Energetics Flashcards
What is enthalpy change?
heat energy transferred per mole of the substance in a reaction during a physical or chemical change
does breaking bonds release or absorb energy?
Breaking energy requires energy so it absorbs energy (endothermic)
does forming bonds release or absorb energy?
Forming bonds releases Energy in order for the atom to become more stable
What are standard conditions?
100 kPa and 298 K (25 degrees celsius)
How is energy released when bonds are formed?
Electrons move to lower energy levels resulting in the release of energy (exothermic)
What is the Maxwell-Boltzmann distribution curve?
It is a graph with a curve showing the total number of molecules of reactants and the distribution of amounts of energy that the molecules have
What is a factor that affect the curve in the Maxwell-Boltzmann distribution curve?
- Temperature
How does temperature affect the Maxwell-Boltzmann distribution curve?
It lowers the highest peak so it can reach (less molecules with probable energy) and increases its final height (more molecules with high energy)
What is the equation for energy (in enthalpy change context)?
q=mcΔt
What is the equation for enthalpy change?
energy/number of moles
meaning of enthalpy change of formation?
It is the enthalpy change when 1 mole of a substance formed from its element in their standard state and under standard conditions (289K and 1 atm)
meaning of enthalpy change of combustion?
It is the enthalpy change when 1 mole of a substance is completely burnt in oxygen in its standard state and under standard conditions (289K and 1 atm)
Products of Complete combustion
CO2 and H20
Why does the Maxwell-Boltzmann distribution curve not touch the x-axis?
Due to there being a small proportion of molecules with very high kinetic energy
Formula for Percentage Yield
Actual Yield/Theoritical yield times 100
