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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Richeyyy on September 19, 2021, 10:08:09 AM

Title: 2aluminums and 3 sulfurs, what does it mean?
Post by: Richeyyy on September 19, 2021, 10:08:09 AM

https://youtu.be/1AOt5DpUVrk?t=38 take a look at that, I understand the atomic masses and stuff, what does he mean by 2 aluminums and 3 sulfurs though? and how did he calculate the percentage at 1:15? Seems like a fun experiment

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Borek on September 19, 2021, 06:35:10 PM

Compound formula is Al₂S₃, which means two Al atoms combine with three S atoms to produce a molecule (or, when the compound is ionic, there are no molecules as such, but the elements still combine in the given ratio).

If you know atomic masses of Al and S and you know in what ratio they combine in a compound repeating these calculations is rather obvious.

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Richeyyy on September 19, 2021, 09:36:17 PM

oooh he was referring to aluminum sulfide, i thought about that as well but i was like no way, for some reason, anyway, thanks for that. So in this example, al+s forms al2s3 and that's how you calculate the perfect ratio? what about the percentage thing at 1:15 though? could you direct me to another site or a tutorial if the explanation is difficult?

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Borek on September 20, 2021, 03:15:02 AM

Google for chemical compound percent composition.

And watch capitalization in element symbols, no sane chemist will omit it as it leads to potential ambiguities.

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Richeyyy on September 20, 2021, 01:02:50 PM

I get it where the reaction produces only one chemical, but what about when a reaction produces 3 chemicals at once? Such as let's say kno3+sugar, 2 KNO3(s) + CH2O(s) → 2 KNO2(s) + CO2(g) + H2O(g)
I have no idea which one to calculate to get the perfect ratio

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Borek on September 21, 2021, 02:53:15 AM

Quote from: Richeyyy on September 20, 2021, 01:02:50 PM

I have no idea which one to calculate to get the perfect ratio

Ratio of what?

Percent composition is a property of a compound (or mixture), not of a reaction.

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Richeyyy on September 21, 2021, 08:47:47 AM

Quote from: Borek on September 21, 2021, 02:53:15 AM

Quote from: Richeyyy on September 20, 2021, 01:02:50 PM

I have no idea which one to calculate to get the perfect ratio

Ratio of what?

Percent composition is a property of a compound (or mixture), not of a reaction.

Sorry if I didn't mention, and thanks so much for all your help so far I really appreciate it, and regarding your question, it's actually a mixture, I want to figure out how to calculate perfect ratios for a reaction to happen (so that there would be just the right amount of molecules of each reactant, not too much and not too little, for the reaction to happen without any of the reaction's products being greater than the other), I think those are called stoichiometric ratios, right now I wanna learn how to calculate kno3+sugar perfect ratio, but I can't find out how:/

Title: Re: 2aluminums and 3 sulfurs, what does it mean?
Post by: Richeyyy on September 21, 2021, 08:48:05 AM

Right now that's a huge goal for me tbh