silently make an observation about the pictures above

Nov 17 / 18 Act B25 Conservation of Mass CH Q LEARNING TARGET: I can conduct an investigation to determine how the total mass of the reactants compares to the total mass of the products in a closed system. CH Q How does the total mass of the reactants compare to the total mass of the products in a chemical reaction? VOCAB: next slide

amount of reactants = amount of products Closed system conservation of mass Exothermic Mass open system Products reactants nothing in or out amount of reactants = amount of products reaction gives OFF heat "stuff" "things" can enter or leave chemicals after reaction chemicals going into reaction

What type of system is a person – open or closed? DISCUSSION Which system is a closed system and which is an open system? Explain what the means. OPEN: "things" can get in or get out CLOSED: "things" can NOT enter or leave What type of system is a person – open or closed? OPEN! (you drink, eat, breathe in and then breathe out, pee and poop – right??)

What happened to the mass? DISCUSSION -- Demo Predict: What do you think will happen to the mass of the system – the bottle and reactants – as the reaction occurs? Will it increase, decrease, or stay the same? 1 2 3 4 After Demo: What new evidence have you observed that indicates a chemical reaction occurred? What happened to the mass?

PROCEDURE AND DATA MATERIALS: PROCEDURE: Read on pg. B-65-66 and summarize DATA: WS 25.1 Mass of Reactants and Products (notes in Journal)

What trends do you see in the data? POST DISCUSSION What trends do you see in the data? What does this tell us about what is happening to the mass of the reactants as compared to the mass of the products? numbers before and after are similar 1 3 4 masses before reaction and after are similar

3. Was this an exothermic reaction? Explain! POST DISCUSSION 3. Was this an exothermic reaction? Explain! 1 2 4 YES! "exo" = "outside", "thermic" = "heat" (container felt warm after reaction)

4. What evidence have you observed that indicates a 4. What evidence have you observed that indicates a chemical reaction occurred? (looking for 3 things) properties changed – gasses formed – heat produced

Which of the following statements best defines the law of conservation of mass? Mass cannot be created but it can be destroyed under extreme pressure. Mass cannot be conserved during a chemical reaction; a little bit of mass is always lost The mass of a closed system cannot change over time; mass cannot be created nor destroyed When added to a system, energy can destroy mass.

 In a chemical reaction, 300 grams of reactant A are combined with 100 grams of reactant B. Both A and B react to completion. How much will the product weigh? 200g 400g 300g It cannot be determined

In a reaction, 25 grams of reactant AB breaks down into 10 grams of product A and an unknown amount of product B. Using the law of conservation of mass, how much does product B weigh? 25g 10g 15g Cannot be determined

Magnesium + Oxygen ------> Magnesium Oxide REACTANT(S) PRODUCT(S) Magnesium + Oxygen ------> Magnesium Oxide 48.6 g + 32.0 g -----> 80.6 g (1) What is the mass of each reactant? What is the mass of the product? What is the total mass of reactants? Does this experimental data support the Law of Conservation of Mass? Explain.

Explain in detail what is happening in this diagram Explain in detail what is happening in this diagram! Might be helpful to draw the diagram in your notes.

ANALYSIS - Discuss and answer Q 1 & 3 on pg. B- 67 ANS CHALLENGE Q How does the total mass of the reactants compare to the total mass of the products in a chemical reaction? A: HOMEWORK 1. TURN IN YOUR JOUNRAL!!!!!!