WARM UP Law of Conservation of Mass 10/16/17 Coal is completely burned 100 g 100 g START END What do you observe? Write down your observations.

Law of Conservation of Mass Lavoisier (1743-1794) Coal is completely burned 100 g 100 g A: Mass of the jar & its contents remains the same. Mass is conserved. START END In a chemical reaction, matter is neither created nor destroyed, it is transformed into something else.

balanced mass Since matter can not be created or destroyed, chemical reactions must be __________ in terms of _________. balanced mass The amount of mass you start with must equal to the mass of the products: Mass of Reactants  Mass of Products 100g total = 100g total

The mass on both sides of the arrow must be equal. According to the law of conservation of mass, how much zinc was present in the zinc carbonate? + = + 256g 256g REMEMBER !!! The mass on both sides of the arrow must be equal. A 40 g B 88 g C 104 g D 256 g ANSWER: 256- 152 = 104g of Zn

10/17/17 WARM UP Quick Write: In your IAN Notebook, WRITE the Law of Conservation of Mass in your own words.

CuCO3(s)  CuO(s) + CO2(g) 123.6 g 79.6 g ? g 44.0 g According to the law of conservation of mass, how much carbon dioxide was present in the copper (II) carbonate? CuCO3(s)  CuO(s) + CO2(g) 123.6 g 79.6 g ? g + 44.0 g 123.6g 123.6g What are the reactants? CuCO3 123.6 g What is the mass of reactants? Mass? CuO & CO2 What are the products? What is the mass of products? 79.6 g + CO2 Answer: 123.6 – 79.6 = 44.0g of CO2

For the Previous Two Examples You can set every Chemical Equation up like an Algebraic Equation and solve it for the variable. For instance this equation, can be written algebraically using the masses given on the previous slide like below. Now you only have to solve for x! 123.6 [g] = 79.6 [g] + x Show the algebraic equation for your solutions to the previous 2 problems in your notes. CuCO3(s)  CuO(s) + CO2(g)

Solve the follow problem in your IAN Notebook. Practice #1 Solve the follow problem in your IAN Notebook. If 50 grams of sodium (Na) react with chlorine (Cl2) to form 125 grams of salt (NaCl), how many grams of chlorine reacted? 2Na + Cl2  2NaCl

Solve the follow problem in your IAN Notebook. Practice #2 Solve the follow problem in your IAN Notebook. From a laboratory process, a student collects 28.0 g of hydrogen (H2) and 224.0 g of oxygen (O2). How much water was originally involved in the process? H2O  H2 + O2