Final Review Lab# 1- Acids, Bases, Solutions, and Gases

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Objective

Students will be able to solve problems related to various semester 2 concepts through performing a final review titration and gas lab.

Big Idea

Bases and Acids react together to make a neutral solution and gases expand when heated and compress when cooled.

Introduction

In this lesson students have a chance to review for their final exam while also performing a fun and engaging lab activity where they get to do an acid and base titration and inflate a balloon on and Erlenmeyer Flask with a hot plate.

  • This lesson aligns with NGSS Science and Engineering Practice 3: Planning and Carrying out Investigations because students are performing a lab. 

For this lab activity there are several materials needed.  I provide the following for each lab group:

  • burette
  • burette clamp
  • ring stand
  • 0.1 M NaoH in a labeled bottle
  • 0.1M HCl in a bottle labeled (unknown HCl)
  • 50 mL beaker
  • 125mL ER flask
  • pH meter (or paper)
  • stir plate
  • bromothymol blue
  • glass funnel
  • magnetic stir bar
  • hot plate
  • balloon
  • 250mL beaker for cold water
  • oven mitts

 

Explain

5 minutes

I begin the lesson by passing out the review lab #1 to students. 

I then go over general safety with students including how they should wear their goggles because of the acids/bases, how they should handle the burettes, and how to work with the ER flasks on the hot plate.

I make sure to explain the basics of the burettes to students.  This includes how to open and close the stopcock, how to fill the burette carefully with a funnel, and how to keep a beaker underneath the burette in case it leaks. 

I tell students that the lab is fairly straightforward and that they should be able to figure out how to answer the questions with the help of their partners.   I tell them that if they are stuck as a group they should try their notes first, and if all of them do not get the question, that they should then raise their hands and I will come around to help them.

I then split students into cooperative groups, have them go to their assigned lab stations, and start the lab.  For more details about how I use cooperative groups see my reflection from unit 1

Elaborate

90 minutes

For this section of the lab students are performing their experiments and reviewing semester 2 concepts with the review lab #1.

The first part of the lab involves performing an acid/base titration.  Some of the areas where students are confused include:

  • Setting up the burette with NaOH.  This video shows how students first fill the burette with NaOH using a funnel.   This second video shows how students open the stopcock until the burette shows a reading of 0mL.
  • Adding NaOH to the HCl until it turns exactly green.  This is a picture of what the ER flask should look like at the beginning of the experiment with a yellow color, while this is a picture of what the ER flask should look like at the end of the experiment with a green color.  This video shows students adding NaOH to the HCl until it turns green, while this video shows students adding too much NaOH so the solution turns blue. 
  • Calculating the number of moles of HCl used in the experiment.  This is a problem for students because we have not done it since first semester. This video shows me explaining to students how to figure this out. 

The second part of the lab involves students placing a ballon on an ER flask that has some water in the bottom, heating it up, and then cooling it down.  These are two videos from the lab:

  • In this first video you can see how the balloon inflates on the hot plate.
  • In this second video you can see how the balloon deflates in the cold water. 

When students are done with their labs I have them turn in.  I grade the labs based on level of completion with students who have the lab complete getting a check (100%), those missing several questions a check minus (75%), and those that are missing at least a page worth's of information a check minus minus (50%).  

Because students are doing the lab as a group and I am walking around to make sure that they are on task and answering questions, most part students complete their labs and earn a check.

This is an example of one student's completed lab.

Evaluate

25 minutes

As students complete their labs I have them work on their final exam review.  This is a paper which I give students after the unit 10 exam, so they have well over a week to complete on their own as homework, as well as when we have extra time at the end of class.  I have students turn in the final exam review at the final.  I have copies of the answer key for the review for students to check as they are working on the review and have questions.  

This is a copy of one student's final review.