1 Bell Ringer Active on SOCRATIVE (room:crice) OR Grab a paper copy! Turn it in to the tray and look over the Lab Procedure and today’s notes.

2 Chemical Reactions & Balancing Equations

3 Chemical Reactions 2 Parts : Reactants: substances at the start Products: substances at the end l The reactants turn into the products. Reactants  Products

4 Equation Format: “+” means “reacts with” or “and” “  ” means “yields” or “forms” Reactants written on LEFT side Products written on RIGHT side

5 Inquiry Lab l Effervescent Tablet –Na(HCO 3 ) & C 6 H 8 O 7 NaHCO 3 + C 6 H 8 O 7  Na 3 C 6 H 8 O 7 + H 2 O + CO 2 sodium + citric  sodium + water + carbon bicarbonate acid citrate dioxide

6 In a Chemical Reaction l The way atoms are joined is changed l Atoms are neither created nor destroyed. –This is the Law of Conservation of Matter l Balanced Equation: –Each element has same # of atoms on both sides of the equation.

7 C + O 2  CO 2 l This equation is already balanced –same number of atoms of each type of element on each side l What if it isn’t balanced already? C +  O O C O O

8 C + O 2  CO C +  O C O O This is called a skeletal reaction Shows all the reactants and products Does not show balanced quantities If it is NOT Balanced Already…

9 Cooking Analogy for Chemical Reactions: l Skeletal reaction: –Ingredients & description of meal l Balanced reaction: –Exact recipe

10 C + O  C O O O C Add molecules until there is an equal number of atoms on both sides. Use only molecules or atoms already in the formulas No new compounds used or created Start with the element you need more of! Skeletal Reaction  Balanced Equation

11 C + O  C O O O C 1C O 2 2C & 2O The 2 subscript on Oxygen means there are 2 of them in the molecule. Still not balanced  need 1 more C on the reactant side. Skeletal Reaction  Balanced Equation

12 C + O  C O O O C C 2C O 2  2C & 2O Equation: 2C + O 2  2CO

13 C + O  C O O O C C 2C + O 2  2CO Coefficient: Large Number left of the compound formula. Represents the number of molecules/atoms Helps to balance the equations makes # of atoms on left side = # on right side

14 2C + 2O 2  2CO 2 2C 4O 2C & 4O Notice the subscript only applies to the element it is next to! Coefficients & Subscripts on the same molecule The numbers must be multiplied to determine the number of atoms of that element.