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Classification of Chemical Reactions...

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LaGuardia Community College SCC201 Fundamentals of Chemistry I

Experiment # 3

CLASSIFICATION OF CHEMICAL REACTIONS

Andreas christoforou

Instructor: Dr. Vance OBJECTIVES To observe five of the common types of chemical reaction and balance the chemical equations.

EXPERIMENTAL MATERIALS            

Distilled water 13 test tubes A test tube block A tong (test tube holder) A Bunsen burner 2 of 100.0 mL graduate cylinders A 250.0 mL graduated cylinder Wax papers Splints An evaporating dish An 125 mL Erlenmeyer Flask A balance

The Chemical:

1.1M CuSO4 0.1 M ZnSO4 ZnSO4.7H2O 0.1 M CaCl2 0.1 M Na3PO4 0.1 M NaNO3 2g of CuSO4.5H2O 3M NaOH 0.5M CuSO4 Cu(OH)2 6M HCl Zn 0.1 M Na2CO3 3M HCl 3% H2O2 0.1 g MnO2 Ca(C2H3O2)2

95% C2H5OH NH4Cl Sr(OH)2.8H2O 3M H2SO4 H3BO3

Copper (II) Sulfate Zinc Sulfate Zinc Sulfate Heptahydrate Calcium Chloride Sodium Phospate Sodium Nitrate Copper Sulfate Pentahydrate Sodium Hydroxide Copper (II) Sulfate Copper (II) Hydroxide Hydrocloric acid Zinc ribbon Sodium Carbonate Hydrocloric acid Hydrogen Peroxide Manganese Dioxide (Catalyst) Calcium Acetate Ethanol Ammonium Chloride Strontium Hydroxide octahydrate Sulfuric acid Boric acid

EXPERIMENTAL METHODS Firstly, all glassware such as test tubes and graduated cylinders were thoroughly washed with soap and rinsed with distilled water. Every acid was labeled and obtained. The acids were measured with the graduated cylinders ( for mL) and the balance (for gram). Classification of reactions: 1. 3.0 mL of 0.1 M CaCl2 was mixed with 2.0 mL of 0.1 M Na3PO 4 in the test tube. 2. 0.5000 g CuSO4 was placed into the test tube and 3-4 drops of distilled water was added to it. 3. 0.5000 g Cu(OH)2 was placed into the test tube and it was heated with a Bunsen burner. 4. 3.0 mL of 6M HCl was placed into the test tube and added a 1 cm2 piece of zinc ribbon. Then, to see the reaction, a lighted splint was inserted into the mouth of the test tube. 5. 2.0 mL of 3M HCl was placed into the test tube and mixed with 2.0 mL of 1M Na2CO3. 6. 3.0 mL of 3% H2O2 was place in the test tube and added with 0.1000 g of MnO2. 7. First, 2.0 mL of a saturated calcium acetate solution was placed into the evaporating dish. Then, 15.0 mL of ethanol was added to the dish and swirled the content. To see the reaction, it was ignited with a match. In addition, the reaction was more complex when some boric acid was sprinkled on the mixture. 8. 7.0000 g of Sr(OH)2.8H2O was placed to the 125 Erlenmeyer flask and 3.0000 g of NH4Cl was added. Then, the mixture was swirled for about 5 minutes. 9. 2.0 mL of 3M H2.SO4 was mixed with 2.0 mL of 3M NaOH in the test tube. 10. 2.0 mL of 0.1 M CaCl2 was mixed with 2.0 mL of 0.1M Na2CO3 in the test tube. 11. 3.0 mL of 0.1M CuSO4 was placed into the test tube and 1 cm2 piece of zinc ribbon was added to it. 12. 3.0 mL of 0.1M ZnSO4 was placed into the test tube and 1 inch long piece of copper wire was added to it. 13. 1.0 mL of 0.1M CaCl2 was mixed with 2.0 mL of 0.1 NaNO3 in the test tube. 14. 2.0000 g of CuSo4.5H2O was heated in the test tube with a Bunsen burner. 15. 2.0 mL of 6M HCl was mixed with 4.0 mL of 3M NaOH in the test tube.

