what is the total grams of potassium fluoride (molar mass= 58g/mol) needed to make 9.4 liter of a 6.17 molarity solution ?

Answer 1

Hello, Madina,

Molarity is defined as moles per liter. 6.17 Molar means we have 6.17 moles of KF in every liter of the solution. Keep an eye on the units, and it becomes easier to see how this may be calculated.

(6.17 moles KF/liter)*(58 g KF/mole KF)*(9.4 liters) = 3364 grams. (or 3.364 kg)

The 58 g/mole only has 2 sig figs, but it could be be easily expanded to at least three. The 9.4 liters is also 2 sig figs, but it is a defined target, so if the actual measurement is to the ml, it would have 4 sig figs. Since none of these are measured values, it is appropriate to leave this at at least 4 sig figs, once the molar mass is determined more precisely. (e.g., 58.096 g/mole).

Bob