Question

The beaker shown below contains a 0.58 M solution of dye in water. How many moles of dye are there in the beaker?

Answer 1

Molarity is the number of moles that are contained in 1000 cm³ or a liter of water.
In this case the molarity is 0.58 M meaning 0.58 moles of the dye are contained in 1000 cm³ or a liter of water.
The beaker is at 150 cm³, there the number of moles will be;
=0.58 × 150/1000
= 0.087 moles

Answer 2

According to the equation of molarity:

Molarity= no.of moles / volume per liter of Solution

when we have the molarity=0.58 M and the beaker at 150mL so V (per liter) = 150mL/1000 = 0.150 L

by substitution:
∴ No.of moles = Molarity * Volume of solution (per liter)
= 0.58 * 0.150 = 0.087 Moles