finding moles and name of the element?

The problem statement, all variables and given/known data

a sample of 0.6 moles of a metal M reacts completely with excess of flourine to form 46.8 gms of MF2.

a)how many moles of F are present in the sample of MF2 that forms?

b)which element is represented by the symbol M?

Flourine = F2

F = -1

The charge of M = +2

M + F2 → MF2

This balanced equation states that 1 mole of M reacts with 1 mole of F2 to produce 1 mole of MF2

So, 0.6 moles of M reacts with 0.6 mole of F2 to produce 0.6 mole of MF2

46.8 g = 0.6 mole of MF2

1 mole of MF2 has a mass of 46.8 / 0.6 = 78 grams

1 mole of F2 = 38 grams

0.6 moles of F2 = 0.6 * 38 = 22.8 grams

46.8 – 22.8 = 24 grams of M

The 24 grams of M = 0.6 mole of M

1 mole of M = 24/0.6 = 40 g

Look on the periodic table for a metal (left side) with molar mass = 40 g and charge = +2.

Calcium

A) The number of moles of F would just be the molar ratio of 1:2

moles F = 2(0.6 moles M)

Moles F = 1.2

B) Molecular weight of compound

Since MF2 is produced on a 1:1 basis of M, and 0.6 moles of M are used, then 0.6 moles MF2 produced

Molecular Weight of MF2 = (46.8 g) / 0.6 moles

MW = 78 g/mole, which is represented by 2 fluorines and 1 M

MW of 2 fluroines = 2 (19.0) = 38.0

MW of M = 78 - 38

MW of M = 40.0 g/mol

An element with atomic weight of 40 = Ca