Question

A chemist prepares a solution of potassium dichromate K2Cr2O7 by measuring out 3.46μmol of potassium dichromate into a 50.mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in /mmolL of the chemist's potassium dichromate solution. Round your answer to 2 significant digits.

Answer 1

Answer: 0.069 mmol/L

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

$Molarity=\frac{n\times 1000}{V_s}$

where,

n= moles of solute  = $3.46\mu mol$ =  $0.001\times 3.46=3.46\times 10^{-3}mmol$

1micro (µ) = 0.001 milli (m)

$V_s$ = volume of solution in ml= 50 ml

$Molarity=\frac{3.46\times 10^{-3}\times 1000}{50ml}=0.069mmol/L$

Thus concentration in mmol/L of the chemist's potassium dichromate solution is 0.069.