What is the molarity of 250 mL of a solution that contains 12.5 g of dissolved zinc bromide, ZnBr2?
moles = grams/molar mass.
Solve for moles.
M = moles/L. Solve for M.
0.2
To find the molarity of a solution, we need to know the moles of the solute (ZnBr2) and the volume of the solution in liters (L).
1. Start by calculating the number of moles of ZnBr2:
The molar mass of ZnBr2 = (atomic mass of Zn) + 2 × (atomic mass of Br)
The atomic mass of Zn = 65.38 g/mol and the atomic mass of Br = 79.90 g/mol
Molar mass of ZnBr2 = 65.38 + 2 × 79.90 = 224.18 g/mol
Moles of ZnBr2 = Mass of ZnBr2 / Molar mass of ZnBr2
= 12.5 g / 224.18 g/mol
2. Convert the volume of the solution from milliliters (mL) to liters (L):
Volume of solution in L = 250 mL / 1000 mL/L
= 0.250 L
3. Calculate the molarity (M) of the solution:
Molarity (M) = Moles of solute / Volume of solution in L
= (12.5 g / 224.18 g/mol) / 0.250 L
Simplifying the expression, we get:
Molarity (M) ≈ 0.223 M
Therefore, the molarity of the solution containing 12.5 g of ZnBr2 in 250 mL is approximately 0.223 M.