Writing Net Equations

Before we start with out net equations, we have to be able to identify its states.

Now, how do we do that??

WELL . . . 

u can use the table of Solubities, which was given by Ms Chen.

The anions can be found in the left hand column, the cation in the second column and then you can continue buy following its presense of absense to the word soluble or non-soluble.

if the result is soluble: then its aqueous

if the result is non soluble: then its solid

( Now were on the exciting part)

WRITING NET EQUATIONS!

FINALLY!

(woooh)

So, for starters there is only a net equation when you have a precipitation.

( keep that in mind)

Also, MAKE SURE ( when ur balancing) that aq ions that are the same on BOTH SIDES gets cancelled out.

Here are some practices.

( Like what Ms Chen once said  " Practice makes u better, but not PERFECT" )

so PRACTICE EVERYONE! (:

Fe(s) + 2AgNO₃(aq) ® 2Ag(s) + Fe(NO₃)₂(aq)

Net Ionic Equation: Fe(s) + 2Ag⁺(aq) ® 2Ag(s) + Fe²⁺(aq)

CaCO₃(s) + 2HCl(aq) ® CaCl₂(aq) + H₂O(l) + CO₂(g)

Net Ionic Equation: CaCO₃(s) + 2H⁺(aq) ® Ca²⁺(aq) + H₂O(l) + CO₂(g)

2Na3PO4 (aq) + Ca9NO3)2 (aq) -> 6NaNO3 (aq) + Ca3(PO4)2 (S)

Net equation: 3Ca 2+ (aq) + 2 PO4 3- (aq) -> Ca3(PO4)2 (s)

TFV = (TIME FOR VIDEOS!!!!!!!)

VIDEO #1

VIDEO # 2



VIDEO # 3

Enthalpy Calculation

Calculate how much energy you need or you will produce in a reaction or how much reactants you need to produce a certain amount of energy
  
Mole conversion is required in this lesson

Eg. Calculate the amount of energy released when 1.50 moles of Carbon is reacted to form the product in this reaction: 
           4 C + 6 H2 + O2 --> 2 C2H5OH + 470 KJ

Step 1.
Convert delta H in the form you need
remember a minus sign for exothermic reaction

-470 KJ     
4 mol of C

Step 2.
Put in the equation and reduce to the unit you want
calculate the answer correctly

1.50 mol of C x -   470 KJ         = - 176.25 KJ
                          4 mol of C

Step 3.
make sure you have the correct number of sig, fig.
don't forget the unit!

-176.25 KJ --> -176 KJ

A: 176 KJ of energy is released

Lab 5B

Types of Chemical Reactions
There are examples of Synthesis, decomposition, single replacement, and double replacement in this lab and from the results, we can figure out the chemical reactions.

Purpose of this lab:
To observe a variety of chemical reactions, to interpret and explan observations with balanced chemical equation, and to classify each reactions as one of the four main types.

There are 7 reactions

1. copper reacts with oxygen gas

• shiny, hard copper turns into multicoloured
• 2Cu + O2 -> 2CuO    
• it's Synthesis

2. shiny, silver nail is put in a  blue CuSo4 solution

• nail under the colution becomes copper and it's white 
• Fe + CuSo4 -> FeSo4 + Cu
• Single Replacement

3. buring blue crystal - CuSO4 ˙ 5H2O

• whitish grey colour appears on the outside
• CuSO4 ˙ 5H2O -> CuSo4 + H2O
• Decomposition

4. add water into the product of reaction3

• crystal turns blue again
• CuSo4 + H2O -> CuSO4 ˙ 5H2O
• Synthesis

5. putting CaCl2 solution and Na2CO3 together

• white precipitate settled under a layer of clear liquid as they are added together
• CaCl2 + Na2Co3 -> 2NaCl + CaCO3
• Double replacement

6. put solid zinc into HCl solution

• bubbles forming when zinc in the solution
• Zn + HCl -> ZnCl + H2
• Single replacement

7. observe H2O2

• tiny bubbles traveling toward surface
• H2O2 -> O2 +H2
• Decomposition

What did i learn??

In this lab, I learnt the differences between each types of reactions and able to identify each.  I can write the chemical equation for each reaction and balance them correctly

Endothermic and Exothermic Reactions

Last class we learnt about endothermic and exothermic reactions and how all chemistry reactions involve changes in energy. Here are some of the notes we took last class.

An exothermic reaction is when energy is released to its surroundings.
An endothermic reaction is when energy is absorbed.

Molecules are held together by chemistry bonds

• When energy is added, bonds are broken
• When energy is given off, bonds are created

- If it takes more energy to break a bond than it does to form one, then it's an endothermic reaction.
- If it takes less energy to break a bond than it does to form one, then it's an exothermic reaction.

Energy Diagrams
- We can chart potential energy of the chemicals as they change from reactants to products.
- Reactants start with a certain amount of energy, energy is added to start the reaction and then energy is released as the reaction proceeds.
- Relative amounts of energy determines if a reaction is endothermic or exothermic.

*Enthalpy, H, is the heat contained in the system.

Here are some vocabulary you should know before you can understand an energy diagram.
Energy of Reactants: Total potential energy of all reactants in the reaction
Energy of Products: Total potential energy of all products in the reaction
Activation Energy: The energy that must be added to get the reaction to progress
Delta H: The change in potential energy during the reaction. (Energy of products minus the energy of reactants)

*In this diagram substrate = energy of reactants

Energy in the Equation

- Energy absorption/release can be placed directly in the equation

- Exothermic reactions have the energy term on the right hand side of the equation and a negative delta H

- Endothermic reactions have the energy term on the left hand side of the equation and have a positive delta H

- Energy is represented as KJ in equations (kilojoules)

- Example: CH4 + 2O2 -> CO2 + 2H2O + 812KJ