Wednesday, January 21, 2015 Get your lab notebook from the cabinet! Pick up all three handouts and three different colored pieces of paper. Bellwork: Complete the vocabulary word search – turn it in when you are done! Today: Begin unit on Chemical Reactions

Spring Semester Lab Notebooks

Chemical Reactions 1.Vocabulary 2.Evidence of a Chemical Reaction 3.Balancing Equations 4.Classifying Chemical Equations 5.Reactions in Aqueous Solutions

Chemical Reactions - Vocabulary A chemical reaction is the process by which the atoms of one or more substances are rearranged to form different substances.

Chemical Reactions - Vocabulary Reactants are the starting substances Products are the ending substances 2Li + 2H 2 0  2LiOH + H 2 ProductsReactants

Chemical Reactions - Vocabulary

A chemical equation is a statement that uses chemical formulas to show the identities and amounts of substances involved in a chemical reaction. Na + Cl  NaCl 6CO H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O

Chemical Reactions - Vocabulary A coefficient is the number written in front of a reactant or product. These indicate how many of each compound are present in the reaction 2A + 2B  2AB 6CO H 2 O  C 6 H 12 O 6 + 6O 2 + 6H 2 O

Chemical Reactions - Vocabulary A precipitate is a solid produced during a chemical reaction.

Chemical Reactions - Vocabulary

A catalyst is a substance that speeds up the rate of the reaction but is not used up in the reaction. It can be heat, energy, pressure, or a chemical substance. These are not generally written in chemical equations.

Chemical Reactions - Vocabulary An aqueous solution is contains one or more solutes dissolved in water. A solute is the substance that is dissolved in the solution. A solvent is the liquid the solute is dissolved in. In aqueous solutions, the liquid is water.

Chemical Reactions - Vocabulary Foldable Instructions Use 3 different colored pages Words: chemical reaction, chemical equation, aqueous, solvent, solute, precipitate, catalyst, reactant, product, coefficient. Write the definition, then summarize the definition in your own words (or a “memory jog”), then use the word in a sentence.

Evidence of a Chemical Reaction  Temperature change  Release of heat and/or light  Absorption of heat  Color change rusty nails bananas  Gas bubbles  Odor (release of a gas)  Formation of a precipitate

Representing Reactions (Writing Equations) Word equations Aluminum (s) + Bromine (l)  aluminum bromide (s) Skeleton equations Al (s) + Br 2 (l)  AlBr 3

Chemical Equations  Use formula units  Indicate how much of each compound/element is part of the reaction  The Law of Conservation of Mass means however much of each element you started with, you must also end up with (balancing equations)

Balancing Chemical Equations To balance a chemical equation, you must find the correct coefficient for the chemicals found in the skeleton equation. Skeleton: Al + Br 2  AlBr 3 Balanced Equation: 2Al + 3Br 2  2AlBr 3

Balancing Equations Steps for balancing equations 1.Write the skeleton equation for the reaction. 2.Count the atoms of the elements in the reactants. 3.Count the elements in the products 4.Change the coefficients so you have the same number of atoms on both sides of the equation. 5.Write the coefficients in their lowest possible ratio. 6.Check your work. Make sure your formula units are correct, and that the number of atoms on both sides are equal.

Balancing Equations Write the balanced equation for the reaction in which aqueous sodium hydroxide and aqueous calcium bromide react to produce solid calcium hydroxide and aqueous sodium bromide. Step 1: Write the skeleton equation NaOH (aq) + CaBr 2 (aq)  Ca(OH) 2 (s) + NaBr(aq)

Write the balanced equation for the reaction in which aqueous sodium hydroxide and aqueous calcium bromide react to produce solid calcium hydroxide and aqueous sodium bromide. NaOH (aq) + CaBr 2 (aq)  Ca(OH) 2 (s) + NaBr(aq) Step 2 & 3: Count the number of atoms of the products and the reactants Reactants Na: 1OH: 1 Ca: 1Br: 2 Products Ca: 1OH: 2 Na: 1Br: 1

NaOH (aq) + CaBr 2 (aq)  Ca(OH) 2 (s) + NaBr(aq) Step 4: Change the coefficients 2NaOH + CaBr 2  Ca(OH) 2 + NaBr 2NaOH + CaBr 2  Ca(OH) 2 + 2NaBr

