2. In each of the following cases, give the sign of q and w. If no work is done

Question

2. In each of the following cases, give the sign of q and w. If no work is done write System 2(s)2(g) H20(1) H2O(g) H20() H20(s) SO2(g)2H2S(g) 3S(s) 2H20(g)+heat ref: Ebbing and Gammon, General Chemistry. 8th Ed., Houghton Mifflin. New York. 2005. pg. 256) 270.3 kJH2(g) C(graphite) + N2(g) 2HCN(g) (ref: Ebbing and Gammon, General Chemistry: 8hEdk Houghton Miffin, New York, 2005 P9.256) Cl2(g) 2CI(g) N2(g) O2(g) 2NO(g) AH 180.6 kJ (ref: Ebbing and Gammon, General Chemistry 8 Ed Houghton Mifflin New York. 2005 pg 256) NaOH(aq) + HCI(aq) NaCl(aq) + H20)

Explanation / Answer

1) iodine solid to iodine gas, it is sublimation process, so it needs energy. Hence

Sign of q= +ve (positive)

Gas is in products and solid is in reactants. So it is expansion.

Hence sign of water= -ve(negative)

2) It also similar to first reaction. Hence

Sign of q= +ve

Sign of water= -ve

3) this reaction is water to solid ice so it is freezing process.

It releases energy.

Hence sign of q= -ve

Here no gases in reaction. So work done is zero

W= 0

4) In this reaction heat releases.

So sign of q= -ve

There are three gas molecules on reactants side and two gas molecules on products side. So this is compression.

Here work done on the system.

Hence sign w=+ve

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