Question

What is the molariity of a 50.0 mL aqueous solution containing 10.0 grams of copper (II) sulfate, CuSO4?

Answer 1

Answer:

The molarity is 1.26 $\frac{ moles}{L}$

Explanation:

Molarity is a unit of concentration that is based on the volume of a solution and represents the number of moles of solutes contained in a liter. The molarity of a solution is calculated by dividing the moles of the solute by the liters of the solution and is expressed in units (moles / liter).

$Molarity=\frac{number of moles of solute}{Volume}$

You must calculate the number of moles of CuSO₄. So, being:

• Cu: 63.54 g/mole
• S: 32 g/mole
• O: 16 g/mole

the molar mass of CuSO₄ is

CuSO₄=63.54 g/mole + 32 g/mole + 4* 16 g/mole= 159.54 g/mole

Then it is possible to apply the following rule of three: if 159.54 g of CuSO₄ are present in 1 mole, 10 g in how many moles are they?

$moles=\frac{10 g*1 mole}{159.54 g}$

moles= 0.063 moles

Then:

• number of moles of solute= 0.063 moles
• Volume= 50 mL= 0.05 L (Being 1L=1000 mL)

Replacing in the definition of molarity:

$Molarity=\frac{0.063 moles}{0.05 L}$

Molarity= 1.26 $\frac{ moles}{L}$

The molarity is 1.26 $\frac{ moles}{L}$