Chapter 9 Flashcards
(15 cards)
CHEMICAL EQUATION
During a chemical reaction, atoms are rearranged to create one or more new compounds
REACTANTS
Reacting substances
Reactants ——-> products
PRODUCTS
Newly formed substances
REACTANTS ——> products
COEFFICENTS
Denote the number of each type of atom or molecule present
Shown before the compound
In balancing, only the coefficients can be changed. “Don’t mess with the subscripts”
LAW OF MASS CONSERVATION
States that matter is neither created nor destroyed during a chemical reaction.
The atoms present at the beginning of a reaction are merely rearranged.
No atoms are lost or gained during any reaction, therefore the chemical equation must be balanced.
ATOMIC MASSES
Given on the periodic table
Different atoms and molecules have different masses, there are different numbers of them in a sample of the same mass
What changes during a chemical reaction?
Once a reaction is complete, there may be either a net release or a net absorption of energy.
EXOTHERMIC
Reactions in which there is a net release of energy
ENDOTHERMIC
Reactions in which there is a net absorption of energy
BOND ENERGY
The amount of energy required to pull two bonded atoms apart is the same as the amount released when they are brought together.
THERMODYNAMICS
Movement of heat
Why are exothermic reactions self-sustaining?
Energy tends to disperse which is one of the main driving forces of chemical and physical changes
ENTROPY
Is a measure of natural spreading energy…
Wherever there is spreading of energy, there is a corresponding increase in entropy
REACTION RATE
How the speed of a reaction depends on the concentration and temperature of reacting molecules.
Speed of any reaction
Reactant molecules must PHYSICALLY come together
CATALYST
Any substance that increases the rate of a chemical reaction without itself being consumed
