Mod 6 - EBs with rxns Flashcards
T/F: If Delta(H_hat) is -ve, then rxn is endothermic
FALSE: rxn is exothermic. E removed from reactor to keep temp from increasing
T/F: If Delta(H_hat) is +ve, then rxn is endothermic
TRUE: E added to reactor to keep temp from decreasing
T/F: Typically, reactors can handle the E changes occurring in the system without requiring substantial heating or cooling to maintain steady state.
FALSE
T/F: To calculate the change in enthalpy that occurs due to a chemical rxn, specific heats of rxn must be combined with extent of rxn.
TRUE
T/F: Specific heat of rxn is the enthalpy change for a process in which stoichiometric quantities or reactants react completely to form products at const. T&P
TRUE
T/F: St. heat of rxn is specified for reactants and products at st. T&P cond’t
TRUE
T/F: A calorimeter measures the heat of rxn equivalent to digesting a meal in the human intestinal tract.
FALSE
T/F: Heats of rxn may be measured in a calorimeter. which is a closed reactor submersed in a fluid and enclosed in an insulated vessel, and where the increase or decrease in fluid temp determines the amount of E released or absorbed during a rxn.
TRUE
T/F: The calorimeter can be used to estimate the heat of rxn to form CO from solid C and diatomic O2
FALSE
T/F: Hess’s Law says that math can be applied to estimate heats of form.
FALSE: algebra can be applied to estimate heats of reaction, but not heats of form if they’re not equivalent
T/F: At low/moderate pressure, deltaH(hat)r is nearly independent of pressure. (deltaH(hat)r(T,P) = deltaH(hat)r(T))
TRUE
T/F: Heats of combustion table has values listed for the complete formation of the substance
FALSE: Heats of reaction does, which is why we include extent of reaction - deltaH(dot) = extent(dot)*deltaH(hat)r
T/F: Value of heat of rxn depends on phase of the reactants, but not the products.
TRUE: depends on phase of both!
T/F: There is no difference between deltaH(hat)(T,P) and deltaH(hat)º
FALSE: Superscript “ º “ means heat of rxn is at standard temp and press cond’t (25ºC and 1atm), which means the amount of heat that must be added/removed to keep @ these cond’t
T/F: The standard heat of reaction is preferred when all elements are in st. cond’t (25ºC and 1atm)
FALSE: you can use either method but standard heat of FORMATION is generally more efficient when the reagents are in st. cond’t of 25ºC and 1 atm (B.1)
T/F: st. heat of combustion = enthalpy associated with the complete combustion of one mole of substance at 25ºC and 1 atm
TRUE
T/F: The st. heat of combustion will always be the opposite sign and value to the st. heat of formation (hint: look at B.1)
FALSE: same sign, but not same value
T/F: It is not necessary to draw a PFD in your solution or define your reference states
FALSE: Although PFD not necessary, clearly defining reference states ARE necessary
T/F: Heats of reaction is a more direct method of obtaining the enthalpy of the entire reaction (moving horizontally through the reaction equation) while heats of formation looks at the enthalpy associated with each component in the system
TRUE: Enthalpy of formation looks at the enthalpy of reaction for each component of the system (branching off the beaten path, sort of looks like a family tree or a wack-ass pyramid scheme)
T/F: Dealing with a single reaction for which deltaH(hat)rº is known = heat of form more preferred
FALSE: heat of rxn more preferred (can be calculated through Hess or
T/F: The heat of formation method is ideal for multiple reactions or for single reactions for which deltaH(hat)rº is unknown
TRUE
T/F: For heats of form, the reference state is that of all elements constituting the reactants and products at 25ºC and 1 atm
TRUE
