Hess's Law

I am having trouble with a question in my homework. It states: Given the following thermochemical equations 2KCl(s) + 3O2(g) .......2KClO3(s) Change in H = 78.0kJ P4(s) + 6Cl2(g)..........4PCl3(g) Change in H = -1148.0kJ P4(s) + 2O2(g) + 6Cl2(g).........4POCl3(g) Change in H = -2168.8kJ Calculate change in H for the reaction KClO3(s) + 3PCl3(g)..........3POCl3 + KCl(s) I know I am suppossed to combine the 3 thermochemical equations to come out with the above reaction. My problem is that I've tried every possible combination and still can't come up with this recaction. Could you help get me started with this a... click for more

Heat and Heats of Formation

This is a 2 part question I have for homework and I am completely lost. The question states: Given 2BaCO3(s) ---> 2Ba(s) + 2C(s) + 3O2(g) Change in H = 2432.6kJ First they ask for me to determine the heat of formation of BaCO3. My problem is how do you determine the heat formation of the reactant (in this case) when you are given a change in H for the whole thing. Second they ask how many grams of BaCO3 are formed if 100.0kJ are involved? I have no clue as to which mathematical formula I should use to determine this. Could someone please help me to understand this?

Rate expression for Reaction

I am having a real hard time with these problems. My professor is flying through these and not explaining them thoroughly enough for me to understand. I'm hoping you could help me with this. This is the question: The equation for the reaction between iodide and bromate in acidic solution is 6I-(aq) + BrO3-(aq) + 6H+(aq) ---> 3I2(aq) + Br-(aq) + 3H2O The rate of the reaction is followed by measuring the appearance of I2. The following data are obtained. [I-] [BrO3-] [H+] Initial Rate (mol/L x s) 0.0020 0.0080 0.020 8.89 x 10-5 0.0040 0.0080 0.020 ... click for more

reaction rate and tempersture

For the reaction: C2H4(g) + H2(g)----> C2H6(g) the activation energy is 181kJ/mol. The rate constant at 1000 degrees celsius is 1.6 x 10^3 L/mol/s. A.) at what temperature is the rate constant half its value at 1000 degrees Celsius? B.) What is the rate constant at 725 degrees Celsius? I was given this as a homework problem that I had wrong on a test and the teacher never went over it. I am confused on how to do it and I would like to see the proper equations and steps involved to obtain the correct answer.

write equation

esterification, write equation to show formation of ethyl formate