Warm Up Complete this warm up. Be sure to include today’s date. Copy the following and complete the matching activity. 1___Physical Change a) atoms are not created or destroyed 2___Chemical Change b) A solid that forms from two liquids reacting 3___Reactive c) is formed as the result of a chemical reaction. 4___chemical Equation d) representation of a chemical reaction 5___ Subscript e) Cutting, melting…affects the form, but does not change identity 6___ Physical Property f) before the C. formula, number of molecules 7___Chemical Property g) digestion, rusting… change in identity 8___Reactant h) CO2, NH4, CaPO4 Shows number of atoms 9___Product i) shows proportion of atoms in a compound 10 ____ precipitate j) density, phase… measureable and /or observable 11 ____ Coefficients k) How likely to undergo a chemical reaction 12 ____ Law of conser. l) Can’t be observed without changing of Matter/Mass the identity 13 ____ Chemical Formula m) present at the beginning of a chemical reaction E G K D H J L M C B F A I

Warm Up Sit in your group of four from yesterday. You will need your notebook, glue stick and Chromebook today. Do not open your Chromebook until I instruct you to. .so, Thinking back on the lab from yesterday, I want you as a group to decide if the Gak was created as a result of a chemical change or physical change. On your sheet write three reasons to support your answer. (remember key indicators)

Evidence of a Chemical Change Can not be reversed Changes chemical properties Formation of gas Formation of precipitate (a solid that results from two liquids reacting) Change in color Change in odor Change in energy Endothermic Absorbs heat energy (gets cold) Exothermic Releases heat energy (gets hot)

Chemical Reaction chemical reaction, one or more substances change into one or more new substances because the atoms are rearranging into different products with different properties. Glue, Borax, water reacted to created GAK (Polymer…like in plastic) Gak has very different properties from the reactants.

Academic Conversation: What do you know? 1. Get with a partner 2. Copy the sample work below. 3. With your partner write as much information as you can about what you notice. 3 Ag2S + 2 Al 6 Ag + Al2S3

What do you know? 3 Ag2S + 2 Al 6 Ag + Al2S3

Group Work Read pages 33-34 in Coachbook. Popcorn read in with your partner Add more detail to your equation

3 Ag2S + 2 Al 6 Ag + Al2S3 + + What do you see? Does this remind you of anything in math? Chemical Equation 3 Ag2S + 2 Al 6 Ag + Al2S3 Reactants Products What does the subscripts and coefficient tell us? coefficients subscripts + + 6 Ag 3 2 Al Ag Al 2 Al Ag Ag 3 S 2 Al Ag 6 Ag 6 Ag Ag 3 S Silver + sulfide Aluminum sulfide Aluminum creates Silver +

The Law of Conservation of Mass What do you notice? 3 Ag2S + 2 Al 6 Ag + Al2S3 6 Ag 6 Ag 3 S 2 Al 2 Al 3 S The amount of atoms of each element in the reactants are equal to the amount of the same in the product!!!! The Law of Conservation of Mass Matter (mass) can neither be created nor destroyed, but rearranged.

How do you know if an equation reflects The Law of Conservation of Mass? reactants  products 2H2 + O2  2H20 A chemical equation is balanced when it reflects the conservation of mass. Graphic: http://www.chemistry.ohio-state.edu/betha/nealChemBal/

Recap Chemical equation represents a chemical change. It identifies the starting and ending chemicals. The starting chemicals are called the _____ The ending chemicals are called the ______ reactants products.

What are Reactants & products Reactants – elements and/or compounds that undergoes a chemical change Products – elements and/or compounds that are the result of the chemical change/reaction yields reactants  products

Balancing Equations Subscripts – a small number used to represent the number of atoms in the preceding element. (can never change) Coefficient – the number that appears at the beginning of a molecule or element that indicates its amount (can be changed). Subscript Coefficient 2H2

Count the number of atoms 5 O2H3 = _____O ______H CO3 = _____ C ______ O 8 NaOH2 = _____ Na _____O _____H

Warm up Ex. a) NaCO3 = Na=1 b) 5 ZnSO4 Zn= 5 (5x1) C=1 S= 5 (5x1) 1.You will need your notebook, glue and Chromebook. 2.Do not open your Chromebook until I tell you to. 3. Take out homework Copy and then determine the number of atoms in each compound. Ex. a) NaCO3 = Na=1 b) 5 ZnSO4 Zn= 5 (5x1) C=1 S= 5 (5x1) O=3 O=20 (5X4) H2O 6) 2H2NCH3Br MgCl2 7) 4NaC2H3O2 Li2O 8) Li2SO4 3Al2O3 9) HBr 2CH3OH 10 CH4

User name: ridgeroadms Password: ravens Click Science Takeout Chromebooks Go to BrainPop log in User name: ridgeroadms Password: ravens Click Science Click Matter and Chemistry Watch Chemical equations Take Classic Quiz

The same number of each kind of atom must be on the left side of the arrow as are on the right side when an equation is balanced. Al O Al O Al O O Al O Al Al

This is now a balanced equation Balancing an equation: H2 + O2  H2O 2 2 H H H O H O O First: Count the atoms on both sides of the yield arrow Second: Determine which atoms are not equal and add coefficients to balance these atoms. 2 H atoms 2 H atoms 2 O atoms 1 O atom Hydogen atoms are = Hydogen atoms are = Hydogen atoms are ≠ 4 H atoms 2 O atoms 4 H atoms 2 O atoms Oxygen atoms are = Oxygen atoms are = Oxygen atoms are≠ When a coefficient is added you must multiply all atoms in the compound by this number. Redo the inventory After redoing the inventory, add coefficients to balanced other atoms. With each additional coefficient the inventory must be updated. Oxygen, as a product, must be multiplied by 2. A coefficient is placed in front of the compounds that contains O. This is now a balanced equation

So: Chemical equations are balanced, when the numbers and kinds of atoms on each side of the reaction arrow are equal. H H O H O O H O H H H H Products Reactants 4 Hydrogen 4 Hydrogen 2 Oxygen 2 Oxygen

Because atoms are conserved, the mass of the reactants in the chemical reaction is equal to the mass of the products. H2 + F2  2 HF 2g + 38g = 2( 20g) 40g = 40g H F H F F H Reactants Products 40 g 40 g

Law of Conservation of Matter (Mass) If the amount of matter (mass) was not the same before and after the change (remember, it is the law), you must offer an explanation as to why.

Sometimes in chemical reactions mass is converted to a gas and/or energy that it is released as a product.