Chemistry Unit 2

Indications of a Chemical Reaction

1. evolution as heat & or light

2.  production of a gas

3. Formation of a precipitate (solid produced as a result of a CR in solution that separated from a solution) 

4. Color change 

5. Sound 

Law of conservation of Mass

atoms can neither be created nor destroyed

Synthesis

combine 2 substances into 1

Decomposition

1 thing breaks into more substances

Single Replacement

an atom trades places with 1 part of a molecule in order to change they have to have the same charge

Double replacement

2 compounds switch places Balance :

1. Switch pos with neg first

2. Change to fit charges

3. Balance regularly

Combustion

Carbon Compound + O2 —> CO2+H2O

CxHy+O2→CO2+H2O

Diatomic Molecules

H,N,O,Br,I,CL,F (Brincl-Hof) or (I Have No Class On Friday Bro)

Collision Theory

to have a reaction particles must collide & they have to be energetic + be in the correct orientation

Activation Energy

Minimum amount of extra energy required to for the reaction to happen

Reaction Rate

Change in the concentration of reactants as time goes by

Chemical Equilibrium

state where forward reaction = backwards reaction

Le Chatelier’s

stress effects equilibrium) incl Concentration, Pressure & Temp

Concentration A+B=C+D

add more→making more products →products →right

take away →use products to replace missing →making more reactants →left

Pressure based on mol’s on either side

Inc pressure (dec vol) →less space →go to less GAS mol’s to fit in smaller space

dec pressure (inc vol) →have more space→go to more GAS mol’s to fill up the space

Temperature 2 types Endo Exo

Temp under Chat Endothermic Heat+A=B

• inc tmep is adding heat so shift right (bc it wants to cool down)

• dec temp is removing heat so shift left (bc it wants to warm up)

  products being lower (means you RELEASE energy) EXO

Temp under Chat Exothermic A=B+Heat

• inc temp : left to get cooler

• dec temp : right to get warmer

products being higher (means you ABSORB energy) ENDO

Which states of matter do not affect equilibrium?

pure solids & liquids

Three conditions for a reaction to be completed? (no =)

solid forms, gas forms and escapes, Ionic bonds form