[faizulhu]

There are two questions:

1.Calculate the entropy change that results from mixing 54.0 g of water at 273 K with 27.0 g of water at 373 K in a vessel whose walls are perfectly insulated from the surroundings.  Consider the specific heat capacity of water to be constant and equal to 4.18 J/(g.K).

Answer to 1: 3.5 J/K

2. 12. The reaction

A(g) + 2B(g) -> C(g) + D(g)

       is an elementary process.  In an experiment, the initial partial pressures of A and B are PA=0.60 atm and PB=0.80 atm.  When PC=0.20 atm, the rate of reaction, relative to the initial rate, is

       a. 1/48           b. 1/24                  c. ¾             d. 1/6

Answer to 2: d

I don't even know where to start question 1. I found the common temperature to be 306.3 K then tried to use S = ncln(T2/T1) for both water and adding them up but still didn't get the required answer. For question 2, I want to know how they found the answer to be 1/6.