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Chemistry

I need help with the last few steps of question 1B), the question is in the link. https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Topic-Qs/AQA/Physical-I/1.2-Amount-of-Substance/Set-F/Balanced%20Equations%20&%20Associated%20Calc's%2001%20QP.pdf

I don’t know why you should multiply the moles you work out by 2/3
Original post by Watermelon11
I need help with the last few steps of question 1B), the question is in the link. https://pmt.physicsandmathstutor.com/download/Chemistry/A-level/Topic-Qs/AQA/Physical-I/1.2-Amount-of-Substance/Set-F/Balanced%20Equations%20&%20Associated%20Calc's%2001%20QP.pdf

I don’t know why you should multiply the moles you work out by 2/3

PV = nRT

150,000* 7.5*10^-2 = n * 8.31 * 308

11250 = 2559.48n

n = 11250/2559.48 = 4.40 moles of nitrogen

2NaN3(s) --> 2Na(s) + 3N2(g)

Since the sodium azide and nitrogen are in 2:3 ratio, divide 4.40 by 3 and multiply by 2

4.4 * 2/3 = 2.93 moles of Sodium azide.

Mole * Mr = Mass, 2.93 * 65 = 190.45g or 190.5g or 191g depends on how many d.p. or s.f. you prefer working with.

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