Question

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

Answer 1

The molarity is 1.26
`( moles)/(L)`

Step-by-step 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=(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=(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=(0.063 moles)/(0.05 L)`

Molarity= 1.26
`( moles)/(L)`

The molarity is 1.26
`( moles)/(L)`