1. what is the energy change (in k) when the temperature of 20 g of water increa
ID: 578239 • Letter: 1
Question
1. what is the energy change (in k) when the temperature of 20 g of water increases by 10c A. 20-10x4, 18 B. 20 283x4.18 D. 20x 283x 4.18 C. 1000 1000 2. The lattice enthalpy values for lithium Auoride and calcium fluoride are shown below LiF(s) CaF2(s) Ar = +1022 kJ mol-1 Ar = +2602 kJ mol-I Which of the following statements help(s) to explain why the value for lithium fluoride is less than that for calcium fluoride? I. The ionic radius of lithium is less than that ofcalcium. IL. The ionic charge of lithium is less than that of calcium A. Ionly B. only C. I and II D. Neither I nor II When the solids Ba(OH)2 and NH,SCN are mixed, a solution is produced and the temperature drops. . Ba(OH)2(s) + 2NH4SCN(s) Ba(SCN)2(aq) + 2NHy(g) + 2H20(1) Which statement about the energetics of this reaction is correct? A. The reaction is endothermic and H is negative. B. The reaction is endothermic and /is positive. C. The reaction is exothermic and Ais negative. D. The reaction is exothermic and H is positive. 4. Which reaction occurs with the largest increase in entropy? A. B. C. D. Pb(NO3)2(s) + 2K1(s) PbI2(s) + 2KNOi(s) CaCOg(s) CaO(s) + CO2(g) 3H2(g)+N2(g)2NH3(g) H2(g) + 12(8)-2HI(gExplanation / Answer
1.C
q=msdT=20g x 4.18J/g0C x100C = 20 x 4.18 x 10J = 20 x 4.18 x 10 /1000 KJ
2.B
lattice energyincreases with increasing magnitude of charge on ions.
3.B
4.B CO2 gas is producing
If gases are producing or moles of gases increases, entropy increases.
if moles of gases are same on both sides no change in entropy.
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