<p>Hey, can anyone help me study for my chem final? I have some questions, is it okay if I post them up so someone can help me with them? Thanks.</p>
<p>Go ahead, I'm good at Chem (got an A!).</p>
<p>im a high school senior but i took ap chem last year (and if this is intro chem) i can possibly help you (i was a beast lol)</p>
<p>Substance AHf (KJ/Mol)
S02(g) -297
s03(g) -396
SO2Cl2(g) -364
H2SO4(l) -814
H2O(l) -286</p>
<p>a. Compute the amount of heat (in KJ) evolved when 7.5 g of SO2 reacts according to the following equation. </p>
<p>SO2(g) + Cl2(g) --> SO2Cl2 (g)</p>
<p>b. What is the balanced chemical reaction corresponding to AHf =-364 KJ for SO2Cl2(g)? </p>
<p>Thanks a lot in advance!</p>
<p>a.) 1. Find moles of all substances from 7.5 g of SO2 (using molar mass)
2. Delta Enthalpy of Rxn= [(SO2Cl2)]-[(SO2+Cl2)] - so plug in the calculated moles here
3.) Do the calculations with numbers</p>
<p>a). The delta(H) of the reaction as calculated from the data provided is:</p>
<p>-364 - 0 - (-297) = -67 kJ/mol meaning 67 kJ of heat is released for every mole of SO2 consumed</p>
<p>Thus, using the molar mass of SO2 found online, the amount of heat evolved from 7.5g of SO2 is:</p>
<p>(7.5/64.07) * -67 = -7.84 kJ meaning 7.84 kJ of heat is evolved</p>
<p>b) Since the reaction in part A is already balanced, I'm assuming they want:</p>
<p>SO2(g) + Cl2(g) --> SO2Cl2 (g) delta(H) = -67 kJ/mol</p>
<p>Can't see any other way of balancing the reaction.</p>
<p>Feel free to check my math, I'm known to be a little careless at times.</p>
<p>Thanks a lot! I worked it all out and you're right that's what I got.</p>
<p>However for the balanced equation according the heat of formation reaction you want your compounds in elementary form. So it should be S + O2 + cl2 -> SO2CL2</p>
<p>Ah, my apologies, I misread the question. I had thought that they wanted you to balance the chemical reaction given, which threw me for a loop. </p>
<p>Yes, in that case you just use the elementary form of the elements (the forms whose AHf = 0) in the final compound as your starting reactants and balance the reaction from that.</p>
<p>If anyone is good that math, I sort of suck at these kind of problems:</p>
<p>Find two non-negative numbers whose sum is 6 and whose product is a maximum. </p>
<p>Help me with #5. </p>
<p>Thanks!</p>
<p>y = x * (6 - x)</p>
<p>This is a parabola with the open end down so it has a maximum. To find the maximum in a parabola, use the formula to find the axis of symmetry (method used in algebra courses). Since you are in a calculus class, you're probably expected to take the derivative of the right-hand-side and solve the equation with that expression set to 0.</p>