CEM 142 Exam 1 Questions Answered Correctly Graded A+

CEM 142 Exam 1 Questions Answered Correctly Graded A+ Open system - Answers mass/matter as well as energy can flow in and out of the system closed system - Answers mass/matter can not flow into the system but energy can flow in and out of the system isolated system - Answers nothing can enter or leave the system what is the difference between state and path function - Answers State function depend only on the initial and final states but not the path taken while a path function requires multiple steps and proofs to get to the final state what does delta H stand for - Answers thermal energy in a system endothermic reaction - Answers energy entering the system exothermic reaction - Answers energy leaving the system when bonds are being formed - Answers energy is released when bonds are being broken - Answers energy is required entropy - Answers measure of possible arrangements 2nd law of thermodynamics - Answers for any change in total energy there much be an increase in entropy what unit is used to show entropy - Answers delta S what happens to delta S as you increase more molecules - Answers it increases why does energy move from hot to cold - Answers because once energy is transferred to equilibrium. there are more possible arrangements what state has the most distinguishable arrangements - Answers gas because there are no interactions and its random what has a higher entropy? water freezing or ice melting - Answers ice melting because there are more possible arrangements due to more molecules and less interactions does entropy have to increase in the system a process to exist - Answers no, it just has to occur in that universe. either system or surroundings how do you calculate Snet total - Answers Ssytem + Ssurroundings what has the highest Hvap - Answers the molecules with more hydrogen bonds because more energy is need to overcome the IMF's what is the relationship between delta H and T - Answers entropy= thermal energy/temperature Gibbs free energy equation - Answers ΔG = ΔH - TΔS will this process occur exothermic (-) and entropy (+) - Answers yes, G will be negative will this process occur endothermic (+) and entropy (-) - Answers no, G will be positive will this process occur endothermic (+) and entropy (+) - Answers depends on T... why do we use Gibbs free energy - Answers because it is impossible to record the entropy of the entire universe. therefore Gibbs uses terms to reference the system how do you make a system more thermodynamically favorable - Answers cool it down because you want S and T to be smaller equilibrium - Answers reaction or process goes forward and back at the same rate what is an example of a molecule being at equilbrium - Answers water at 100.. it has not completed the phase change therefore not can be observed because it is stuck combustion reaction in terms of gibbs free energy - Answers -heat is given off (-) -number of arrangements increases because moving to gaseous state -most times always favorable what happens to the entropy when an exothermic reaction occurs - Answers + because more arrangements will occur what happens to the entropy when an endothermic reaction occurs - Answers - because bonds are being formed and less arrangements will occur what is 1 PPM equivalent to? - Answers 1 mg/L what is 1 PPB equivalent to? - Answers 1 ug/L