I think it would be because of the heat. (Swelling from the sun being on them for so long.) Hope I helped! :)
Actual yield over theoretical yield, then multiply by 100
Empirical formula of caffeine is C₈H₁₀N₄O₂.
In 1 mol of caffeine we have 10 mol of hydrogen.
In 2,8 mol of caffeine we have x mol of hydrogen.
x = 2,8 mol * 10 mol / 1 mol = 28 mol
ANSWER: There are 28 mol of hydrogen.
:-) ;-)