The Law of Conservation of Matter

Objectives

  • Explain the Law of Conservation of Matter and how it can be verified.
  • Determine if a chemical reaction has occurred.
  • Identify sources of error and explain their impact on experimental data.
  • Write formulas for named compounds and named compounds from written formulas.
  • Write and interpret balanced chemical reactions.
  • Determine the solubility of a compound in aqueous solution.
  • Draw conclusions based on experimental data.
  • Apply knowledge of scientific theories to problem-solving applications.

Related Textbook

Please read section 3.7 of your textbook before beginning this activity. The textbook provides terms, concepts, and other important background information to help you complete this assignment.

Introduction

The Law of Conversation of Matter (or Conservation of Mass) states that matter is neither created nor destroyed.  In other words, the amount of matter present at the start of a reaction should be the same as the amount of matter present once the reaction is complete.  If the mass is conserved during a chemical reaction, then the total mass of the reactants should equal the total mass of the products. Video 1.0 discusses the Law of Conservation of Matter.

In this week’s lab, you will experimentally determine if the Law of Conservation of Matter is valid. You will collect your data and calculate the percent change in mass for each trial. The formula for these calculations is provided on the data table linked below.

NOTE: You are looking to see if the mass stays the same from start to finish in Trial 1 and from start to finish in Trial 2.  It does not matter if the mass in Trial 1 differs from that in Trial 2.  What matter is if the mass stays the same throughout the same trial.

You will organize your data for this lab into a data table. Click below for a copy of the data table you will need for this lab. It will download to your computer. If you have trouble downloading it, check to ensure blockers are disabled.

The Law of Conservation of Matter Data Table

Video 1.0 – The Law of Conservation of Matter (1)

Experimental Procedure

Chemicals and Supplies

Digital balance

Digital Thermometer

two balloons

Acetic acid (vinegar), HC2H3O2

Sodium bicarbonate (baking soda), NaHCO3

two 16 or 20oz plastic soda or water bottles

two balloons

Paper cupcake liners (weigh boats)

50mL graduated cylinder

Spatula

Funnel

  1. Obtain approximately 3g of sodium bicarbonate. Record the exact amount used on the DATA TABLE.

NOTE: To properly measure this amount of sodium bicarbonate, place a weigh boat on the digital balance and “TARE” the balance according to the directions provided with your balance.  This tells the balance to ignore the mass of the weigh boat and only measure the mass of the chemical.  Next, use a spatula to add 3g of sodium bicarbonate to the weigh boat.

Measuring slightly more or less than 3g of the chemical is okay.  Just be sure to write down exactly how much of the chemical you use.  Write down all the numbers on the balance, even if it’s a zero.  This is true of all of the experiments we will conduct in this course.

  1. Using a funnel, add the sodium bicarbonate to the balloon.
  2. Measure 30mL of acetic acid using the graduated cylinder. Be sure to measure to the meniscus as described in the Physical Properties of Matter experiment.  Record this information on the DATA TABLE.
  3. Measure the temperature of the acetic acid. Record this information on the DATA TABLE.
  4. Add the acetic acid to the bottle.
  5. Carefully attach the balloon to the top of the bottle. DO NOT allow any of the sodium bicarbonate to enter the plastic bottle.  The balloon should hang down off the side of the bottle, holding the sodium bicarbonate.
  6. Obtain the bottle’s mass, balloon, acetic acid, and sodium bicarbonate. Record this information on the DATA TABLE.

Take a photo of the plastic bottle, balloon, and digital balance after Step 7.  A piece of paper that includes your name, CHEM 1000, and the semester you are taking this class (for example, if you take this during the fall semester in 2023, write “Fall 2023” on the paper) should also appear in this photo.  This information must be handwritten, legible, and large enough to be clearly read on the piece of paper.  This assignment will not be graded unless this photo has been included with your submission.

  1. Remove the bottle, balloon, acetic acid, and sodium bicarbonate from the balance. Carefully tip the balloon and allow all of the sodium bicarbonate to fall into the plastic bottle.  Record your observations on the DATA TABLE.

NOTE: It is necessary to perform the next two steps quickly to be able to record an accurate final temperature.

  1. When all evidence of a reaction has ended, place the bottle, balloon, acetic acid, and sodium bicarbonate on the digital balance and determine the total mass. Record the final mass on the DATA TABLE.
  2. As soon as the reaction is complete and you have recorded the final mass, remove the balloon from the bottle and obtain the final temperature of the solution. Record this information on the DATA TABLE.

Take a photo of the plastic bottle, balloon, and digital balance after Step 10.  A piece of paper that includes your name, CHEM 1000, and the semester you are taking this class (for example, if you take this during the fall semester in 2023, write “Fall 2023” on the paper) should also appear in this photo.  This information must be handwritten, legible, and large enough to be clearly read on the piece of paper.  This assignment will not be graded unless this photo has been included with your submission.

  1. Obtain a new balloon and plastic bottle and repeat the entire procedure. Record your data on the data table under “Trial 2.”

Waste Disposal

  • The reacted sodium bicarbonate and acetic acid can be flushed down the drain with lots of tap water.
  • Place the used balloons and plastic bottles in the trash.
  • Wash any other equipment used with soap and water (the final rinse is with DI water) before putting it away.

Assignment

Once you have completed this experiment and recorded all of your data:

  • Upload the photos outlined in the experimental procedure after steps 7 and 10 to the assignment folder provided on Brightspace. You should upload a total of 4 photos to the assignment folder.
  • Use the information you obtained to complete the electronic assignment for this experiment on Brightspace. Since you are completing this assignment electronically, submitting your data table via Brightspace is unnecessary.  The electronic assignment will only open after you have uploaded your photos to the assignment folder for this experiment. This assignment is worth 10 points.

References

(1) Ted-Ed. The law of conservation of mass – Todd Ramsey. [Video]. February 26, 2015. https://youtu.be/2S6e11NBwiw (accessed June 17, 2023).

This page was created on June 17, 2023, and was last updated on August 3, 2023.

© Catherine Haslag 2023. All Rights Reserved.