The specific internal energy of formaldehyde (HCHO) vapor at 1 atm and moderate temperatures is given by the formula O(J/mol) = 25.96T + O.02134T2 where T is in 0e. (a) Calculate the specific internal energies of formaldehyde vapor at OC and lOOe. What reference temperature was used to generate the given expression for U? 410 Chapter 8 Balances on Nonreactive Processes (b) The value of 0 calculated for 100C is not the true value of the specific internal energy of formaldehyde vapor at this condition. Why not? (Hint: Refer back to Section 7.5a.) Briefly state the physical significance of the calculated quantity. (c) Use the closed system energy balance equation to calculate the heat (J) required to raise the temperature of 3.0 mol HCHO at constant volume from OC to 100C. List all of your assumptions. (d) From the definition of heat capacity at constant volume, derive a formula for Cv(T)[J/molC). Then use this formula and Equation 8.3-6 to calculate the heat (1) required to raise the temperature of 3.0 mol of HCHO(v) at constant volume from OC to 100C. [You should get the same result you got in part (c).]
Enzymes • Enzymes are an example of globular proteins • They are biological catalysts that speed up reactions by lowering the activation energy • They are able to work under mild conditions of temperature and pH (~7) • They do not just randomly bind to things-‐ they’re very specific • They can be regulated by being turned on or off or turned up or down Enzymes DO NOT make things occur that weren’t going to happen anyway!
