Question #90e5d

1 Answer
Dec 5, 2014

I gave this a go and I got a number close to #50%#.

Let us name the two compunds #XO_A# and #XO_B#.

We know that the ratio of some element, let us say #X#, to oxygen in #XO_A# is #1:0.29#.

That is, for every #1g# of #X# we have #0.29g# of #O_A#. (1)

Now, taking into account the oxygen-to-oxygen ratio between #XO_A# and #XO_B# is #2:7#, we can say that

for every #2g# of #O_A# we have #7g# of #O_B# (2) or, for simplicity, for evey #1g# of #O_A# we get #3.5g# of #O_B#.

Therefore, using (1) and (2), we can say that

for every #1g# of #X# we have #0.29 * 3.5 g = 1.02g# #O_B# for the second coumpound.
An approximately #1:1# ratio of #X# and #O_B# in #XO_B# means that the percent composition of #X# to #XO_B# is

#percentcomposition = 1/(1+1) *100 = 50%#