Answer: D) protons.
The other option that would make the most sense would be electrons, however the mass of an electron is so small that is basically negligible, so it's not included in the atomic mass.
The mass of NaN3 needed to produce 17.2 L nitrogen at STP is calculated as follows
find the moles of N2 produced at STP
At STP 1mole of gas = 22.4 L , what about 17.2 L of nitrogen
by cross multiplication
= (1 mole x17.2 L)/ 22.4 L= 0.768 moles
2NaN3 =2Na +3 N2
by use of mole ratio between NaN3 to N2 (2:3) the moles of NaN3 = 0.768 x2/3 = 0.512 moles of NaN3
mass of NaN3 is therefore =moles of NaN3 xmolar mass of NaN3
=0.512moles x 65 g/mol =33.28 grams of NaN3
The reaction is:
X + Y → W + Z
Chemical energy of reactant X = 199.3 J = Ux
Chemical energy of reactant Y = 272.3 J = Uy
Chemical energy of Product W = 41.9 J = Uw
Chemical energy of Product Z = ? = Uz
Where reaction loses energy = 111.6 J = ΔU
By using the equation:
(Ux + Uy) – (Uw + Uz) = ΔU
Ux + Uy – Uw – Uz = ΔU
Uz = Ux + Uy – Uw –ΔU
Uz = 199.3 + 272.3 – 41.9 – 111.6
Uz = 318.1 J
Product Z must contain 318.1 J chemical energy.
Right, left, same, left (will put the rest in comments)