NaOH (aq) + CaBr 2 (aq)  Ca(OH) 2 (s) + NaBr(aq) Step 5: Are they in their lowest possible ratio? 2NaOH + CaBr 2  Ca(OH) 2 + 2NaBr Coefficient ratio is 2:1:1:2

NaOH (aq) + CaBr 2 (aq)  Ca(OH) 2 (s) + NaBr(aq) Step 6: Check your work and make sure you have the same number of atoms of each element on both sides of the equation. 2NaOH + CaBr 2  Ca(OH) 2 + 2NaBr Products: Na: 2 OH: 2 Ca: 1 Br: 2 Reactants: Na: 2 OH: 2 Ca: 1 Br: 2

Homework Complete the balancing equation worksheet. Use a PENCIL. Due Thursday! BYD Class Competition on Friday! Find help at chemistry.about.com and chemtutor.com/react.htm

Thursday, January 22 Today is a BYD Day! Have your smartphone out, face down on the forward right corner of your desk. If you don’t have a smartphone, don’t worry, just pair up wth someone who does. TURN IN YOUR BALANCING EQUATIONS HOMEWORK Bellwork: Balance the reaction of hydrogen sulfide with atmospheric oxygen gas to form sulfur dioxide and water. Balance the following: (NH 4 ) 2 Cr 2 O 7 (s)  Cr 2 O 3 (s) + N 2 (g) + H 2 O(g)

Balancing Equations Write a skeleton equation for photosynthesis (the reaction of carbon dioxide and water to form glucose and atmospheric oxygen) CO 2 (g) + H 2 O(l)  C 6 H 12 O 6 (s) + O 2 (g)

Balancing Reactions Now let’s balance it. CO 2 (g) + H 2 O(l)  C 6 H 12 O 6 (s) + O 2 (g)

Balancing Chemical Equations kahoot.it Top 3 winners get a Homework Pass

Chemical Reactions 1.Vocabulary 2.Evidence of a Chemical Reaction 3.Balancing Equations 4.Classifying Chemical Equations 5.Reactions in Aqueous Solutions

Types of Chemical Reactions 1.Synthesis Reactions 2.Combustion reactions 3.Decomposition Reactions 4.Replacement Reactions a.Single-replacement reactions b.Double-replacement reactions

Types of Chemical Reactions A synthesis reaction is a reaction where two or more substances combine (react) to form one single substance. A + B  AB Na + Cl  NaCl 2SO 2 + O 2  2SO 3

Types of Chemical Reactions Write a chemical equation for the following reaction: The solids aluminum and and sulfur react to form aluminum sulfide.

Types of Chemical Reactions In a combustion reaction, oxygen combines with a substance and releases heat and light. AB + O  AO +B 2H 2 + O 2  2H 2 O + energy 2C 8 H O 2  16CO H 2 O + energy

Types of Chemical Reactions Write a chemical equation for the following: The gases nitrogen dioxide and oxygen react to form dinitrogen pentoxide gas. Which types of reactions does this fall under?

Types of Chemical Reactions Decomposition reactions are where a single compound breaks down into two or more elements or compounds. Essentially, it’s a backwards synthesis reaction. AB  A + B NH 4 NO 3  N 2 O + 2H 2 O

Types of Chemical Reactions Write a chemical equation for the following: Aluminum oxide (a solid) decomposes when electricity passes through it.

Types of Chemical Reactions In single replacement reactions, the atoms of one element replace the atoms of another element in a compound. A + BX  AX + B Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2

Types of Chemical Reactions Single replacement reactions Metal replaces hydrogen or another metal 2Li + 2H 2 O  2LiOH(aq) + H 2 (g) Cu + 2AgNO 3  2Ag + Cu(NO 3 ) 2

Types of Chemical Reactions Single Replacement Reactions Nonmetal replaces nonmetal F 2 + 2NaBr  2NaF + Br 2

Types of Chemical Reactions Single Replacement Reactions Predict what’s going to happen: Fe (s) + CuSO 4 (aq)  Br 2 (l) + MgCl 2 (aq) 

Types of Chemical Reactions In double-replacement reactions, ions are exchanged between two compounds. AX + BY  AY + BX 2NaOH + CuCl 2  2NaCl + Cu(OH) 2 Ca(OH) HCl  CaCl 2 + 2H 2 O

Types of Chemical Equations All double-replacement reactions produce either water, a precipitate (a solid), or a gas. KCN (aq) + HBr (aq)  KBr (aq) + HCN (g) LiI (aq) + AgNO 3  AgI (s) + LiNO 3 (aq) CH 3 COOH(aq) + KOH (aq)  CH 3 COOK (aq) + H 2 O (l)

Types of Chemical Reactions Write and balance this reaction equation. Aqueous barium chloride and aqueous potassium carbonate react to form solid barium carbonate and aqueous potassium chloride. What kind of reaction is this?

