Vernier Software & Technology

# Reaction Stoichiometry

## Introduction

Stoichiometry is the study of quantitative relationships in chemical reactions. A balanced chemical reaction equation gives the mole ratios of the reactants and the products as coefficients. When some of the chemical formulas are not known, an experiment can be conducted to help determine the mole ratios.

Acetic acid (HC2H3O2) and sodium hydroxide (NaOH) are the reactants in the acid-base reaction to be investigated in the Preliminary Activity. Sodium hydroxide neutralizes acetic acid according to the unbalanced and incomplete equation:

$A{\text{ H}}{{\text{C}}_{\text{2}}}{{\text{H}}_{\text{3}}}{{\text{O}}_{\text{2}}}{\text{ + }}B{\text{ NaOH}} \to {\text{products}}$

It is possible to identify the coefficients of the reactants without knowing the products of the reaction. The process that you will use to determine the coefficients is called continuous variations. You will prepare a series of mixtures of the two reactants. Each mixture will have the same total volume and the same total number of moles of reactants. The reaction is exothermic, thus the mixture that generates the most heat energy will be the reaction that completely consumes both the reactants. You will use this mixture to establish the coefficients, and therefore the mole ratio of the reactants, for the reaction.

## Objectives

In the Preliminary Activity, you will gain experience using a Temperature Probe, data-collection software, and the continuous variations method as you determine the sodium hydroxide to acetic acid mole ratio in the chemical equation for the reaction between sodium hydroxide and acetic acid.

After completing the Preliminary Activity, you will first use reference sources to find out more about acid-base reactions, balanced equations, and mole ratios before you choose and investigate a researchable question that utilizes the continuous variations method to determine the mole ratio of reactants in an acid-base reaction.

## Sensors and Equipment

This investigation features the following Vernier sensors and equipment.

### Option 2

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

## Investigating Chemistry through Inquiry

See other experiments from the lab book.

 1 Physical Properties of Water 2 Baking Soda and Vinegar Investigations 3 An Investigation of Urea-Containing Cold Packs 4 Conductivity of Aqueous Solutions 5 Identifying a Pure Substance 6 Investigating the Energy Content of Foods 7 Investigating the Energy Content of Fuels 8 Evaporation and Intermolecular Attractions 9 Enthalpy Changes 10 Reaction Stoichiometry 11 Beer's Law Investigations 12 Colligative Properties of Solutions 13 Long Term Water Monitoring 14 Vapor Pressure and Heat of Vaporization Investigations 15 Acid-Base Properties of Household Products 16 The Effect of Acid Deposition on Aqueous Systems 17 Acid-Base Titrations 18 Conductimetric Titrations 19 Oxidation-Reduction Titrations 20 Investigating Voltaic Cells 21 Baking Soda and Vinegar Investigations Revisited 22 Reaction Rates 23 Enzyme Activity 24 Sugar Fermentation by Yeast 25 Nuclear Radiation

### Investigation 10 from Investigating Chemistry through Inquiry Lab Book

#### Included in the Lab Book

Vernier lab books include word-processing files of the student instructions, essential teacher information, suggested answers, sample data and graphs, and more.