Question

A chemist prepares a solution of sodium chloride (NaCI) by measuring out 68. umol of sodium chloride into a 200. mL volumetric flask and filling the flask to the mark with water. Calculate the concentration in mmol/L of the chemist's sodium chloride solution. Be sure your answer has the correct number of significant digits.

Answer 1

the concentration of the sodium chloride solution is 0.34 mmol/L, rounded to two significant digits.

Step-by-step explanation:

To calculate the concentration of the sodium chloride solution, we first need to convert the amount of NaCl from micromoles (umol) to moles (mol) using the following conversion factor:

1 umol = 1 × 10^-6 mol

So, 68. umol of NaCl is equal to:

umol x (1 mol / 1 × 10^6 umol) = 6.8 × 10^-5 mol

Next, we can use the formula for molarity to calculate the concentration of the solution:

Molarity = moles of solute / volume of solution in liters

The volume of the solution is given as 200. mL, or 0.200 L. Substituting the values we have calculated, we get:

Molarity = 6.8 × 10^-5 mol / 0.200 L = 0.00034 mol/L

Finally, we can convert the concentration from mol/L to mmol/L by multiplying by 1000:

0.00034 mol/L x 1000 mmol/mol = 0.34 mmol/L