Question

A chemist prepares a solution by adding 293 mgmg of K2Cr2O7K2Cr2O7 (MWMW = 294.19 g/molg/mol ) to a volumetric flask, and then adding water until the total volume of the contents of the flask reaches the calibration line that indicates 250 mLmL . Determine the molarity of the prepared solution.

Answer 1

Answer: The molarity of solution will be 0.00325 M

Step-by-step explanation:

Molarity : It is defined as the number of moles of solute present per liter of the solution.

Formula used :

`Molarity=(n* 1000)/(V_s)`

where,

n= moles of solute =
`\frac{\text{Given mass}}{\text{Molar mass}}`

given mass = 239 mg = 0.239 g (1g=1000mg)

moles of
`K_2Cr_2O_7=(0.239g)/(294.19g/mol)=8.12* 10^(-4)mol`

`{V_s}` = volume of solution in ml = 250 ml

Now put all the given values in the formula of molarity, we get

`Molarity=(8.12* 10^(-4)* 1000)/(250ml)=3.25* 10^(-3)mole/L`

Therefore, the molarity of solution will be 0.00325 M