Chapter 8 Flashcards
A chemical reaction occurs when there is a?
change in chemical composition in one or more substance
chemical reactions takes place where?
microscopic level but the results of chemical reaction are observable by naked eyes
results of chemical reaction observable by our naked eye
a. a precipitate is formed or dissolved
b. a change of color
c. effervescence occurs (gas formation)
d. energy in the form of heat, light, or electricity is released
what happens in a chemical reaction?
change occurs in a chemical reaction:
- chemical composition
- the ways atoms are hooked up together
- old bonds are broken and new bonds are formed
writing chemical equations
Reactants ---> products arrow = indicate change \+ = and, reacts with, combines with --> = to produce, to give, to geenrate (triangle) = reaction conditions
law of conservation of mass
- matter cannot be created or destroyed in a chemical reaction
- atoms are not gained or lost during chemical reaction
- must be same number of each type of atom on both side
- chemical equation must be balanced
the physical states of the reactants/products
gas, liquid, solid, aqueous
coefficient
the molecule “ratio” in reaction
the diatomic molecules
- H2 O2 N2 Cl2 Br2 I2 F2
the coefficients in a chemical equations tells us ?
how many moles of each reactants are required to produce a certain number of moles of products
law of conservation of mass:
the total mass of reactants used= the total mass of products produced
exothermic reaction
energy is released as the reaction occurs
hill
endothermic reaction
requires the input of energy as the reaction occurs
mountain
catalysts
lower the activation energy for chemical reactions
- reactions proceed more rapidly with the lowered activation energy
when the speeds of the forward and reverse reactions are the same, the amount of reactants and products stay constant. the reversible reaction is said to reach?
chemical equilibrium
le chateliers principle on chemical equilibrium
- any change (called stress) to an equilibrium condition upsets the equilibrium of the system
- there will be a change in the rate of the forward or reverse reaction to return the system to a new state of equilibrium
- system shifts to new state of equilibrium that relieves the stress applied
if a reactant or a product is added to the system the equilibrium is shifted in what direction?
in the direction that consumes the added reactant or product
if a reactant or a product is removed from the system, the equilibrium is shifted in?
the direction that increases the removed reactant or product
result of adding catalysts to the position of equilibrium
no change
Oxidation
- always involves Loss of Electrons (Leo)
- may involve gain of oxygen and loss of hydrogen
reduction
- always involves Gain of electrons GER
- may involve loss of oxygen and gain of hydrogen
Oxidation - reduction happens?
simultaneously
total # of e loss = total # of electron gain
combination reaction
two or more elements (or simple compounds) combine to form one product
decomposition reaction
one substance splits into two or more simpler substances
