At the end of the class show them again. Writing and Balancing Chemical Reactions Study Guide Purpose: Once the instruction for the unit is completed, students can complete this study guide to aid in their preparation for a written test. This is simple and an effective way to illustrate this type of reaction. I follow this by writing the synthesis equation, H 2 + O 2 à H 2O on the board and explain that when hydrogen and oxygen are combined they make water and release a lot of energy. They are told to use their notes to aid them in this. The predicting portion of the lesson was not the main focus of the assignment; however, they will have to recognize the products present in a combustion reaction and single replacement reactions. You can use smaller amount of each to produce less waste.
I ask them to image what the Hindenburg looked like as it was going down. Essential Concepts: Chemical reactions, single-replacement reactions, synthesis reactions, alkali metals, periodic law. Most students had no difficulty completing the types of reaction and balancing portion of the worksheet. Use filter paper to separate the solid from the liquid. Let dry and dispose of in the garbage when dry. I find the best way to help student take notes is to make them as interactive as possible. After everyone has written the notes and seen the last demo I hand the homework out.
The next day's lab activity will give them more practice in predicting products. Writing and Balancing Single Replacement Reactions Purpose: Single-replacement reactions involve reacting a lone element usually a metal with a compound, resulting in the cations switching places. Student were introduced the previous day to the 5 different chemical reactions that show that conservation of mass can occur several of ways during a chemical reaction. If you have difficulty igniting it the first time, add a little more alcohol, swirl and try again. Students are expected to see that patterns exist in each of the 5 types of reactions they and be able to recognize each reaction based on these patterns. The focus of this chapter is primarily on the basic mechanics of writing out and predicting the results of chemical reactions. The study guide is divided into two sections: vocabulary and short answer questions.
The short answer questions are conceptual and meant to see if the students are able to apply what they've learned in the unit. Slide Explanation and Demo All Demos should be done wearing goggles and an apron. Writing and Balancing Synthesis Reactions Purpose: Predicting the products and balancing chemical reactions is the main skillset that students need to have leaving this chapter. Chemical Reactions Having completed the prior unit on atomic structure and the naming of elements and compounds, the students are now ready to start looking at how atoms and molecules can rearrange themselves during chemical reactions. During this process they were building a personal understanding of reaction types that might not necessarily be 100% accurate, but can be used as a scaffold to create a deeper understanding through formal explanation lecture. Essential Concepts: Chemical reactions, combustion, activation energy. I than tell them we are going to try this again, but this time cover your ears.
The first one contains helium, the second contains a small amount cantaloupe size balloon of hydrogen gas and the third is filled with a mixture of 75% hydrogen and 25% oxygen a little smaller than the previous balloon. This provides reinforcement for the lab the following period. This activity will help them recall what was learned from the previous day. Mythbusters - Cell Phone Destruction Worksheet Purpose: This segment of Mythbusters focuses on combustion. Essential Concepts: Chemical reactions, synthesis reactions, balancing equations, predicting products, oxidation state. Next I do the same with the hydrogen filled balloon.
Mythbusters - Alkali Metal Mayhem Worksheet Purpose: In this episode of Mythbusters, they debunk a Braniac video viewable on Youtube that demonstrates an explosion produced by dropping cesium into a bathtub of water that is powerful enough to actually crack the bathtub. The analogy provides another way for students to scaffold the information into a deeper understanding. Each slide and demo takes about 7 minutes. Students will need to copy of a t to be able to complete these worksheets. Writing and Balancing Double-Displacement Reactions Purpose: Double-displacement reactions involve the switching of cations between two compounds.
The answer is no, as there is a level of activation energy needed to initate combustion that simply is not present in the electromagnetic emissions of a cell phone. Writing and Balancing Decomposition Reactions Purpose: This worksheet is a good followup to the synthesis reactions worksheet, because all of the same rules and ideas apply, simply in reverse. The vocabulary words can be found scattered throughout the different instructional worksheets from this unit. This is not the main focus of the unit but it does need to be covered. Typically they forget that some elements form diatomic molecules and also don't correctly write the chemical formulas. Included is information on the state of matter notation that indicates whether each substance is a solid, liquid, gas, or aqueous solution. To start the class, I have each student write down on a single sheet of paper one example of each.
Some students had some difficulty predicting the products because they have only had limited exposure to the concept. After explaining all the information on the slide, I perform a demo that illustrates the reaction type. This worksheet provides a few examples of how to predict products of synthesis reactions using oxidation states as well as showing students how to balance. A simplified solubility table is included as part of this assignment. Starting with the relatively simple synthesis and decomposition reactions, we work our way up through single replacement, double displacement, and combustion.