2. Is this balanced or not? 2 LiCl + Br 2 2 LiBr + Cl 2 3. Summarize notes from last assignment.

Transcription

1 Assignment #3 Temperature in Reactions LO: To recognize how to tell if a chemical reaction has occurred. EQ: Compare and contrast endothermic and exothermic reactions. Give examples of each. AGENDA 1. Discussion 2. video HOMEWORK 1. Finish Worksheet LEVEL ZERO VOICE Catalyst (10 minutes, individual work): 1. Is it a physical or chemical change? Why? Glass breaking Burn book Make lemonade Cook waffle Staple paper 2. Is this balanced or not? 2 LiCl + Br 2 2 LiBr + Cl 2 3. Summarize notes from last assignment.

2 Chemical Equations: Equations that show reactants and products in a chemical reaction Reactant: starting materials (left side of equation) Products: the new substance(s) formed (right side)

3 tin + oxygen gas tin oxide (reactants) (product) 2 Sn + O2 2 SnO (reactants) (product)

4 2H2O 2H2 + O2 Coefficient: how many molecules or atoms (comes before the atom or molecule) Subscript: the little number in a chemical formula that tells how many atoms of an element are in a molecule

5 Law of Conservation of Mass: the total mass before a chemical reaction is the same as the total mass after the reaction In a chemical reaction, atoms are REARRANGED, not destroyed In all chemical reactions, the amount of matter is the same before and after the change takes place No atoms are lost, no atoms are gained

6 Balance a Chemical Equation When you are writing a chemical equation: 1. Make sure the symbols and formulas for the reactants and products are correct 2. Check to make sure both sides are balanced (same number of each atom appears on each side of the equation reactants and products) - compare the number of one atom on both sides of the arrow to make sure it s the same on both sides

7 Parentheses in Chemical Equations When you count atoms inside a parentheses, the subscript following the parentheses multiplies all the atoms inside. Ca (OH) 2 Count the atoms: 1 Ca atoms 2 O atoms 2H atoms

8 Parentheses in Chemical Equations When you count atoms inside a parentheses, the subscript following the parentheses multiplies all the atoms inside. Ca (OH) 2 Count the atoms: 1 Ca atoms 2 O atoms 2H atoms

9 Quickwrite: How do you know when a chemical reaction has taken place?

10 Quickwrite: How do you know when a chemical reaction has taken place?

11 Observations: detailed observations (no more than two lines)

12 Cl.Ev.Re.: Prove whether the reaction you witnessed was a chemical or a physical change. Claim: Write your claim. (Was it a chem rxn?) Evidence: What is your evidence to support your claim? State evidence without reasoning. List lines of evidence. Reasoning: Explain why your evidence supports your claim.

13 What do you think these words mean? Exothermic Endothermic

14 Let s break it down Exo Endo - Thermo -

15 So what do you guys think endothermic means? What do you think exothermic means?

16 Video:

17 In your glossary write: Endo: absorbing, within Exo: outwards Thermo: heat

18 In your NOTES write: Exothermic reaction heat is released The actual particles are losing heat to the surrounding Surroundings feel warmer

19 In your NOTES write: Endothermic reaction heat is absorbed The actual particles are gaining heat Surroundings feel cooler because it is losing heat

20 Assignment #3 Temperature in Reactions LO: To recognize how to tell if a chemical reaction has occurred. EQ: Compare and contrast endothermic and exothermic reactions. Give examples of each. AGENDA 1. Discussion 2. Exploration HOMEWORK 1. Finish Worksheet LEVEL ZERO VOICE PROCESSING TASK (10 minutes, individual work): 8 flips Exothermic (define) Energy is. (released/absorbed) Heat is. (gained/lost) Feels. (warm/cold) Endothermic (define) Energy is. (released/absorbed) Heat is. (gained/lost) Feels. (warm/cold)