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4Na + O2 ---> 2Na2Ohttp://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Chemistry (9701)/9701_w12_qp_12.pdf
q:17 ... why can't i just cross multiply the number of moles for M? and then use n=mass/Mr to find Mr?
why does it give a different answer?
View attachment 57506
n of O2 = 0.0125mol (0.3/24)
so n of Na = 4* n pf O2
so n of Na = 0.05mol
Mass 0f Na = 1.15
Mr = 1.15/0.05 = 23.
Thats correct.