To launch our Toxins Research Project, students are tasked with researching key information about five toxins of interest to them. Information will be recorded on the Toxins Research Project handout (Day 1) which is due at the end of class.
The websites below are useful for getting started:
For the final lesson of Chapter 14, we worked through the Lesson 79 PowerPoint in which we ultimately compared the toxicities of regular and diet soda, containing fructose and aspartame, respectively. Students then received the Lesson 79 Worksheet to work through for the remainder of class. As a reminder, we have a mini-quiz on Thursday, so students should come to class tomorrow prepared with questions from our work in Chapter 14 (Lessons 74-79) and from the Chapter 13/14 Study Guide.
Class began with a review of the connection between moles and particles. From there, students worked through an entry task requiring them to balance a combustion reaction, calculate atomic masses of the products and reactants from the reaction, and then to compare the results (thus demonstrating conservation of mass).
Next, students had the remainder of the class period to work through the Relative Mass and the Mole POGIL packet. Key concepts from textbook lessons 76-78 are distilled into a PowerPoint slide deck from students who desire additional review.
Our work today involved a Counting By Weighing activity. Students recorded the mass of a small number of objects to then estimate the mass of a much larger number of objects. The activity was designed to help students begin to make sense of the mole, a unit of chemistry that represents 6.02 x 10^23 of any given object. In chemistry, we use the mole as a way to measure the number of atoms or molecules. Students also received a copy of the Chapter 13/14 Study Guide as a tool to begin preparing for the quiz next Tuesday.
Class began with students receiving back their mini-quiz from last week which we reviewed together as a class. Students were reminded that all work from lessons 70-73 (chapter 13) must be turned in no later than tomorrow for credit. After the review, students voted on one of two options:
Continue forward with Lesson 74: Toxicity
Conduct an experiment focused on the combustion reaction
Students elected to learn about the combustion reaction, so we reviewed the combustion of propane and balanced the equation, then carried out an experiment in which a candle (made of paraffin wax, another hydrocarbon) is combusted under a bell jar. We timed how long the candle burned for, and also measured the amount of oxygen and carbon dioxide in the room (before combustion) and under the bell jar (after the candle extinguished.
Next, we wrote the chemical equations for combining hydrogen peroxide and bleach (producing oxygen) and for combining baking soda and vinegar (producing carbon dioxide). We evaluated the effect of combustion in the presence of excess oxygen or carbon dioxide, measuring how long the candle burned as our endpoint. Class notes are provided below.
We will return to our regularly scheduled programming (lesson 74) tomorrow!
In the first lesson of Chapter 14, students were introduced to the concept of LD50 (the dose of a compound that is lethal to 50% of the population). As our entry task, students considered the following:
Which substance do you think is most toxic to you –
Alcohol (ethanol, C2H6O)
Aspirin (salicylic acid, C7H8O3)
Arsenic (III) oxide (As2O3)
Explain your thinking
We then identified the LD50 values for all three substances using the Lethal Doses Handout. We discussed the meaning of LD50 (the lethal dose at which 50% of rats die after exposure to a given amount of a substance, often expressed in mg/kg) and students were shown a Material Safety Data Sheet (MSDS) for water (toxic at >90 mL/kg), providing students with evidence that all substances are toxic at high enough levels. Students then received the Lesson 74 Worksheet to work on during class time.
Notes from class:
Extend Your Learning!
Wondering about how scientists define the kilogram? Turns out the way we define the kilogram just changed late last year. Read about it at PBS.org or watch the video below:
For the final lesson of chapter 13, students learned to classify the types of reactions as combination, decomposition, single exchange, or double exchange reactions.
Combination: A + B -> C
Decomposition: A -> B + C
Single Exchange: AB + C -> A + BC
Double Exchange: AB + CD -> AD + CD
We focused primarily slide 8 of the Lesson 73 PowerPoint. Students are encouraged to review the full slide deck, including the vocabulary defined on slides 9-12. Students then received the Lesson 73 Worksheet and Toxic Reaction Cards to work on for the remainder of class. As an alternative, students who self-assessed as needing additional practice balancing equations were offered the opportunity to work through the Balancing Equations Gizmo.
Class began with the ChemCatalyst from the Lesson 72 PowerPoint. With the lesson focusing on balancing chemical equations, we worked through the ChemCatalyst equation with a focus on differentiating coefficients and subscripts (slides 11 and 12). We used the remainder of the class period to practice balancing equations.
Notes from the whiteboard:
For students who would like additional instruction around balancing equations and enjoy learning by watching videos, I recommend Tyler DeWitt’s videos Introduction to Balancing Equations (above) and Balancing Chemical Equation Practice Problems (below):
For our introductory lesson of Unit 4, we revisited the concepts of physical and chemical change in the context of chemical reactions. The lesson began with a demonstration in which students were presented with a chemical equation, observed the chemical reaction, and then were challenged to prove whether the predicted product could be observed. The demonstration led to a discussion of physical and chemical change via the Lesson 70 PowerPoint which includes an image of the following reaction: Cobalt (II) chloride (a solid with a rich blue color) + water (clear liquid) reacts to form a pink liquid. Students had the remainder of the class period to complete the Lesson 70 Worksheet. Class notes are shown below: