UNIT 6 Chemical Reactions You Will Need The Following: Chromebook - Notebook Reference Tables

Pre-Assessment: Work w/ Shoulder Buddy What are the 4 indicators a chemical reaction has taken place? ____H2 (g) +____ O2 (g) ➔_______H2O (g) Use balanced equation above to complete the chart: What are the reactants? What are the products? How many oxygen atoms start the reaction? How many oxygen atoms end the reaction? Which substance(s) are gases in the reaction above?

Objectives By the end of today’s class you will be able to: Recall the 4 signs of a chemical reaction Identify the parts of a chemical equation Understand the 1st Law of Conservation of Matter Identify diatomic elements Balance Chemical Equations

Warm up After 24.0 days, 2.00 milligrams of an original 128.0 milligram sample remain. What is the half-life of the sample? How many electrons are in the 3rd shell (energy level) of an atom with an atomic number of 23? Correct ALL Errors…. Cr2(SO3)3 = Dichromium sulfide 4. Identify the Alkaline Earth Metal in Period 3. 5. Write the noble gas notation for the Period 5 Halogen

What is a Chemical Reaction? A change in the arrangement of atoms. New substances are formed ..

What is a chemical equation? Chemical equation – Written description of a chemical change. Shows the atoms present in the reactants and rearrangement of atoms to form products Parts of an equation: Reactant Product 2Ag + H2S Ag2S + H2 Yields or Produces

Symbols Symbol Meaning + Plus or reacts with → Yields or Produces (s) Solid (l) Liquid (g) or Gas (aq) Aqueous (dissolved in water) Δ Heat is added to the reaction https://quizlet.com/11378655/symbols-used-in-chemical-equations-flash-cards/

Diatomics – in elemental form there are 2 atoms bonded together . H2, N2, O2, F2, Cl2, Br2, I2 Tricks to remember I Bring Clay For Our New House Or: Start at 7, make a 7, add hydrogen

Tricks to remember the DIATOMIC ELEMENTS I Bring Clay For Our New House Or: Start at 7, make a 7, add hydrogen H N O F Cl Br I

Reactants and Products Reactant - The chemical(s) you start with before the reaction. Written on left side of equation. Product - The new chemical(s) formed by the reaction. Right side of equation.

Subscripts and Coefficients Subscript - shows how many atoms of an element are in a molecule. EX: H2O 2 atoms of hydrogen (H)‏ 1 atom of oxygen (O)‏ Coefficient - shows how many molecules there are of a particular chemical. EX: 2 H2O Means there are 2 water molecules.

A Chemical Reaction 2H2 + O2  2H2O

Law of Conservation of Mass In a chemical reaction, MATTER is neither created nor destroyed. In other words, the number and type of atoms going INTO a rxn must be the same as the number and type of atoms coming OUT. If an equation obeys the Law of Conservation, it is balanced.

Watch and Learn Watch the video through 6 minutes http://www.bozemanscience.com/beginners -guide-balancing-equations/

An Unbalanced Equation CH4 + O2  CO2 + H2O Reactant Side Product Side 1 carbon atom 4 hydrogen atoms 2 oxygen atoms 1 carbon atom 2 hydrogen atoms 3 oxygen atoms

A Balanced Equation CH4 + 2O2  CO2 + 2H2O Reactant Side Product Side 1 carbon atom 4 hydrogen atoms 4 oxygen atoms 1 carbon atom 4 hydrogen atoms 4 oxygen atoms

Rules of the Game 1. Matter cannot be created or destroyed. 2. Subscripts cannot be added, removed, or changed. 3. You can only change coefficients. 4. Coefficients can only go in front of chemical formulas...NEVER in the middle of a formula.

A few extra tips: If the same polyatomic ion appears on both sides of the equation, it’s usually okay to treat it as one unit. Sometimes it is useful to write water as H(OH) to balance with an hydroxide ion Balance elements (single or diatomic) LAST THIS IS A TRIAL AND ERROR PROCESS Be Patient!

Balancing Equations 3 2 2 2 1 6 2 6 3 N2 + H2  NH3 N H Balance the following equation by adjusting coefficients. N2 + H2  NH3 3 2 reactants products N 2 2 1 6 2 6 3 H

Balancing Equations 3 2 2 2 1 1 2 2 1 2 1 6 3 2 6 KClO3  KCl + O2 K Balance the following equation by adjusting coefficients. 3 2 KClO3  KCl + O2 2 reactants products K 2 1 1 2 Cl 2 1 2 1 6 3 2 6 O

Simple Balancing ____ P4 + ____ O2  ____ P2O5

Simple Balancing ____ Ag2O  ____ Ag + ____ O2

You Try!!! ____ S8 + ____ O2  ____ SO3 ____ K + ____ MgBr2  ____ KBr + ____ Mg

Equations with Polyatomic Ions __ AgNO3 + __ MgCl2  __ AgCl+ __ Mg(NO3)2

You Try!!! ____ FeCl3 + ____ NaOH  ____ Fe(OH)3 + ____ NaCl

Combustion Reactions ____ CH4 + ___ O2  ___ CO2 + ___ H2O Balance the atoms alphabetically ____ CH4 + ___ O2  ___ CO2 + ___ H2O

Combustion Reactions ____ C6H6 + ___ O2  ___ CO2 + ___ H2O THIS ONE IS A STINKER!! ____ C6H6 + ___ O2  ___ CO2 + ___ H2O

Practice using the phet simulation https://phet. colorado Practice using the phet simulation https://phet.colorado.edu/sims/html/balancing- chemical-equations/latest/balancing-chemical- equations_en.html

EXIT TICKET __SeCl6 + __O2  __SeO2 + __Cl2 __ KCl + __ CaCO3  __ CaCl2 + __ K2CO3

HOMEWORK Balancing Equations WS 1 Identify Reactants & Products: all Balance The Equations: Even #s Only

Review and Practice Atom Math Nuclear Decay Periodic Behavior Periodic Trends (Ordering Elements) Lewis Structures Mole Math