Types of Chemical Reactions Write and balance this reaction equation. Aqueous sodium oxalate and aqueous lead (II) nitrate react to produce solid lead (II) oxalate and aqueous sodium nitrate. What kind of reaction is this?

Homework Complete the assigned worksheets by Monday. LAB NEXT WEEK WEDNESDAY AND THURSDAY

Monday, January 26 th - Bellwork List the 5 types of chemical reactions. Balance the following reaction Na(s) + MgI 2 (aq)  NaI(aq) + Mg(s) What kind of reaction is this?

Chemical Reactions 1.Vocabulary 2.Evidence of a Chemical Reaction 3.Balancing Equations 4.Classifying Chemical Equations 5.Reactions in Aqueous Solutions

Types of Chemical Reactions Foldable for your lab notebook!

Reactions in Aqueous Solutions Remember this? a solution is a homogenous mixture An aqueous solution is contains one or more solutes dissolved in water. A solute is the substance that is dissolved in the solution. A solvent is the liquid the solute is dissolved in. In aqueous solutions, the liquid is water

Reactions in Aqueous Solutions Some compounds exist as molecules in aqueous solutions. Some compounds can form ions when in an aqueous solution Example: HCl forms H + and Cl - ions when dissolved in water. HCl(aq)  H + (aq) + Cl - (aq) This is called dissociation.

Types of Reactions in Aqueous Solutions 1.Reactions that form precipitates 2.Reactions that form water 3.Reactions that form gases

Reactions in Aqueous Solutions 1. Reactions that form precipitates Double-replacement reaction Example: 2NaOH(aq) + CuCl 2  2NaCl (aq) + Cu(OH) 2 (s)

Reactions in Aqueous Solutions Ionic equations are different from chemical equations in that the ions in solution are written as ions in the equation. A complete ionic equation is one that shows all the particles in a solution as they exist. 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)  2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s)

Reactions in Aqueous Solutions Ions that do not participate in the reaction are called spectator ions. Net ionic equations only show the ions that participate in the reaction.

Reactions in Aqueous Solutions 2Na + (aq) + 2OH - (aq) + Cu 2+ (aq) + 2Cl - (aq)  2Na + (aq) + 2Cl - (aq) + Cu(OH) 2 (s) 2OH - (aq) + Cu 2+  Cu(OH) 2 (s)

Reactions in Aqueous Solutions Demo: 2NaOH(aq) + CuCl 2  2NaCl (aq) + Cu(OH) 2 (s)

Reactions in Aqueous Solutions 2. Reactions that form water These reactions are double-replacement reactions Usually no evidence that a chemical reaction has occurred, because the water produced would not be visible in the solution HBr(aq) + NaOH (aq)  H 2 O(l) + NaBr(aq)

Reactions in Aqueous Solutions Balanced equation: HBr(aq) + NaOH (aq)  H 2 O(l) + NaBr(aq) Complete ionic equation H + (aq) + Br - (aq) + Na + (aq) + OH - (aq)  H 2 O(l) + Na + (aq) + Br - (aq) Net ionic equation H + (aq) + OH - (aq)  H 2 O(l)

Reactions in Aqueous Solutions 3. Reactions that form gases Also double-replacement reactions Balanced equation 2HI(aq) + Li 2 S(aq)  H 2 S(g) + 2LiI(aq) Complete ionic equation 2H + (aq) + 2I - (aq) + 2Li + (aq) + S -2 (aq)  H 2 S(g) + 2Li + (aq) + I - (aq)

Reactions in Aqueous Solutions Write (and balance) the equation for the reaction of vinegar (CH 3 COOH H2O) and baking soda (NaCHO 3 ). What’s the complete ionic equation? What’s the net ionic equation? What kind of reaction is this?

QUIZ! Take the lab packet home and answer the pre-lab questions. Remember – no flowy sleeves, no sandals, and if you have long hair, bring something to tie it up with! Lab Wednesday