Percent Composition & Finding Formula - Chemistry

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Discussion Overview

The discussion revolves around determining the percent composition and formula of a sulfide formed from a reaction between sulfur and iron. Participants explore the steps involved in calculating the moles of each reactant and how to derive the empirical formula from the resulting ratios.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • One participant suggests converting the masses of sulfur and iron to moles to find the ratio of moles consumed, which would indicate the atomic ratio of sulfur to iron in the sulfide.
  • Another participant expresses uncertainty about how to divide the moles to obtain a fraction, indicating a need for clarification on this step.
  • A different participant notes that if the problem is done correctly, a recognizable ratio of small whole numbers should emerge, implying that this is a common outcome in such calculations.
  • One participant mentions using a specific calculator command to simplify the process of finding the ratio.

Areas of Agreement / Disagreement

Participants generally agree on the method of converting to moles and finding ratios, but there is uncertainty regarding the division of moles and how to express the result as a fraction.

Contextual Notes

Participants have not fully resolved the steps involved in converting decimal ratios to fractions, and there may be assumptions regarding the accuracy of the initial mass measurements and the completeness of the reaction.

Who May Find This Useful

Students studying chemistry, particularly those focusing on stoichiometry and empirical formula calculations, may find this discussion relevant.

Larrytsai
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% 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
 
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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.
 
Kalirren said:
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
 
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.
 

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