Chemical Reactions Part 1 and 2

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Chemical Reactions Part 1 and 2
By Lacey

Discovering Chemical Reactions
Part 1

Overview

Subject(s):
Science

Grade:
6

Summary & Rationale:
Students carefully observe three chemicals using several of their senses. This experience
leads students to discover firsthand what a chemical reaction is; the teacher just needs to give them a name for what they have observed. Students are usually full of questions about reactions, providing the teacher with a natural way to provide information about reactants, products, endothermic and exothermic. Ultimately, this experiment provides direct experiences for discussion.

Pre-teaching Tasks

Standards:

AZ- Arizona Academics Standards
• Subject : Science (previous)

• Standard 1: Science As Inquiry.
Students understand and use the processes of scientific investigation and scientific ways of knowing. They are able to design, conduct, describe and evaluate these investigations. They are able to understand and apply concepts that unify scientific disciplines.

• Grade Range : ESSENTIALS (Grades 4-8)
Students know and are able to do all of the above and the following:

• Key Idea/Concept 1SC-E1: Identify a question, formulate a hypothesis, control and manipulate variables, devise experiments, predict outcomes, compare and analyze results, and defend conclusions

• Grade : Grades 6-8

Performance Objective PO 3: Analyze the results of an experiment

Additional Standards (TESOL, etc.):
AZ- Arizona English Language Learner Proficiency Standards

Strand : LISTENING AND SPEAKING

Proficiency Stage ELL I: Performance Conditions: Students at this stage comprehend simple statements and questions. They understand the general idea of basic messages and conversations that pertain to common, routine matters. Their interactions are short, face-to-face, informal, and with one person at a time or in small groups. Although students can initiate and respond to basic statements, their speech is largely guided by questions and feedback from the teacher. English learners rely heavily on repetition, gestures, and other nonverbal cues to sustain conversations. Their speech is slow. Communications that students listen to and comprehend are short and include familiar routine words. Context strongly supports their utterances.

Area : Standard English Conventions

Standard : The student will identify, describe, and apply conventions of standard English in his or her communications.

Level : Beginning

Benchmark : Speak in isolated words (usually a single noun or verb), depending heavily on gestures to express meaning.

Level : Early Advanced

Benchmark : Speak in short phrases and simple sentences using English grammatical structures and linguistic forms outlined in the Advanced Level with some errors, although the errors do not impede communication.

Objective(s):
TSW record information observed during a chemical reaction investigation in their own words.

TSW describe the characteristics of separate chemicals in their own words.

Evaluation:
Learning will be determined as the teacher navigates among the group activities. The student reactions will signify whether they are following along or not. After the small group participation is concluded, the class will assemble as whole group to discuss what they had observed.

Pre-requisite Knowledge:
Classroom safety rules:
-no smelling or touching chemicals directly
-prevent chemical cross contamination unless otherwise permitted.

Terms to Clarify:
Chemical Reaction:

*Reactants- chemicals that take part in a chemical reaction.

*Product- the new substance that form during a chemical reaction.

*Exothermic reaction- heat energy is released.

*Endothermic reaction- heat energy is absorbed. (Endothermic reactions feel cool because heat energy from your hand is absorbed by the reaction.)

Materials:

Materials and resources:
For the class:

-1.5 lbs sodium bicarbonate (baking soda)
-3 lbs. calcium chloride
-phenol red powder diluted in water
-masking tape
-1 gallon container for mixing phenol solution
-1 plastic bucket
-access to a sink
-water
-paper towels
-pair of rubber gloves

For each group of 4-6 students:
-2 wide-mouth, plastic containers
-2 teaspoons
-2 plastic stir sticks
-2 8oz squeeze bottles
-1 graduated cylinder (10ml)
-6-9 ziplock bags
-4-6 plastic vials
-4-6 copies of data sheets for Exploratory (observation) and Heat Experiments

Teaching Procedures

Opening (Set):
Last week we conducted experiments to determine what was a base, a neutral, and an acid. Today, I would like you to think about what would happen when two chemicals are mixed together! (Write responses on the board)

Guiding Questions:
If you didn't want to contaminate my body or any of my materials, how do you suppose I should measure this chemical out?

What characteristics can you actually see?

How does it feel?

How does it sound?

Instructional Input:
*Ask students what might happen when two chemicals are mixed together.... Record responses on the board.

*Remind the students about the importance of SAFETY. Model the safest way to measure and smell chemicals.

*Direct S to their pre selected group tables. Instruct them to work together to describe the three (3) chemicals WITHOUT TASTING OR TOUCHING. (Show how to use the stir sticks to "feel" a solid chemical.)

