Question

276 mg of salicylic acid, C₇H₆O₃, (molar mass 138 g/mol) is dissolved in enough water to make 100 mL of solution. What is the molarity of salicylic acid in a 25 mL sample of this solution?

Answer 1

The molarity of salicylic acid in a 25 mL sample of the solution is 0.08 M.

Step-by-step explanation:

To find the molarity of salicylic acid in a 25 mL sample of the solution, we first need to find the number of moles of salicylic acid in the solution. We can do this by dividing the mass of salicylic acid by its molar mass:

Moles of salicylic acid = mass of salicylic acid / molar mass of salicylic acid = 276 mg / 138 g/mol = 0.002 moles

Next, we calculate the volume of the 25 mL sample in liters:

Volume of 25 mL sample = 25 mL × (1 L/1000 mL) = 0.025 L

Finally, we use the formula for molarity:

Molarity = moles of solute / volume of solution in liters = 0.002 moles / 0.025 L = 0.08 M