Compound Z has a MW of 100. Your lab partner weighed 25 grams of compound Z and dissolved it in water to a final volume of 1 liter. What is the concentration of the solution expressed as molarity?

0.25 mol / L

Explanation:

Molarity, is the number of moles present in a liter of solution.

M = n / V

M = molarity (unit = mol / L or M)

V = volume of solution in liter (unit = L),

n = moles of solute (unit = mol),

Moles is given mass divided by the molecular mass,

Hence,

n = w / m

n = moles,

w = given mass,

m = molecular mass.

From the question,

The data given is as follows -

w = 25 g

m = 100 g/mol

V = 1 L

From the above data,

Moles are given as -

n = w / m

n = 25 / 100 = 0.25 mol,

Now, the molarity is given as,

M = n / V

M = 0.25 mol / 1 L

M = 0.25 mol / L