Lab 8 PreLab

INTRODUCTION

Chemical reactions can be classified into 5 basic types:

  1. Combination (CA)
  2. Decomposition (D)
  3. Combustion (CU)
  4. Double Replacement – precipitation, neutralization (DR)
  5. Single Replacement (SR)

General patterns associated with the reactants and/or products can be used to help the chemist identify reaction types.  This laboratory experiment will focus on the identification/classification of several reactions based on observation of the reactions themselves and inspection of the reaction equations.

SAMPLE DATA

Below is a list of patterns associated with each type of reaction equation and the resulting observations one would expect to see when viewing the reactions.

Type Reaction/Products Observations
Combination Only 1 product species —-
Decomposition Only 1 reactant species Changes in a solid reactantwhen heated
Combustion CO2(g) & H2O(g) are products; O2(g) is reactant Flame occurs
Double Replacement – precipitation One product is an ionic solid; both reactants are ionic solutions Precipitate forms
Double Replacement – neutralization One product is water and another product may be CO2(g); reactants are an acid and a base Heat is produced in most reactions; if CO2(g) is a product, bubbles will appear
Single Replacement One product is a metal solid; one reactant is a different metal solid

-or-

One reactant is a metal solid and the other reactant is an acid

Solid reactant metal disappears and a different solid metal (product) appears-or-

Solid metal reactant disappears and gas bubbles will appear

The above information can help you determine the type of reaction under investigation.

For example, consider the reaction illustrated below:

3BaCl2(aq) + 2Na3PO4(aq) à Ba3(PO4)2(s) + 6NaCl(aq)

Upon inspection of the equation, the fact that 2 ionic solution are used as the reagents may lead one to type the reaction as Double Replacement – precipitation.  Confirmation of the reaction type would involve observing the formation of a solid precipitate during the reaction process.  Therefore, both observations of actual reaction processes and pattern recognition of reaction equations are used to classify reactions.

OBJECTIVES

There are three objectives for this experiment:

  1. Perform each reaction and record observations
  2. Balance each reaction equation
  3. Classify each reaction type

ORIENTATION

This exercise will require the use of the following glassware and hardware:

  1. Test Tubes (small)
  2. Graduated Cylinders (10 mL)
  3. Stirring Rods
  4. Evaporating Dish
  5. Splints/Matches
  6. Bunsen Burner
  7. Well Plates

This exercise will use the following chemicals:

Solutions

  1. .1M CaCl2
  2. .1M Na3PO4
  3. .1M Na2CO3
  4. .1M CuSO4
  5. 1M Na2CO3
  6. 6M HCl
  7. 3M HCl
  8. 1M HCl
  9. 3M H2SO4
  10. 3M NaOH
  11. 3% H2O2
  12. Saturated Ca(C2H3O2)2
  13. C2H5OH

Solids

  1. Cu(OH)2
  2. CuSO4.5H2O
  3. NaI
  4. Zn
  5. Mg (turnings)
  6. CuSO4
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