A biochemist carefully measures the molarity of salt in 14.0 mL of photobacterium cell growth medium to be 11.6 mM.

Question

Unfortunately, a careless graduate student forgets to cover the container of growth medium and a substantial amount of the solvent evaporates. The volume of the cell growth medium falls to 6.35 mL. Calculate the new molarity of salt in the photobacterium cell growth medium.
Be sure your answer has the correct number of significant digits.

Answer 1

To calculate the new molarity of salt in the photobacterium cell growth medium, we can use the formula:

M1V1 = M2V2

Where:
M1 = initial molarity = 11.6 mM
V1 = initial volume = 14.0 mL
M2 = final molarity (what we're trying to find)
V2 = final volume = 6.35 mL

Plugging in the values:

(11.6 mM)(14.0 mL) = M2(6.35 mL)

162.4 mM⋅mL = 6.35 M2
M2 = 25.6 mM

Therefore, the new molarity of salt in the photobacterium cell growth medium is 25.6 mM.