Question

Calculate the molarity of the Co^2+ ion in each of the solutions 1-5. The new molarity is given by the molarity of the stock solution multiplied by the dilution factor.

Solution: Co(NO3)2

Original molarity: 0.160

Dilution #1: none
D#2: 12mL to 16mL
D#3: 8mL to 16mL
D#4: 4mL to 16mL
D#5: 2mL to 16mL

Please help I do not understand what I'm supposed to do. Thank you.

Answer 1

The problem is giving you 0.150M as the molarity and it tells you the new molarity will be the old one (0.160) x the dilution factor). After diluting, the first one will be 0.160 x (12mL/16mL)

The next one is 0.160 x (8 mL/16 mL).
However, from the way the problem is states I think it wants you to write the new molarity as the old molarity x the FACTOR. The dilution factor for the first one is (12/16) = 3/4; therefore, the first one will be
0.160 x (3/4), which of course is exactly the same answer as 0.160 x (12/16) but 3/4 is the dilution factor.

Answer 2

Okay, but what does it mean "Calculate the molarity of the Co^2+ ion in each of the solutions 1-5"