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How many moles of solute are contained in a 250.0-milliliter solution that has a concentration of 0.85 M?


210 moles

0.21 moles

3.4 moles

0.29 moles

0.85 moles

Verified Answer :

Answer : The correct option is, 0.21 moles

Solution : Given,

Molarity of the solution = 0.85 M = 0.85 mole/L

Volume of solution = 250 ml = 0.25 L     \((1L=1000ml)\)

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

Formula used :

\(Molarity=\frac{\text{moles of solute}}{\text{Volume of solution in liters}}\)

Now put all the given values in this formula, we get the moles of solute of the solution.

\(0.85mole/L=\frac{\text{moles of solute}}{0.25L}\)

\(\text{moles of solute}=0.2125=0.21moles\)

Therefore, the moles of solute is, 0.21 moles

Answer: Option (b) is the correct answer.

Explanation:

It is known that molarity is the number of moles present in liter of solution.

Mathematically,    Molarity = \(\frac{\text{no. of moles}}{\text{volume in liter}}\)

It is given that volume is 250 mL or volume in liter will be 0.25 L (as 1 L = 1000 mL) and molarity is given as 0.85 M.

Therefore, calculate the number of moles of the solute as follows.

          Molarity = \(\frac{\text{no. of moles}}{\text{volume in liter}}\)

                 0.85 M = \(\frac{\text{no. of moles}}{0.25 L}\)      

                no. of moles = 0.21 mol

Therefore, we can conclude that 0.21 moles of solute are contained in a 250.0-milliliter solution that has a concentration of 0.85 M.

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