*Hold up a "Chemical Reactions" data sheet and explain that they need to record information detailing their observation. How the substance looked, felt, smells, and sounds. Must have at least five (5) descriptive words on the sheet. Discourage "looks weird" or "smells bad".

*Explain that we will add the chemicals one by one into a ziplock bag to see what happens. (Do as a whole class!)
-1 teaspoon of baking soda into bag
-2 teaspoons of calcium chloride in bag
-10ml of phenol read solution and pour into a vial.
-put vial into bag (standing it upright)
-seal the bag
-tip the vial of red phenol.
SAY: Record what you are seeing. Discuss this within your group! Write down at least five (5) descriptive words.

*Tell the students that only after the chemicals have reacted, they can open the bag CAREFULLY!
Model opening the bag so the opening is away from the eyes. Remind the S the technique scientist use to smell chemicals, by wafting with their hands.

*Have students clean up materials and sit back at their desks.

*Discuss and record student observations and responses.

*Define "scientific" terms.

*Close the lesson

Check for Understanding:
Student understanding will be apparent as they conduct their observations and investigations. There is a product of combining two chemicals, which will have the whole class "aaahhhhhhing". During the whole group discussion, the students will report the information they observed and share ideas.

Guided (Supervised) Practice:
The students will be in groups of 2-4 conducting observations of chemical reactions. The students are virtually practicing inquiry with little supervision as they find meaning and reasoning in a certain reaction.

Extended (Independent) Practice:

Lesson Closure:
Class will end with a group discussion. The class will reflect upon the experiment and share observation comments. Once all ideas are presented, the teacher will introduce the concept of chemical reaction and define the terms:

Reactants
Products
Exothermic reaction
Endothermic reaction

Determining Factors in Chemical Reactions

Overview

Subject(s):
Science

Grade:
6

Summary & Rationale:
Students predict and investigate which of three chemicals cause the chemical reaction to give off heat. This experience leads students to discover firsthand what a chemical reaction is and how different combinations cause varying results.

Pre-teaching Tasks

Standards:

AZ- Arizona Academics Standards
• Subject : Science (previous)

• Standard 1: Science As Inquiry.
Students understand and use the processes of scientific investigation and scientific ways of knowing. They are able to design, conduct, describe and evaluate these investigations. They are able to understand and apply concepts that unify scientific disciplines.

• Grade Range : ESSENTIALS (Grades 4-8)
Students know and are able to do all of the above and the following:

• Key Idea/Concept 1SC-E4: Identify and refine questions from previous investigations

• Grade : Grades 6-8

Performance Objective PO 1: Analyze the results of previous investigations

Performance Objective PO 2: Refine hypotheses from a previous investigation

Additional Standards (TESOL, etc.):
AZ- Arizona English Language Learner Proficiency Standards

Strand : LISTENING AND SPEAKING

Area : Standard English Conventions

Standard : The student will identify, describe, and apply conventions of standard English in his or her communications.

Level : Beginning

Benchmark : Speak in isolated words (usually a single noun or verb), depending heavily on gestures to express meaning.

Level : Early Advanced

Objective(s):
TSW predict which of three chemicals cause a chemical reaction to produce heat using information from a previous investigation.

TSW investigate why heat is released during a chemical reaction by testing two out of three possible chemicals.

TSW conclude what chemical combination causes the reaction to produce heat using investigation data.

Evaluation:
Learning will be determined as the teacher navigates among the group activities to inquire about the variable chosen to be omitted during the current investigation. Learning will also be assessed as the students recall what happened during their test observation. After the small group investigations are concluded, the class will assemble as whole group to discuss what they had observed.

Pre-requisite Knowledge:
Classroom Safety Rules:
-no smelling or touching chemicals directly
-prevent chemical cross contamination unless otherwise permitted.

Scientific Terms for Chemical Reaction:

*Reactants- chemicals that take part in a chemical reaction.

*Product- the new substance that form during a chemical reaction.

*Exothermic reaction- heat energy is released.

*Endothermic reaction- heat energy is absorbed. (Endothermic reactions feel cool because heat energy from your hand is absorbed by the reaction.)

Terms to Clarify:
Variables:
-The independent variable is the variable you purposely manipulate (change).
-The dependent variable is the variable(s) that is being observed, which changes in response to the independent variable.
-The variables that are not changed are called controlled variables.

Materials:

Materials and resources:
For the class:

Teaching Procedures

Opening (Set):
Yesterday we experienced the exciting observation of a chemical reactions using all the chemicals listed on the board. Today, I challenge you to find out which of the reactants actually caused the reaction to get HOT. By combining the chemicals you see on the board in different ways, you will encounter a range of different reactions. Some groups will experience temperature differences, color differences, and differences in gas production.

Guiding Questions:
Think about what steps we took to cause the combination of chemicals to react. What chemical do you think caused it to produce heat?

