Chemical Reactions
Two or more substances combine to form another substance.
2 H2 + O2 → 2 H2O
Synthesis Reaction
__HgO→ ___ Hg + ___ O2
2 HgO→ 2 Hg + 1 O2
In these reactions, when thermal energy is absorbed
endothermic reactions
a change in which one or more substances are converted into new substances.
Chemical Reactions
A(n) ____ chemical equation has the same number of atoms of each element on each side of the equation.
Balanced Chemical Equation
One substance breaks down, or decomposes, into 2 or more substances.
2 H2O → 2 H2 + O2
Decomposition Reaction
__ Al2O3 → __ Al + __ O2
2 Al2O3 → 4 Al + 3 O2
Some reactions require more energy to break bonds than is released when new ones are formed.
MORE ENERGY→ less energy
endergonic reactions
Total mass of the products is always equal to the total mass of the reactants.
Conservation of Mass
The reaction of a glow stick gives off energy in the form of light, but does not give off any heat. Which of the following best describes the reaction that occurs in a glow stick.
Exergonic
The ion of one compound replaces an ion in another compound to form at least 2 new compounds.
Ba(NO3)2 + K2SO4 → BaSO4 + 2 KNO3
Double Displacement
__ Fe + __ Cl2 → __ FeCl3
2 Fe + 3 Cl2 → 2 FeCl3
In these reactions, less energy is required to break the original bonds than is released when new bonds form.
less energy→ MORE ENERGY
exergonic reactions
A substance that slows down a chemical reaction.
Inhibitors
The burning of wood in a campfire that produces energy in the form of heat and light would be an ____ reaction.
exergonic and exothermic
When one element replaces another in a compound.
Zn + 2 HCl→ ZnCl2+ 2 H2
Single Displacement Reaction
__ BaSO4 + __ C→ __ BaS + __ CO
1 BaSO4 + 4 C→ 1 BaS + 4 CO
When the energy given off by a reaction is primarily thermal energy, the reaction is called an exothermic reaction
Exothermic reaction
A substance that speeds up a chemical reaction without being permanently changed itself.
Catalysts
An instant cold pack (absorbs energy in the form of heat).
endergonic and endothermic
Occurs when a substance reacts with oxygen to produce energy in the form of heat and light.
Combustion Reaction
__ Li + __ H2O → __ LiOH + __ H2
2 Li + 2 H2O → 2 LiOH + 1 H2
Examples of this type of reaction include:
dynamite explosion, burning fossil fuels
Exothermic Reaction
the number of units of each substance taking part in a reaction.
Coefficients
Photosynthesis (absorbs energy in the form of light, but does not involve any heat).
Endergonic