/cm³. The sample is diluted to a volume of 100.0mL. What is the molarity of the final solution? ( atomic weight:K=39.1,Cr=52.0,O=16.0)

Answer 1

First, we need to calculate the mass of K2CrO4 in the original 14.3mL sample:

Volume = 14.3mL
Density = 1.129g/cm³

Using the formula: Mass = Volume x Density
Mass = 14.3mL x 1.129g/cm³ = 16.1247g

Next, we need to calculate the moles of K2CrO4 in the original sample:

Molar mass of K2CrO4 = (39.1 x 2) + 52.0 + (16.0 x 4) = 194.1 g/mol

Moles = Mass / Molar mass
Moles = 16.1247g / 194.1 g/mol = 0.08318 moles

Now, we dilute this sample to a final volume of 100.0mL, which means the final solution contains 0.08318 moles of K2CrO4 in 100.0mL.

Molarity = Moles / Volume (in L)
Volume = 100.0mL = 0.1L

Molarity = 0.08318 moles / 0.1L = 0.8318 M

Therefore, the molarity of the final solution is 0.8318 M.