Cut out the table and glue it onto page 48. Warm-Up 4/14/14 Cut out the table and glue it onto page 48.

Balancing Equations Monday 4/14/14

Conservation of Mass Chemical equations must follow the “Law of Conservation of Mass”= mass can neither be created nor destroyed in an ordinary chemical or physical process. What you start with must show up in the end; atoms are just rearranged.

Good 2 slices of bread + peanut butter + jelly → PBJ 4 legs + seat → a chair 1C + O2 → 1 CO2

What is wrong with these? lettuce + tomato + cheese → pizza Mg + Cl2 → NaCl 2Mg + Cl2 → MgCl2

Balancing Equations In order to follow the Law of Conservation, we need to make “Balanced Equations” each side of the chemical equation has the same number of each type of element.

Do’s and Don’ts DO balance equations by adding coefficients in front of reactants and products. You DO NOT change subscripts!!

Final Balanced Equation Examples Given Equation Starting Reactants Starting Products Final Reactants Final Products Final Balanced Equation H2 + O2 → H2O Na + O2 → Na2O

When Done: Analysis (pg.48) What does the arrow mean? What side of the equation are the reactants found? Products? The Law of Conservation says the matter cannot be created or destroyed. How does this relate to balancing equations? Why can’t you change the subscripts?

Basic Procedure Write down the equation, count the # of each type of element on both sides of the arrow. Place coefficients in front of the chemical cards to multiply the # of each element until they are the SAME on both sides. Record the final counts of both reactants and products, then record what the final equation looks like!