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# If NI3 explodes according to the following equation, how many moles of NI3 are required to fill a 3L container at STP?

2NI3(solid) --> N2(gas) + 3I2(solid)

I am unsure how to solve this problem.  If I use the ideal gas equation (without referencing the chemical equation given), I get 0.134 mol NI3.  However, I don't think I am doing this correctly because I didn't use the equation given and NI3 is a solid and not a gas...  Please help me solve this!  Thank you so much!

Liz, you are very close.

With 0.134 L you have calculated the number of moles of N2 gas you need to fill a 3 L container at STP. The equation tells you that every 2 moles of NI3 gives you 1 mole of N2. That means you need twice as much NI3. Multiply your answer by 2 to get the number of moles of NI3 that produces the necessary amount of gas:

0.268 moles of NI3

Or, with significant figures of the question: 0.3 moles.

Use molar ratio: 2 moles of NI3 can produce 1 mole of N2.

Now use dimenstional analysis:

(3L)(1 mole of N2/22.4 L)(2 moles of NI3/1 mole of N2) = 0.268 moles of NI3.

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Attn: What you got is the number of moles of N2, not NI3. You have to use the chemical equation to get the molar ratio.