You want to convert your known number to moles first. This can be done by converting from particles to moles. We can use Avogadro's constant, 6.022*10^23, as there is that number of particles in one mole of any atom or molecule.
(2.00*10^23 particles)/(6.022*10^23 particles per mole) = 0.3321155762 moles of KClO3
From the equation, for every 10 moles of KClO3 consumed, there are 3 moles of P4O10 produced.
So,
0.3321155762 mol KClO3 * (3 mol P4O10/10 mol KClO3) = 0.09963467286 mol P4O10
Then, converting from moles to grams, the molar mass of P4O10 is 4(30.97) + 16(10) = 283.88 g/mol
0.09963467286 mol * 283.88 g/mol = 28.2842909315
To stay consistent with sig figs, we need to reduce this number to 3 sig figs.
The final answer is: 28.3 grams of P4O10 are produced.
J.R. S.
05/25/22