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### 15.13 Homework Question

Posted: **Wed Feb 22, 2017 11:20 am**

by **Jaime_Chamberlain_3G**

Can you please explain how to do 15.13 in the Homework? "When 0.52 g of H2 and 0.19 g of I2 are confined to a 750. -ml reaction vessel and heated to 700 K, they react by a second-order process (first order in each reactant), with k=0.063 L/molxs in the rate law for the rate of formation of HI. a) What is the initial reaction rate? b) What what factor does the reaction rate increase if the concentration of H2 present in the mixture is doubled? "

### Re: 15.13 Homework Question

Posted: **Wed Feb 22, 2017 11:44 am**

by **Armin Saber 3F**

I think you have to turn the grams of reactants into mol/L using PV=nRT. Then use Rate = k[H2][I2] (page 66 of reader) to solve for the reaction rate. With that equation you can see that doubling the H2 concentration would double the rate.

### Re: 15.13 Homework Question

Posted: **Wed Feb 22, 2017 7:20 pm**

by **Michelle_Li_1H**

To add on to that,

For part a, using the given mass of H2 and I2, you would divide by the molar mass to get the moles of H2 and I2. Then you would calculate the molarity of each using c=m/V.

Given the rate constant and the fact that both reactants are first order, we would plug in the concentrations and k into rate= k[H2][I2] to solve for the rate, and you should get 2.2*10^-5 mol/L*s.

For part b, you know that if the concentration of H2 doubles, then rate=k*2*[H2][I2], which would mean the rate would also double or increase by a factor of 2.

Hope this helps!