A 360mg sample of aspirin, C9H8O4, (molar mass 180g), is dissolved in enough water to produce 200mL of solution. What is the molarity of aspirin in a 50mL sample of this solution?

Molarity is 0.04M

Explanation:

First of all, let's determinate the moles of aspirin in that sample

Mass / Molar mass = Moles

360 mg = 0.360 g

0.360 g / 180 g/m = 0.002 moles

This moles that are included in 200 mL of solution, are also in 50 mL.

So molarity is mol/L

50 mL = 0.05 L

0.002 m / 0.05 L = 0.04M