Unit 2 (Thermochemical Changes) Flashcards
What are four types of energy changes?
- Temperature change LOW
- motion - KE - Phase change
-bond energy - PE - Chemical changes
- rearranged atoms - Nuclear changes HIGH
- change in atoms, involves nucleus bonds
What is an open system?
Energy and matter can move to and from surroundings
What is a closed system?
Only energy can be transferred to and from surroundings
What is an Isolated system?
neither energy nor matter can be transferred to and from surroundings
How do systems and surroundings interact in an endothermic reaction?
Endothermic reactions absorb heat from surroundings, feels cold. So when the system temperature increases the surroundings decrease.
How do systems and surroundings interact in an exothermic reaction?
Exothermic reactions transfer heat to the surroundings, feels hot. So when the system temperature decreases the surroundings temperature increases.
What is a calorimeter, and how it determines energy changes?
Is a devices that determines the heat exchanged between a substance and a calorimeter. It determines the change through the temperature of the water - weather heat is gained or lost
What is specific heat capacity?
The quantity of energy required to raise the temperature of a unit mass of a substance by one degree celcious or one kelvin
Define enthalpy and what is the symbol and units?
Enthalpy is the total kinetic and potential energy within a system at constant pressure the symbol is delta H and the units are J or KJ
What happens to the enthalpy of an endothermic reaction?
More potential energy after the reaction as it is stored in the system. The system has more product less reactant. Enthalpy is positive
What happens to the enthalpy of an exothermic reaction?
Less potential energy after the reaction as all the energy is lost from the system. The system has less product more reactant. Enthalpy is negative.
