Question

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

Answer 1

The volume of the solution is 0.305 liters.

Step-by-step 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=(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=(number of moles of solute)/(volume)`

Molarity is expressed in units
`(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=(0.61 moles)/(volume)`

Solving:

`volume=(0.61 moles)/(2 M)`

volume= 0.305 liters

The volume of the solution is 0.305 liters.