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HSC Stuff => HSC Science Stuff => HSC Subjects + Help => HSC Chemistry => Topic started by: Droolv on May 19, 2016, 06:52:25 pm

Title: Calculating amount of Molecules needed??
Post by: Droolv on May 19, 2016, 06:52:25 pm
Hi, I'd love some help with this question:

Calculate the number of nitrogen molecules needed to react with oxygen to produce 3.5x10^21 molecules of N2O5

Thanks so much in advance :)
Title: Re: Calculating amount of Molecules needed??
Post by: JellyBeanz on May 19, 2016, 07:05:51 pm
Quote from: Droolv on May 19, 2016, 06:52:25 pm
Hi, I'd love some help with this question:

Calculate the number of nitrogen molecules needed to react with oxygen to produce 3.5x10^21 molecules of N2O5

Thanks so much in advance :)


Begin by writing a balanced equation for this reaction. This would be 2N2 + 5O2 ---> 2N2O5

Then since you're given the number of molecules of 2N2O5 you can find out the number of moles of 2N2O5 present using the relation N(number of particles) = n(number of moles) * Na(avogadro's number)

Using this n(number of moles) = 3.5*10^21 / 6.02* 10^23
                                                  = 5.81 * 10^-3 moles of 2N2O5

Now that you have the number of moles, use mole to mole ratios to calculate the number of mole of nitrogen molecules. Therefore the number of moles of nitrogen molecules is = 5.81 * 10^-3 (since there are two moles of 2N2O5 produced for every 2 moles of nitrogen molecules)

Now that you have the number of moles of nitrogen molecules, Use N = n * Na to find the number of nitrogen molecules. N = 5.81 * 10^-3 * 6.02 * 10^23 this is = to 3.5* 10^21. So it's the same amount of nitrogen molecules required to produce 2N2O5
Title: Re: Calculating amount of Molecules needed??
Post by: Droolv on May 19, 2016, 07:35:43 pm
Thanks so much :) I did a couple more questions and got them right
Title: Re: Calculating amount of Molecules needed??
Post by: JellyBeanz on May 19, 2016, 07:51:13 pm
No problem, make sure to ask more questions if you need help XD

Also, there is already a chemistry question thread in the HSC board where we have a lot of friends who would be happy to help you out :). If you have any further questions i'd advise you to post them here

Chemistry Question Thread

Glad to see you are getting the hang of these types of questions :)