DATA AND CALCULATIONS The data that showed below were determined by the balance equation of reaction, classification, and observation. In addition, the classification of the reaction was symbolized by one or two letters, such combination (CA), decomposition (D), combustion (CU), single replacement (SR), and double replacement (DR).

The result of the experiments: 1. 3 CaCl2 (aq) + 2 Na3PO4 (aq) = 1 Ca3(PO4)2 (s) + 6 NaCl (aq)

(DR)

When CaCl2 was mixed with 2 Na3PO4, the mixture turned in to white color.

2. 1 CuSO4 (s) + 1 H2O (l) = 1 CuSO4.H2O (s)

(CA)

When CuSO4 was mixed with water, the mixture contained light blue precipitates.

3. 1 Cu(OH)2 (s) = 1 CuO (s) + 1 H2O (g)

(D)

Solid of Cu(OH)2 was heated, then black ash was left with a little water.

4. 1 Zn (s) + 2 HCl (aq) = ZnCl2 (aq) +1 H2 (g) 2 H2 (g) + 1 O2 (g) = 2 H2O (g)

(SR) (CA)

When a piece of zinc was added to HCl, there were the bubbles. Then, after several second, there was smoke on the top of the solution; it was because the reaction contained oxidation.

5. 2 HCl (aq) + 1 Na2CO3 (aq) = 2 NaCl (aq) + H2O (l) + CO2 (g)

(DR)

When HCl was added with Na2CO3, the mixture was overflowing. Then, there were bubbles left. It was because the product contained the gas.

6. 2 H2O2 (aq) = 2 H2O (l) + 1 O2 (g)

(D)

When H2O2 was added with the catalyst, it happened that the substance contained the oxygen. Therefore, the reaction of the mixture was bubbles.

7. 1 C2H6O (l) + 3 O2 (g) = 2 CO2 (g) + 3 H2O (g)

(CU)

There was a white precipitate when the ethanol was added to saturated calcium acetate. Then, there was also flame remained in the reactant when it was ignited with a match because the reaction of the reactant contained ethanol and oxygen. In addition, the flame became green color when boric acid was sprinkled to the flame. As the flame had extinguished, white powder was left.

8. 1 Sr(OH)2.8H2O (s) + 2 NH4Cl (s) = 1 SrCl2 (aq) + 2 NH3 (aq) + 10 H2O (l)

(DR)

When the solid of Sr(OH)2.8H2O was mixed and swirled with the solid of NH4Cl, the mixture was kind of melting. Then, the mixture produced a pungent smell. Moreover, the temperature of the reactant was decreasing because it was getting cold.

9. 1 H2SO4 (aq) + 2 NaOH (aq) = 1 Na2SO4 (aq) + 2 H2O (l)

(DR)

When H2SO4 (aq) was added with NaOH, the temperature of mixture was increasing and it was getting hot.

10. 1 CaCl2 (aq) + 1 Na2CO3 = 1 CaCO3 (aq) + 2 NaCl (aq)

(DR)

When CaCl2 was added with 1 Na2CO3, the (clear) color changed into a white color.

11. 1 Zn (s) + 1 CuSO4 (aq) = 1 ZnSO4 (aq) + 1 Zn (s)

(SR)

When a silver zinc ribbon was added to CuSO4, the zinc turned into a black color in solution.

12. 1 Cu (s) + 1 ZnSO4 (aq) = 1 CuSO4 + 1 Zn (s)

(DR)

There was no apparent reaction.

13. 1 CaCl2 (aq) + 2 NaNO3 (aq) = 1 Ca(NO3)2 (aq) + 2 NaCl (aq) There was no apparent reaction.

