Question #bfaae

1 Answer
Mar 2, 2017

Answer:

a) #1.4 * 10^(-3)# M F
b) #1.14 * 10^13#g KF

Explanation:

Molarity is the number of moles per liter of solution. The molecular (atomic) weight of fluorine is 19g/mol, or 19000 mg/mol. 1.4mg F is #1.4 * 10^(-3)#g. Therefore, its molarity is #1.4 * 10^(-3)# M in this case.

To reach a #1.4 * 10^(-3)# M concentration of F in #1.4×10^8# L requires
#1.4×10^8# L * #1.4 * 10^(-3)# mol/L = #1.96 * 10^11# mol F
Delivered as KF, we would need the same number of moles of KF. Adding “K” to the “F” weight previously used, we have a molecular weight of 58g/mol. The amount of grams of KF that will need to be added is then
#1.96 * 10^11# mol * 58g/mol = #113.7 * 10^11#g , or #1.14 * 10^13#g KF