A student prepares 150.0 mL of 1.40 M HCl using 35.0 mL of a stock solution. What is the concentration of the stock solution?
Answer (1)
Use the dilution equation: M i V i = M f V f .
Rearrange the equation to solve for the initial concentration: M i = V i M f V f .
Plug in the given values: M i = 35.0 \t m L ( 1.40 \t M ) ( 150.0 \t m L ) .
Calculate the initial concentration: M i = 6.0 \t M .
The concentration of the stock solution is 6.00 M .
Explanation
Problem Analysis We are given the volumes and concentration of a diluted solution and asked to find the concentration of the original stock solution. We can use the dilution equation to solve this problem.
Dilution Equation The dilution equation is given by: M i V i = M f V f where: M i = initial concentration (stock solution) V i = initial volume (stock solution) M f = final concentration (diluted solution) V f = final volume (diluted solution)
Given Values We are given: V i = 35.0 \t m L V f = 150.0 \t m L M f = 1.40 \t M We need to find M i .
Rearrange Equation Rearrange the equation to solve for M i :
M i = V i M f V f
Calculate Initial Concentration Plug in the given values: M i = 35.0 \t m L ( 1.40 \t M ) ( 150.0 \t m L ) M i = 35 210 \t M M i = 6.0 \t M
Final Answer Therefore, the concentration of the stock solution is 6.0 M.
Examples
Dilution calculations are commonly used in chemistry, biology, and medicine. For example, a nurse might need to dilute a concentrated medication to the correct dosage for a patient. Similarly, a chemist might dilute a stock solution of acid to create a working solution for an experiment. Understanding dilution calculations ensures accurate and safe preparation of solutions in various fields.
