Physical - 1.4 Energetics Flashcards
What is calorimetry?
The process of measuring the amount of energy absorbed or released during a chemical reaction.
Define endothermic reaction
One that takes in energy from the surroundings so the temperature of the surrounding decreases. The energy needed to break existing bands is greater than the energy released from forming new bands.
Define exothermic reaction
One that transfers energy to the surroundings so the temperature of the surrounding increase. The energy released from forming new bands is greater than the energy needed to break existing bands.
Is enthalpy change positive or negative for an exothermic reaction?
Enthalpy change is negative for an exothermic reaction
Is enthalpy change positive or negative for an endothermic reaction?
Enthalpy change is positive for an endothermic reaction
What is the equation for enthalpy change?
ΔH = sum of ΔH products - sum of ΔH of reactants
Define enthalpy
The change in heat content at a constant pressure
Where are the product and reactant lines on an endothermic reaction profile located?
Product line is above reactant line
Where are the product and reactant lines on an exothermic reaction profile located?
Product line is below reactant line
Define activation energy
The minimum energy that particles must have to successfully collide and cause a reaction
Define standard enthalpy of reaction
The enthalpy change when substances react standard conditions in quantities given by the equation for the reaction
Define enthalpy of formation
The enthalpy change when one mole of a compound is formed from its constituent element with all reactants and products in their standard states and understand the conditions
Define enthalpy of combustion
The enthalpy change when one mole of substance reacts completely with oxygen to form carbon dioxide and water only
What is the equation for enthalpy change?
q = mcΔT
ΔH = q/n
What does Hess’s law state?
The enthalpy change of a reaction is independent of the route taken
