Classifying Reactions Lab

Classifying Reactions Lab Name Date  Unit 5, Lesson 12 Classifying Reactions Lab   Safety Reminder: Wear safety glasses and use ammonia in a well-ventilated area. Objectives: Identify different types of reactions Predict the products of reactions Balance chemical equations

Materials Needed for Whole Lab Small glass jars (2) Steel wool Water Dish with sides Hydrogen peroxide Potato Penny Sandpaper or nail file Small bowl Penny dated after 1983 Vinegar Epsom salts Ammonia Small cup Measuring cup

Part I: Reaction between Iron and Oxygen Part I Materials: small glass jars dish with sides (a pie plate works well) Steel wool Water

Part I: Reaction between Iron and Oxygen Part I Procedures:  Soak a small piece of steel wool in vinegar for one minute. Use tweezers to push the steel wool around in the vinegar to remove bubbles.  Lift the steel wool out of the vinegar with tweezers and shake it gently over a paper towel to remove excess vinegar. Stretch the wool out. Gently push the steel wool into the bottom of a baby jar. Add water to a small bowl until the water is about three-quarters of an inch deep. Invert the baby food jar and place it in the bowl of water. No water should be inside the baby food jar at this point (you have trapped air in the baby food jar). Leave for 20 minutes and then record observations.

Part I Questions and Conclusions Reaction between iron and oxygen 1. Balance the equation, if necessary, for the reaction between iron and oxygen. Fe + O2  Fe2O3 Hint: There must be the same number of Fe’s and O’s on each side of the arrow. 2. Classify the reaction that occurred between the iron and oxygen. Hint: Is something being produced? Choices: Synthesis, Decomposition, Single Replacement, Double Replacement. 3. What evidence was there that a reaction took place? Hint: What were your observations? -Indicators of a chemical reaction: A transfer of energy A change in color The production of gas (bubbles) The formation of a precipitate (the appearance of a solid after two solutions are mixed)

Part II: Decomposition of hydrogen peroxide Part II Materials hydrogen peroxide small pieces of raw potato (yeast or beef liver may be substituted for the potato) small bowl

Part II: Decomposition of hydrogen peroxide Part II: Procedure Pour one third of a cup of hydrogen peroxide into a small bowl. Cut up several small pieces of raw potato and place them in the hydrogen peroxide. Record your observations.

Part II Questions and Conclusions Decomposition of hydrogen peroxide  1. The potato (as well as the yeast and beef liver) contains an enzyme called catalase, which breaks down hydrogen peroxide. Balance the equation, if necessary, for the breakdown of hydrogen peroxide.   H2O2  H2O + O2 Hint: There must me the same number of H’s and O’s on each side of the equation.   2. Classify the reaction that occurred as hydrogen peroxide was broken down. Hint: The words “broken down” gives a clue! Choices: Synthesis Decomposition, Single Replacement, Double Replacement. 3. What evidence was there that a reaction was taking place? Hint: What were your observations? -Indicators of a chemical reaction: A transfer of energy A change in color The production of gas (bubbles) The formation of a precipitate (the appearance of a solid after two solutions are mixed)

Part III: Reaction between zinc and acetic acid Part III Materials: a penny dated after 1983 metal file or coarse sandpaper vinegar

Part III: Reaction between zinc and acetic acid Part III Procedures Use a file or sandpaper to completely remove the copper from the edge of a penny. Once the copper is removed you can see the silvery zinc that composes the core of the penny. Place the penny into a small jar of vinegar so that the penny sits upright. This will allow the hydrogen gas to readily escape and increase the rate of reaction. Allow the container to stand undisturbed for 30 minutes. Record your observations.

Part III: Reaction between zinc and acetic acid Rub the surface off of the penny with sandpaper or a nail file. Make sure you leave it undisturbed in the vinegar for at least 30 minutes, maybe longer.

Part III Questions and Conclusions Reaction between zinc and acetic acid 1. Balance the equation, if necessary, for the reaction between zinc and acetic acid.   Zn + CH3COOH  Zn(CH3COO)2 + H2 Hint: There must be the same number of Zn’s, H’s, C’s, and O’s on each side of the arrow. Don’t forget to distribute the 2 to all of the atoms inside the parenthesis. 2. Classify the reaction between zinc and acetic acid. Hint: Is it a single or double replacement reaction?   3. What evidence was there that a reaction was taking place? Hint: What were your observations? -Indicators of a chemical reaction: A transfer of energy A change in color The production of gas (bubbles) The formation of a precipitate (the appearance of a solid after two solutions are mixed)

Part IV: Reaction between magnesium sulfate and ammonia Part IV Materials Epsom salts (MgSO4) ammonia (NH4OH) small jar or cup measuring cup

Part IV: Reaction between magnesium sulfate and ammonia Part IV Procedures Dissolve 1 teaspoon of Epsom salts in a half cup of water. Add 2 teaspoons of ammonia to the Epsom salts solution and stir thoroughly. Record your observations. Allow the mixture to stand for 30 minutes and record your observations.  

Hint: Is it a single replacement or a double replacement? Part IV Questions and Conclusions Reaction between magnesium sulfate and ammonia  1. Balance the equation, if necessary, for the reaction between magnesium sulfate and ammonia.   MgSO4 + NH4OH  (NH4)2SO4 + Mg(OH)2 Hint: There must be the same number of Mg’s, (SO4 )‘s, (NH4)’s and (OH)’s on each side of the arrow. 2. Classify the reaction between magnesium sulfate and ammonia. Hint: Is it a single replacement or a double replacement? 3. What evidence was there to indicate that the Epsom salts and ammonia reacted? Hint: What were your observations? -Indicators of a chemical reaction: A transfer of energy A change in color The production of gas (bubbles) The formation of a precipitate (the appearance of a solid after two solutions are mixed)