chap 10

Question 1

first law thermodynamics

Answer 1

energy cannot be created or destroyed but can be converted from one form to another w/o any loss

Question 2

define state function

Answer 2

describes equilibrium stare. chnage btwn 2 equil states is same regardless of path taken btwn them

Question 3

define enthalpy

Answer 3

total heat content of a system at constant pressure

Question 4

define Hrxn

Answer 4

change in heat energy per mole of rxn(state function)

Question 5

define exothermic

Answer 5

thermal energy is given off by the system to the surroundings (-)

Question 6

define endothermic

Answer 6

thermal energy is absorbed by the system from the surroundings (+)

Question 7

define specific heat capacity(Cp)

Answer 7

energy required to change one gram of substance by one degree. specific per gram. molar per mol.

Question 8

how much energy required to raise 50 g H2O by 5 C

Answer 8

q=(50)(4.18)(+5) = 1045J
Hrxn= 1045/2.77= 375.89 J/mol
0.376 kJ/mol

Question 9

define calorimeter

Answer 9

vessel of known heat capacity measures energy absorbed/release from rxn

Question 10

define hess’s law

Answer 10

enthalpy of rxn(Hrxn) for multistep process is equal to sum of Hrxn for constituent rxns (law of constant hear of summation)