# Homework Help: Finding mole and name of elements

1. Jun 5, 2010

### zainriaz

1. 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?

2. Relevant equations
NO. OF MOLES=given mass/molar mass

3. The attempt at a solution
molesof element M:moles of compound formed MF2
1 : 1
0.6 : 0.6
1 mole of MF2 contains 2 moles of F
0.6 MOLES WOULD CONTAIN=0.6*2=1.2

now i dnt no how can i find which element it is

2. Jun 5, 2010

### Staff: Mentor

Think how you can calculate its molar mass from the information given.

--
methods

3. Jun 5, 2010

### zainriaz

i tried my best i m nt getting which formula to use

4. Jun 5, 2010

### Tedjn

A little more: how much MF2 do you have at the end of your reaction?

5. Jun 6, 2010

### zainriaz

total MF2=46.8GMS
atomic mass of flourine=19 g/mol
mass=moles*atomic mass
=0.6*19
= 22.8gms
hence
mass of element M=46.8-22.8
=24gms
molar mass of element M=mass of M/moles of M
=24GMS/0.6
=40 g/mol
atomic mass of element M=40g/mol
this is atomic mass of calcium

6. Jun 6, 2010

### zainriaz

so the element is calcium

thnx a lot for ur help

7. Jun 6, 2010

### Staff: Mentor

Wasn't that hard :wink