## anonymous one year ago If you burn 42.7 g of hydrogen and produce 382 g of water. How much oxygen reacted?

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1. Jhannybean

$\color{red}{\sf 2H_2~(g)~ + ~O_2~(g) ~\rightarrow 2H_2O~(l)}$You can either use the 42.7 g $$\sf H_2$$ or you can use the 382 g $$\sf H_2O$$ to find how much $$\sf O_2$$ was used due to The Law of Conservation of Mass in a chemical reaction. It will approximately give you the same result. $\sf 382 ~g~ H_2O ~ -~42.7~g ~H_2 = 339~g ~O_2$ Let's check this using Stoichiometry. $\sf 42.7~g~ H_2 ~\times~ \frac{1~mol~H_2}{2.02~g~ H_2} ~\times~ \frac{1~mol~O_2}{2~mol~H2}~\times~ \frac{31.9~g~O_2}{1~mol~O_2} \approx 338 ~g~O_2$$\sf 382~g~H_2O~\times~\frac{1~mol~H_2O}{18.0~g~H_2O}~\times~\frac{1~mol~O_2}{2~mol~H_2O}~\times~\frac{31.9~g~O_2}{1~mol~O_2}~\approx 339~g~ O_2$ So you could see that they pretty much give you the same result when you subtract the two amounts.

2. Jhannybean

@Shalante