Question

1) If 0.33 mg of KCl is present in 1.0 L of aqueous solution, what is the concentration in terms of the following?

A) Molarity

B) weight/volume percent

C) parts per thousand

D) parts per million

2) The serum concentration of cortisol, a hormone, is expected to be in the range 8–20 mg/dL. What is the part per million concentration of cortisol in serum that contains 10 mg of cortisol per deciliter?

3)How many milliequivalents of bicarbonate ion (HCO₃^- ) are present in a 79.3 mL blood serum sample with a concentration of 26 mEq/L HCO₃^- ?

4)How many equivalents of calcium ion (Ca²⁺) are present in a 70 mL blood serum sample with a Ca²⁺ concentration of 3.3 mEq/L? Enter your answer in scientific notation.

5) How many moles of sodium ion (Na⁺) are present in a 15.8 mL blood serum sample with a Na⁺ concentration of 131 mEq/L?

Answer 1

Ans 1.

A)

Molarity = number of moles / volume of solution in L

Molar mass of KCL =74.5513 g/mol

0.33 mg = (0.33 x 10^-3) / 74.5513 = 4.43 x 10^-6 moles

So molarity = ( 4.43 x 10^-6) / 1 = 4.43 x 10^-6 M

B)

weight / volume percent = mass of solute in g / volume of solution in mL ) x 100

= [(0.33 x 10^-3) / 1000 ] x 100

= 0.33 x 10^-4 %

C)

parts per thousand = (mass of solute / mass of solution) x 1000

= [(0.33 x 10^-3) / 1000] x 1000

= 0.33 x 10^-3 parts per thousand

D)

parts per million = (mass of solute / mass of solution ) x 1000000

= [(0.33 x 10^-3) / 1000 ] x 10⁶

= 0.33 parts per million