All about chemical reactions! Flashcards
WHen do chemical reactions occur?
when particles collide and are rearranged to form new particles
Why is there an energy change in chemical reactions?
When particles collide, their BONDS are rearranged, causing energy to be released or absorbed
Are physical changes (ie. state changes) a type of chemical change?
no but heat still absorbed or released
Chemical energy is:
• Stored in bonds between atoms and molecules which result from
o Attractions between protons and electrons within atoms
o Repulsions between nuclei
o Repulsions between electrons
o Vibrations and rotations around bonds.
Do all substances contain chemical energy?
Yes
Define: enthalpy (heat content)
sum of the chemical potential and kinetic energy in a substance (or simply, chemical energy). H
Define: enthalpy change (heat of reaction)
difference between the total enthalpy of the products and that of the reactants. (delta H)
Enthalpy change reaction?
delta H = H (products) - H(reactants)
Define: exothermic reaction
reaction that releases energy into its surroundings
Describe enthalpy (change) for exothermic reaction
Enthalpy of reactants higher than products. Delta H is less than 0
Define: exothermic reaction
reaction that absorbs energy from the surroundings.
Describe enthalpy (change) for endothermic reaction
Enthalpy of products is higher than that of reactants. Delta H is greater than 0
Define: activation energy
minimum energy required to break bonds of reactants so a reaction can proceed
Do you know what energy profile diagrams are
you better
