Question

Calculate the volume (liters) of solution that can be prepared from 180. grams of K2Cr2O7 for a 0.200M solution.

Answer 1

Answer:

The volume of the solution is 0.305 liters.

Explanation:

Molar mass is the amount of mass that a substance contains in one mole. The molar mass of K₂Cr₂O₇ is 294 g / mole. Then you can apply the following rule of three: if by definition of molar mass 294 grams of the compound are contained in 1 mole, 180 grams are contained in how many moles?

$moles=\frac{180 grams*1mole}{294 grams}$

moles= 0.61

Molarity is a measure of the concentration of a substance that is defined as the number of moles contained in a certain volume. So, the molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:

$molarity=\frac{number of moles of solute}{volume}$

Molarity is expressed in units $\frac{moles}{liter}$.

In this case:

• molarity= 2 M
• number of moles of solute= 0.61 moles
• volume= ?

Replacing in the definition of molarity:

$2 M=\frac{0.61 moles}{volume}$

Solving:

$volume=\frac{0.61 moles}{2 M}$

volume= 0.305 liters

The volume of the solution is 0.305 liters.