Percent Composition & Finding Formula - Chemistry

[Larrytsai]

% Composition & Finding Formula - Chemistry

50.0g of Sulphur is mixed with 100.0g of iron and heated strongly. When the reaction is complete 12.5g of iron remains. What is the formula of sulphide formed?

duno where to start

 

[Kalirren]

Convert everything to moles. Find the ratio of (moles sulphur consumed) to (moles iron consumed). That should give you the atomic ratio of sulphur to iron in the sulphide, which translates easily to a formula.

In general, "convert everything to moles" is a good first step.

 

[Larrytsai]

Convert everything to moles. Find the ratio of (moles sulphur consumed) to (moles iron consumed). That should give you the atomic ratio of sulphur to iron in the sulphide, which translates easily to a formula.

hmmm kk well where i get lost is when i divide the moles.
What i would do is divide big/small and get a decimal number but i don't knw how to convert that into a fraction

 

[Kalirren]

Generally, if you did the problem correctly, a pretty obvious and easily recognizable ratio of small whole numbers will turn out. Just do it and then see.

Admittedly, I always just used the ->frac command on my calculator.