How much heat is absorbed during production of 136 g of no by the combination of nitrogen and oxygen?

100.3kcal of heat will be absorbed. 2moles of NO absorb 43kcal. I mole of NO weighs 14 +16 = 30g so 2 moles weigh 60g. So 60g absorb 43kcal So 1g absorb 43/60 kcal So 136g absorb (43/60) x 136 = 97.47 kcal

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

Which of the following did you identify correctly