Peppery Properties of Matter Labs

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Objective

Students will be able to identify the chemical and physical properties of substances.

Big Idea

Students go through a series of fun lab rotations that allow students to look at the chemical and physical properties of substances!

Introduction and Connection to the NGSS and Common Core

In this two day lab rotation, students identify physical and chemical properties independently and go through a series of fun and exciting lab stations in which they must identify properties and how they are affected by thermal energy.

This lesson is designed to address the following NGSS and Common Core standards:

MS-PS1-2  Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.

MS-PS1-4  Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed.  

CCSS.ELA-LITERACY.WHST.6-8.1.B  Support claim(s) with logical reasoning and relevant, accurate data and evidence that demonstrate an understanding of the topic or text, using credible sources.

CCSS.ELA-LITERACY.RST.6-8.4  Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 6-8 texts and topics.

CCSS.ELA-LITERACY.RST.6-8.10  By the end of grade 8, read and comprehend science/technical texts in the grades 6-8 text complexity band independently and proficiently.

Science and Engineering Practices:

When using the text strategies utilized in this lesson, students think deeply about text in order to make their own conclusions and consider solutions to problems.  Thus, students are using the Science Practice of Generating Questions and Designing Solutions which states that, "Students at any grade level should be able to ask questions of each other about the texts they read, the features of the phenomena they observe, and the conclusions they draw from their models or scientific investigations. For engineering, they should ask questions to define the problem to be solved and to elicit ideas that lead to the constraints and specifications for its solution." (SP1

In preparation for performing the lab stations, students use strategies to obtain scientific information and evidence from text (SP7).  In addition, students back up their explanations in the lab document with evidence from data and qualitative observations (SP8).

Crosscutting Concepts:

In identifying properties that may change in the reactions occurring at the lab stations, students can begin to see patterns in the structures of different types of matter and how properties respond to changes in thermal energy.  Thus, students can begin to see that macroscopic patterns are related to the nature of microscopic and atomic-level structure (CCC Patterns).

Connecting to the Essential Question: What are you going to learn today?

5 minutes

Ask students, "What are you going to learn today?".  Students should respond by saying that they will be answering the Essential Question, "How do particles combine into new stubstances? And, what evidence can show how the physical and chemical properties of the substances change?"  This EQ is posted on my board and on the student's Chemistry Unit Plan.  

Explain that today we are going to go through a series of lab stations that will ask them to use their learning from the first three skills.  However, the focus of this lesson is to introduce them to Skill 4, "I can identify the physical and chemical properties of the reactants and products in a reaction."  (It is important to note that my students have already been introduced to physical and chemical properties before this lab.  The notes sheet along with some true/false statements relating these notes along with the answer key is included in the resources.)

As students went through a series of lab stations in the previous lesson, ask students to change their mastery score on their Chemistry Unit Plan if they feel it is necessary.  Notice in the picture below that the student has self-assessed on all skills and adjusted her mastery score (on a scale of 1 - 4, with 4 being mastery).   For a look into what students completed in the previous set of lab stations in which they were introduced to physical and chemical properties, check out this Crack That Marble! Lesson.

Liquid Molecules Lab Rotation

45 minutes

Explain to students that they will be going through a series of lab stations that will ask them to look at the physical and chemical properties of substances going through reactions.  I always ask them to "channel their inner scientist" and thoroughly read the procedures as well as look back at the text (Skill CH.4 Notes Page and True False Statements) to look up and obtain any information they need to answer the lab questions.  I have students rotate through the stations at their own pace in groups of 3 - 5.  My students are used to lab rotations as we use them every week; if this is your student's first experience, you may want to rotate them yourself to make sure they manage their time efficiently.

**It is important for you to note that my students have gone through this Ladder of Discourse Mini Lesson using the Skill 4 Notes page in the resource section.  Understanding this text is essential to students completing this lab rotation independently.

 

How does temperature affect the speed of molecules?

  1. Put on your goggles and safely light the Bunsen burner under the ring stand.
  2. Set a beaker containing 100 ml of water on the stand.
  3. Heat the water to a temperature of 50 degrees Celcius.
  4. Into another beaker, pour 100 ml cold water from the tap and add ice cubes.  Remove the ice cubes after approximately one minute.
  5. Add ONE drop of food coloring to each beaker and observe the different rates of dissolving.

Teacher Tips:  Emphasize one drop of food coloring.  If students place more than one drop in, it can skew the results.  Also, the ice cubes will interfere with the dissolving of the cold water.  Make sure that the cold water is very cold, but that the ice cubes have been removed from the water.  This will allow for a very obvious display of the different rates of dissolving as shown in the picture.

