Endothermic and Exothermic Reactions

Recommended for grades 6–12.

Figure from experiment 5 from Physical Science with Vernier

Introduction

Some chemical reactions absorb energy and are called endothermic reactions. Many chemical reactions give off energy. Chemical reactions that release energy are called exothermic reactions. You will study one endothermic reaction and one exothermic reaction in this experiment.

In Part I, you will study the reaction between citric acid solution and baking soda. An equation for the reaction is

${{\text{H}}_{\text{3}}}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{{\text{O}}_{\text{7}}}{\text{(aq) + 3 NaHC}}{{\text{O}}_{\text{3}}}{\text{(s)}} \to {\text{3 C}}{{\text{O}}_{\text{2}}}{\text{(g) + 3 }}{{\text{H}}_{\text{2}}}{\text{O(l) + N}}{{\text{a}}_{\text{3}}}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{{\text{O}}_{\text{7}}}{\text{(aq)}}$

In Part II, you will study the reaction between magnesium metal and hydrochloric acid. An equation for this reaction is

${\text{Mg(s) + 2 HCl(aq)}} \to {{\text{H}}_{\text{2}}}{\text{(g) + MgC}}{{\text{l}}_{\text{2}}}{\text{(aq)}}$

Objectives

In this experiment, you will

Observe two chemical reactions.
Measure temperature changes.
Determine the change in temperature, Δt, for each of the reactions.
Identify endothermic and exothermic reactions.

Sensors and Equipment

This experiment requires each of the following Vernier sensors and equipment (unless otherwise noted):

Stainless Steel Temperature Probe

Additional Requirements

You may also need an interface and software for data collection. What do I need for data collection?

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The student-version preview includes:

Step-by-step instructions for computer-based data collection
List of materials and equipment

Note: The experiment preview of the computer edition does not include essential teacher information, safety tips, or sample data. Instructions for Logger Pro and other software (such as LabQuest App or TI handheld software, where available) are on the CD that accompanies the book. We strongly recommend that you purchase the book before performing experiments.

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Standards Correlations

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