CHEMISTRY November 10, 2011

Brain Teaser  Identify the type of reaction:  H 2 + O 2  H 2 O  CaSO 4 + KOH  Ca(OH) 2 + K 2 SO 4  KClO 3  KCl + O 2  AgNO 3 + Cu  Cu(NO 3 ) 2 + Ag  Write the chemical equation:  Magnesium reacts with chlorine gas in the air to form magnesium chloride

Agenda  Brain Teaser  Review Types of Reactions  Notes: Balancing Equation  Cool Chemical Reactions Mini-Lab  Homework  Complete Reaction Types Worksheet 1  Balance Equations in Lab Packet

Review  4 Types of Chemical Reactions  Synthesis: A + B  AB (1 product)  Decomposition: (1 reactant) AB  A + B  Single replacement: X + AB  XB + A  Double replacement: AB + XY  AY + XB

Balancing Equation Word Equations  Describes a chemical reaction that occurs using the names of the chemicals involved.  Reactants versus Products  An arrow is written between the reactants and products to indicate that chemical change is occurring  For example: 2H 2 + O 2  2H 2 O

Balancing Equation  Atoms involved in a chemical reaction must be balanced.  Same number of atoms of each element on both sides of a chemical equation.  Unbalanced equation  Balance the equation by adding coefficients in front of the compounds Coefficients: number of molecules of a particular compound Subscripts: number of atoms of each element in the compound

Balancing Equation A. Write the word equation B. Write the CORRECT formula for all reactants and products C. Balance the equation by using coefficients 1. NEVER change the subscripts in the formula to balance the equation 2. Elements need to be balanced from either side of the equation 3. Start with the first element and work right of the equation 4. Balance the number of oxygen and hydrogen atoms after all the other elements have been balanced. 5. Go back and double check that all elements are balanced 6. BOX your coefficients when finished 7. USE PENCIL only!

Balancing Equation  Inspection Method  Algebraic Method

Balancing Equation  Inspection Method  Aluminum reacts with oxygen to produce aluminum oxide  Chlorine reacts with lithium bromide to produce lithium chloride and bromine gas

Balancing Equation  Algebraic Method  Aluminum oxide reacts with sodium phosphate to produce aluminum phosphate and sodium oxide  Hydrogen gas and nitrogen monoxide react to form water and nitrogen gas

Practice Problems  ___Ca(CN) 2 + __AlF 3  __CaF 2 + ___Al(CN) 3  Potassium phosphate + Calcium hydroxide  Calcium phosphate + Potassium hydroxide

Balancing Chemical Equations  Refer to Practice Worksheet

Cool Chemical Reactions  Objectives: Write 4 chemical equations to explain the chemical reactions Balance the equations Record qualitative observations  Procedures:  Read each procedure carefully before beginning. Goggles are required!  Restore Station Before Switching  DO NOT dump any chemicals down the sink Waste  Waste Container DO NOT cross contaminate chemicals Burning Split Test Oxygen Gas  Carbon Dioxide Gas  Hydrogen Gas 

Cool Chemical Reactions  Station 1: The Sparkler  Hold Mg strip with tongs and ignite with Bunsen burner  Station 2: The Fire Extinguisher  Place 1 little scoop of sodium bicarbonate (2 cm deep) into a test tube  Add drops of HCl slowly into the test tube (fizz)  Have a burning splint ready to test for the gas produced  Discard solution into the sink and was clean test tube

Cool Chemical Reactions  Station 3: Spy Writing  Dip one end of Q-tip in lead (II) nitrate  Draw and Let it Dry  Dip other end of Q-tip in potassium iodide  Wipe over writing. Let it dry  Dipose Q-tip in Waste Container. Wash your hands!  DO NOT TOUCH the chemicals on the paper!

Cool Chemical Reactions  Station 4: Hear it Pop  Add a piece of Mg ribbon into a test tube  Add 1 pipette full of 3M hydrochloric acid  Immediately place a stopper on the test tube to collect the gas produced  Have a burning splint ready to test for the gas produced. Remove the stopper and test for gas  DO NOT submerge splint into the liquid (DEMO)  Discard content into Waste Beaker

Cool Chemical Reactions  A. Procedure (NEED TO WEAR GOGGLES!)  B. Observations: Refer to Handout  C. Write the chemical equation and BALANCE!  Don’t forget Cl 2, I 2, F 2, Br 2, O 2, H 2, N 2  D. Refer to the handout

Cool Chemical Reactions Lab Report Refer to Rubric