Do you think it is the Phenol Red or just the water? Remember, water is mixed in with the Phenol Red powder!

So if the reaction got hot without (whatever chemical they choose), we would know that (chemical) was not a vital contributor of producing heat?

Does your investigation plan relate to the purpose of the experiment: What causes the heat?

Instructional Input:
*Opening: "Yesterday we experienced the exciting observation of a chemical reactions using all the chemicals listed on the board. Today, I challenge you to find out which of the reactants actually caused the reaction to get HOT. By combining the chemicals you see on the board in different ways, you will encounter a range of different reactions. Some groups will experience temperature differences, color differences, and differences in gas production."

*Explain that since phenol red solution was prepared by mixing phenol red powder and water, they should consider both phenol red and water as separate reactants.

*Have students predict which of the reactants they think caused the reaction to get HOT. Have them write them on their paper as the teacher records them on the chalk board.

*Think- pair- share to describe experiments that might determine which reactants are responsible for the production of heat.
Have the groups share suggestions on possible ways to form an experiment. Each suggestion, ask the class how that experiment would provide useful information... based off of their prior knowledge observed from previous investigation.
"So if the reaction got hot without (whatever chemical they choose), we would know that (chemical) was not a vital contributor of producing heat?"

*Reinforce experimental plans that investigate one variable at a time, and help students relate their plans to the purpose of the experiment: WHAT CAUSES THE HEAT?

*Challenge each group to design and conduct two experiments to find out what causes the heat.
...........DO NOT SEAL THE BAGS.........................

*Directions for Heat Experiment:
-design your first experiment, and write what you plan to do on the experiment worksheet.
-before you begin you experiment, explain it to the teacher. Once you have done so, proceed with your experiment.
-Record the results of the first experiment using at least five (5) descriptive words.
-Show the teacher your data before proceeding onto the second phase of your investigation. The teacher will give you a clean vial for the second test.

*Encourage students to circulate around the classroom when they finish, observing the results of other groups' experiments.

*As students share their results, ask if they've narrowed the possibilities of what causes the heat and, if so, WHAT IS THEIR EVIDENCE.
-What experiment could they do to narrow it down even further?

*COLLECT bags and vials in a bucket. Have the students place the materials on their tray and gather for whole group discussion. (Preferably at their desks.)

*Ask the class which group may have discovered the chemicals responsible for the chemical reaction. Poll the group for their opinions.

*Procedure to collect evidence to support or refute the various opinions:
-Ask one group to describe an experiment they did and whether or not the bag got hot.
-Poll other groups to see if those that did the same experiment got similar results.
-Translate responses such as "I mixed everything except baking soda and it still got hot," to an equation form and write it on the chalkboard:
CaCl 2 + phenol red = hot
-After recording the results of different experiments, ask the students which reactants were used in every experiment that got hot.

*Help the class summarize the results be asking: "So, what chemicals are necessary to produce the heat in this chemical reaction?"

****IMPORTANT*****
Ask how people can do the same experiment and come up with different results.
Ask what scientist do when they can't agree on a result.
If time remains, redo the experiment in front of the room. If not, majority rules!

*Select two students to clear the tables and rinse the vials in the sink. MAKE SURE THE STUDENTS ARE WEARING RUBBER GLOVES. The bags can be discarded.

Check for Understanding:
Student understanding will be apparent as they conduct their observations and investigations. Their objective is to determine what chemicals from the previous investigation cause the chemical reaction to produce heat. Understanding will be evident in the structure of their personal investigation plans and reasoning of why they chose the particular chemicals. During the whole group discussion, the students will report the information they observed and share ideas.

Guided (Supervised) Practice:
The students will be in groups of 2-4 conducting personally structure investigations of which chemicals cause the reaction to produce heat. The students are virtually practicing inquiry with little supervision as they find meaning and reasoning in a the combinations they investigate.

Extended (Independent) Practice:

Lesson Closure:
Help the class summarize the results be asking: "So, what chemicals are necessary to produce the heat in this chemical reaction?"

Further explanation:

-Calcium chloride, baking soda, and liquid combine to produce carbon dioxide.

-CALCIUM CHLORIDE AND WATER produce heat.

-PHENOL RED is an acid/base indicator; it changed the color in the presence of acids and bases. BAKING SODA is a base so it maintains the bright color of phenol red at first. As acidic products form, the phenol red changes color from bright pink to orange to yellow. CARBON DIOXIDE gas is one of the acidic products formed. If the gas is allowed to escape, the liquids may turn slightly orange or pink again.

Some of the products in this reaction include:
Sodium Chloride (NaCl): table salt
Calcium carbonate (CaCO 3): the main component of chalk.
Carbon Dioxide (CO 2): one of the gases we exhale