A sample of NI3 is contained in a piston and cylinder. The samples rapidly decomposes to form nitrogen gas and iodine gas, and releases 3.30 kJ of heat and does 950 J of work. What is ∆E?

-2.35 kJ

Explanation:

The energy change of the NI3 sample, ΔE = Q + W. where Q = quantity of heat and W = workdone. After decomposing to form nitrogen gas and iodine gas,  3.30 kJ of heat is released, Q = -3.30 kJ and since the sample does work of 950 J, W = +950 J = + 0.950 kJ.

ΔE = Q + W = -3.30 kJ + (+ 0.950 kJ) = -3.30 kJ + 0.950 kJ = -2.35 kJ

number of electrons for neutral cl