Question

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?

Answer 1

0.25 mol /L

Step-by-step 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