 

Is hot water less dense than cold water?

  1. Using tongs, remove one of the “hot balloons” from the water on the hot plate.
  2. Take a “cold balloon” from the bucket of ice.
  3. Put both of the balloons in the bucket of room temperature water.

Teacher Tips:  The hardest part about this lab is getting the cold balloon to its densest point that it will sink.  Placing warm water in the bucket works best to aid with this.  Emphasize to the students that after dropping the balloons in the water that they should not leave them in the bucket when they rotate.  It is important that the balloons get back into the hot and cold containers so that they can maintain their temperatures.

Making Thermometers

  1. Wrap your hands around the thermometer.  Keep them tight around as much of the thermometer as you can.  Watch the water in the straw.
  2. Once the liquid has reached the top of the straw, remove your hands, place the bottle in the ice water bucket, and watch the water in the straw.

Teacher Tips:  Snapple bottles work really well for creating these; however, I have made them with flasks before.  Add food coloring to water and wrap clay around a straw.  Make a seal with the clay and push the clay down until you see the water rise a little in the straw and not "fall" back down.  When heated, the water should move up the straw all the way to the top!  It takes a minute to warm these up if using your hands.  I have in the past used a hot pan of water or a Bunsen burner to speed the process.  If you do this, just be careful of the Snapple bottle shattering at the bottom if goes from hot to very cold.

Adventures with Pepper 

  1. Fill a beaker with 200 ml of water.
  2. Shake some pepper on the surface of the water.  Do not shake or stir the liquid!  The pepper should be floating on top of the water.
  3. Dip the toothpick in the dish soap, and carefully touch it to the center of the surface of the water.  Enjoy your adventures with pepper!

Crazy Colloid

Experiment with the “Crazy Colloid” to determine the properties that could help classify whether the substance is a solid or a liquid.  "Crazy Colloid" is simply a mix of corn starch and water.  I find that it is best if I mix it for each group.  It is important to get the right consistency.  When I mix it I add about a quarter cup of corn starch and mix in about an equal part of water.  Honestly, I just eye ball it.  I add water slowly until I can do the "Quick Poke Test" and "Slow Poke Test" below.  If I get it too watery, I just add a little more corn starch.  If it is to powdery or solid, I add more water.  Here are some tests you should perform:

1.  Quick Poke Test – Poke your finger quickly in the liquid.

2.  Slow Poke Test – Poke your finger slowly through the liquid.

3.  Pour Test – Pour the substance on the counter.

4.  Shape Test – Try to form the substance into a ball.

5.  Bounce Test – Try to bounce the ball.

The more students "play" with the crazy colloid, the dryer it will get.  To bring it back to life, simply add a tiny bit of water.  A little water goes a long way to revive it!  

Are you thinking...."My students did this in elementary already?"  Whether your students have used this before in elementary school or not, they love it.  And, this will be the first time they used this mixture to discuss properties of matter so the discussions surrounding it will be brand new.

This is a messy experiment that requires some clean up and help from your students.  But, it's worth it....it's all in the name of science!

Liquid Molecule Lab: A Look at Student Work

In this video, I take a look at how students cite evidence in two of the lab questions.  The complete answer key is included in the previous section; this video will give you some insight into how students cite evidence from the labs in their responses.

Closure: Formative Assessment Chemical and Physical Properties

5 minutes

As an Exit Ticket, have students complete this formative assessment.

As I assess these, I sort them into piles of learners with similar needs so that I can meet with them in an upcoming lesson and provide them with re-teaching/clarification.  For example, I often have groups of students that are strong in physical properties, but need more exposure to chemical properties.  I often also have a group that doesn't realize that each substance has it's own unique set of properties and if a new substance is produced, it will have different properties than the reactants.

When I provide feedback on this lab and formative assessment in conference groups, students plot their score and then in the open area on the bottom, they add to their "Working Towards Mastery List".  The "Working Towards Mastery List" is a place students write the concepts or topics that they have not yet mastered or need to study more in depth.  It is a way for each individual student to organize their specific feedback.  Come summative assessment time, students have a clear record of not only their growth, but of the specific concepts that they missed along the way that should be the focus of their studies.

In my class, I score everything as a 1, 2, 3, or 4 (4 being mastery); thus, the y axis is labeled with these scores.  However, you could place your own grading scale that represents your classroom.  In addition, along the x axis, it is labeled "a, b, c, d, etc".  In my gradebook, in order to organize all of my formative assessments in chronological order by skill, I have to include these. You might include assignment names or any other numbering system that would indicate time progression on the x axis.