2014-01-19

Quiz 2 Hint

Quiz 2 has a heat capacity problem, and the heat capacity value given in the problem is in units of "joules per (mole Kelvin)". Remember, for heat capacity problems, we're looking at changes in temperature. Whether it's Celsius or Kelvin, the ΔT is the same because 1 degree C and 1 K are exactly the same size. You can use either, but make sure you're doing everything in the right order. A temperature that changes from 3.45°C to 12.71°C is changing by:
ΔT = 12.71°C - 3.45°C = 9.26°C
If you prefer Kelvin, convert BOTH individual temperatures to K, THEN subtract:
ΔT = 285.86K - 276.60K = 9.26K
Other questions, let me know...

2 comments:

  1. I have a question on quiz number seven. The question asks for the molarity of cis-1-propenol and gives the gram amount of the trans-1-propenol, the total volume of solution, and the equilibrium constant. So I found the molar concentration of the trans and then set up a formula to find out the cis concentration (constant=cis molarity/trans molarity). I plugged in the concentration for trans and the constant and solved for cis molarity. However, I got this question wrong... What am I doing wrong?

    ReplyDelete
  2. The concentration you found (using the mass of trans-1-propenol) is the INITIAL concentration of reactant. You need to find the EQUILIBRIUM concentration to use in the equilibrium constant expression. Set up a table, and you'll have to do a little more algebra to solve for "x".

    ReplyDelete