Anyone know how to solve thermochemistry problems???
350981
This isn't too bad.\n\nFirst, find the enthalpy of formation for each of the reactants and products.\n\nFe2O3(cr) = -272 kJ/mol\nCO(g) = -110.525 kJ/mol\nCO2(g) = -393.509 kJ/mol\nFe = 0 kJ/mol\n\nThen add the enthalpies of formation for the reactants and subtract the enthalpies of formation for the products:\n\nFe2O3 + 3CO - (3CO2 + 2Fe)\n\n-272 kJ/mol + 3(-110.525 kJ/mol) - 3(-393.509 kJ/mol) - 2(0) = -603.575 kJ/mol - -1180.53 = -576.952 kJ/mol \n\nThat should do it.
863469
I think it's math! I've had trouble with it =) maybe chemistry also
678334
This is a bit complicated but you might try this....\n\nStart with a centralized heat source, preferably electrical, so it should remain fairly constant.  You will need three thermometers, each to be held in place by their own stands.  Place a block or bar of metal so that it does not quite touch the heat source, and in contact with its thermometer at the far end.  Place a wooden bowl with water (a metal or glass container would taint your study ) near the heat source with its thermometer just in the water.  Place your last thermometer the same distance from the heat source, thus testing the heat conductivity of air.  If you had access to more thermometers and stands, you could place them at various points in a line from the heat source.  You will notice that the last thermometer will by far have the lowest readings.
811304
let thetemperature of the mix be 't'*Cfind the heat lost by coffee\nfind the heat gained by ice in three stages\na)from -2.2*C to 0*C\nb)for melting and becoming water at 0*C\nc)for getting to the equilibrium temperature of the mixture\nequate and solve
934498
This is a three step problem.  Since you're losing heat temp is going down.  First calculate the amount of heat needed to go from 25.0 C to 0.00 C.\n\nq1 =  1 g X 4.18 J/gC X -25 = -104.5 J\n\nNow you have water at 0 C which needs to freeze.  You need to remove the heat of fusion to make ice.  deltaHf is -335.5 J/g.\n\nSo q = m X deltaHf = 1.0 g X 335.5 J/g = -335.5 J.\n\nNow we've used up 440 J so far, and the remaining 24 J will lower the temperature of our 1.0 gram of ice.\n\nThe heat capacity of ice is 2.1 J/gC and we'll need to solve for delta T.\n\n-24 J = 1.0 g X 2.1 J/gC X delta T\n\ndelta T = -24 J/ 2.1 JC= -11.4 C.\n\nSo the final state and temperature would be ice at - 11.4 C.\n\nSo the answer of -12 C should be correct with more care paid to significant figures and proper rounding.
689186
I think that this site will solve all your problems:\n\nhttp://www.jsftutorials.net/
861843
Start with the Ca then balance the number of PO4 ions, then balance the Oxygen and the hydrogens should balance themselves out.  Its just trial and error. Monkey with it until it works.
485893
Check on the internet for the ratios used by comercial factories, then prepare a solution from glycol and water in the given proportion. That's all!!!
655398
Here's how to solve it (I am convinced that you should do your own homework, but hints are OK as long as you learn something):\n\nStart solving by finding the molecular mass of the compound.\nA. Volume occupied by one mol of gas is 22.4 L at standard temperature and pressure (STP: 760 mmHg and 273 K (0 C))\nTo find the volume of gas that weighs 2.57 g at STP, use formula: P1V1/T1=P2V2/T2, where R is 0.08206, P1=319 mmHg, V1=2 L, T1=298 K; P2=760 mmHg, T2=273 K and V2 is unknown (it will be somewhat less than 1 L).\nAfter you get this volume, see how many mols do you have in it: divide 22.4 by V2 you just got. Then multiply this number by 2.57 and get the molecular mass of your compound (M(X)).\n\n2. Multipy M(X) separately by 0.6481, 0.136 and 0.2159 to get number of atomic weight units that are allocated to C, H, and O respectively. \nThen divide first number by 12, 2nd by 1 and 3rd by 16 to see how many atoms it amounts to. The resulting integer numbers are X, Y, Z.\n\n3. CxHyOz is the empirical formula of your compound. Google it to get the possible molecular ones. This is a trick question, so there will be more than one but less than 8. All of them are alcohols or ethers.
53189
http://tigger.uic.edu/~mansoori/Thermodynamic.Data.and.Property_html\nhttp://www.aii-usa.com/proezgc/database.htm\nhttp://theweatherprediction.com/thermo/images/\nhttp://www.lib.utexas.edu/chem/info/thermo.html
949133
OMG!\ni have the same question!\nmine is:\nA piece of an unknown metal has a mass of 20.0 g and at 100.0 C is placed in a styrofoam cup calorimeter containing 50.7 g of water at 22 C. If the final temp is 27.2 C, calculate the specific heat capacity of the metal. Assume that all the energy lost by the metal is gained by the water.\n\nok, haha fine, not the SAME question, but close enough. But, i'm uber confused. ><
988889
understanding the reaction meachanism \neffect of catalysts etc....\ndetermining the amounts needed
624146
check brilliant tutorials homepage...they have posted the solutions...by the way was there a set A  as well?? anyways good luck!
1024879
I have the same problem with my electric stove.  Overtime, (just like everything) they got worn out and what my neighbor did was replace the entire unit...thus giving her an excuse to remodel the ktichen.  However that is WAY too expensive...Is it that every plate does not heat up as much as it used to?  Now my family's remedy is to use the plates that we hardly used before (the ones in the back for example).  I haven't taken any courses in engineering but I would love to explain why if I had :(  I agree with the previous post, call a professional in electrical appliances.
697545
1- find heat quantity\n Q=C*t\nQ = heat quantity of the reaction\nC= heat capacipy of calorimeter\nt=temperature increasing\n\n2- find heat of reaction \n H=(Q*1000)/(N*V)\nN = normality of acid and base\nV= volume of acid and base
17656
Best technique is to look for where it is unbalanced and change it so it is balanced. Repeat until it is balanced.\n\neg. We need 2 hydrogen here on the left, so go for:\n\nMg + 2HCl -> MgCl + H2\n\nNow we need another 2 as we have 2 Cl on the left and one of the right.\n\nMg + 2HCl -> 2MgCl + H2\n\nNow we need to have 2 Mg on the left as we have 2 Mg on the right. So we get:\n\n2Mg + 2HCl -> 2MgCl + H2\n\nAll balanced so that is the answer.
106704
If you go to a search engine, like google, you can just type in "balancing chemical equations" and it will give you tons of info. We were doing this in chemistry a few weeks ago, and thats how I found alot of help online. \n\nGood luck!!