(DR)

14. 1 CuSO4. 5H2O (s) = 1 CuSO4 (s) + 5 H2O (l)

(D)

CuSO4. 5H2O (s) was originally blue color powder. Then, when it was heated by burner, it turned into white color powder and there was evaporation in that there was a little water in the result of the reaction.

15. 1 HCl (aq) + 1 NaOH (aq) = 1 NaCl (aq) + 1 H2O (l)

(DR)

When HCl was mixed with NaOH the temperature of the mixture was increasing and it became hot / warmer.

DISCUSSION Results Obtained The process of the classification often assisted with the simplification and solution of problems. Hence, classification of chemical reaction was classification of reaction or evidence for chemical change balance equation. A chemical reaction was the process in that a new substance was formed with different properties and characteristic from the original substances. In this experiment, the chemical reactions were classified with five types. Five types of the chemical reaction were combination, decomposition, combustion, single replacement, and double replacement. Combination reactions was when two compounds react to form one compound; decomposition was when one substance broke down into two or more substances; combustion was the rapid reaction of compound with oxygen; single replacement was when the element reacted with a compound to give another compound and element; double replacement was when two elements reacted to give two new compounds. The evidences with the corresponding of the 5 common reactions were color change, formation precipitate, heat change, gas evolution, and new odor formed. For example, the observation of the color change in which the zinc turned into a black color in solution when a silver zinc ribbon was added to CuSO4. A chemical equation was to represent the reactants and products of a chemical reaction. Chemical equation was to balance the reactant and the product. The Law of Conservation of Mass stated that in a chemical reaction no mass was lost or gained. Therefore, the subscripts should not be changed to balance the equation, so there was no loss or gain of the element in a chemical reaction. The material was used by using the coefficient or number in front of formula in order to balance the equation. For example; … C2H6O (l) + … O2 (g) = … CO2 (g) + … H2O (g) The largest subscript was located from the formula and Oxygen was always the last one to balance. Then result of this reaction was 1 C2H6O (l) + 3 O2 (g) = 2 CO2 (g) + 3 H2O (g)

Errors Possible error happened when the substance needed to add without a few drop of water (the range a few drop of water, 2 to 3 drops) , it would interfere with the chemical reaction’s test because when the substance had a small portion, so it also needed to add/ mix with a small portion of water to balance the reaction. Another error, it was important that all glassware were dry from water before we put the substances, because the reactant would contain water, then it

would affected the reaction of the product. Moreover, it was necessary to be aware of, if the mixtures that were really needed to use the heat to get the reactions.

Precautions During the experiment, all glassware were thoroughly washed with soap, and rinsed with distilled water in order to avoid contamination of the solution being tested, and it would also give the accurate presence of the solution. Copper sulfate should be avoided by skin contact because it was corrosive. If the contact occurred, it was needed to wash with copious quantities of water. Before using the chemical reagent and mixed to another, it was needed to check carefully the label. Also, the equipments such as the test tube and the Benson burner that were hot should be aware.

CONCLUSION Based on the tests conducted and observation recorded, it was found that the chemical reactions contained the evidences such as color change, formation precipitate, heat change, gas evolution, and new odor formed. In addition, there was also no apparent reaction for experiment number 12 and 13. It was probably soluble, so there was no product formed. To describe the chemical reaction, a chemical equation was important because chemical equation was to balance between the reactant and the product.

REFERENCES 1. Brown, Theodore L.; LeMay, H. Eugene; Bursten, Bruce E.; Chemistry: The Central Science, 11th Edition, Prentice-Hall, 2008. 2. Miller, Dionne A. (Second Edition.); SCC201 Fundamentals of Chemistry Laboratory Manual; Cengage Learning, 2009, pp 25 – 32. 3. Charpi, Anthony. Chemical Equation. 2003. http://www.visionlearning.com/library/module_viewer.php?mid=56. April 2, 2011. 4. Hamilton, Walter S. the classification of Chemical Reactions. https://chemistry.twu.edu/tutorial/TypeChemRxSum.html. April 1, 2011. ....