Arthur is performing a lab which requires a 0.2 M solution of calcium hydroxide. However, the only calcium hydroxide solution available has a concentration of 0.5 M. How can Arthur dilute the 0.5 M solution to make 10 mL of a 0.2 M solution?
A.He needs to add 2.5 mL of the 0.5 M solution to 10 mL of water.
B.He needs to add 4 mL of the 0.5 M solution to 10 mL of water.
C.He needs to add 4 mL of the 0.5 M solution to 6 mL of water.
D.He needs to add 2.5 mL of the 0.5 M solution to 7.5 mL of water.
2 answers
The correct answer is not listed but the answer you're supposed to pick is c. The reason it isn't the correct answer is because you're assuming the 4mL adds to the 6 mL to make 10.0 mL solution. BUT solutions are not additive. c should say it this way. "He needs to add 4 mL of the 0.5 M solution to a container and add enough water to make 10.0 mL of solution."
A. he needs to add 4 mL of the 0.5 M solution to 6 mL of water.