Enthalpy of Reaction Flashcards
(15 cards)
- When a mole of metal oxide decomposes, enthalpy change is positive. What does
it tell you about the reaction?
A. The reaction is exothermic.
B. The reaction is endothermic.
C. The reaction is hypothetical.
D. The reaction does not require energy.
B. The reaction is endothermic.
The heat of a given reaction is called the change in
A. energy
B. enthalpy
C. entropy
D. electricity
B. enthalpy
- How do you calculate the enthalpy of a reaction?
Α. ΔΗ = ΔΗproducts - AHreactants
Β. ΔG = ΔΗ -TΔS
C. AT = q / mC
D. E =mc2
Α. ΔΗ = ΔΗproducts - ΔHreactants
What do you need to consider when looking for enthalpy value of a certain substance?
A. color of the species
B. mass of the species
C. physical state of the species
D. concentration of the species
C. physical state of the species
Which of the equation below refers to the enthalpy of formation?
A. Na(g) - Na+(g) + e- (Change in H= -364 kJmol-1)
B. C2H5OH(1) + 302(g) -+ 2CO2(g) + 3H2O (1) (Change in H = - 1286 kJmol-1)
C. 2C(s) + 2H2(g)-> C2H4 (g) (Change in H = - 52.3 kJmol-1)
D. Na+(g) -> Na+(aq) (Change in H = - 364 kJmol-1)
C. 2C(s) + 2H2(g)-> C2H4 (g)
(Change in H = - 52.3 kJmol-1)
deals with the heat absorb or release during chemical reactions or processes.
Thermochemistry
A thermochemical reaction or
process that absorbs heat from
the surrounding
Endothermic
Photosynthesis
Endothermic
A thermochemical reaction that releases heat to the surrounding is exothermic.
Exothermic
The difference between the energy released by bond formation and the energy consumed by bond cleavage during a chemical reaction.
ENTHALPY
- Measuring the change in
enthalpy allows us to
determine whether a reaction
will require or release heat to
occur. - Change in enthalpy is used
to measure heat flow in
calorimetry. - Enthalpy is used to
calculate minimum power for
a compressor. - Enthalpy change occurs
during a change in the state
of matter.
Importance of Enthalpy
The enthalpy change that takes place when one mole of compound is formed from its elements. It is denoted by AHf.
Example: The heat of formation of ferrous sulfide from its elements
Heat of formation
The enthalpy change that takes place when one mole of compound is completely burnt in excess oxygen. It is denoted by AHc.
Example: The heat of combustion of methane
Heat of combustion
The enthalpy change that takes place when the equivalent of an acid is completely neutralized with the equivalent of base.
Example: The heat of neutralization of nitric acid and sodium hydroxide
Heat of neutralization
The enthalpy change that takes place when one mole of substance is dissolved in specified quantity of solvent in given temperature.
Example: The heat of dissolution of magnesium sulphate
Heat of Dissolution
