IB Chemistry SL Stochiometry IA

Topics: Hydrochloric acid, Pipette, Chemical reaction Pages: 24 (2944 words) Published: January 30, 2014
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Determining Stoichiometric Ratios:
NaOH and HCl & NaOH and H2SO4 Reactions

Contents

Introduction

3
Materials & Procedure

4
Raw Data

8
Processed Data

15
Graphs

16
Conclusion & Evaluation

17

Introduction

Background Information
Stoichiometry is a critical component in chemistry, and helps in understanding the quantitative relationship between the number of moles of reactants and products in a reaction.

Objective
In this experiment, the reactions between sodium hydroxide and hydrochloric acid, and sodium hydroxide and sulfuric acid will be studied.

Beginning Questions
When will the maximum extent of the reaction occur? Which will the limiting reagent? Which of the two acid-base combinations will absorb/liberate the greatest amount of heat energy?

Hypothesis
When NaOH and HCl are mixed, the maximum extent of the reaction should occur approximately when the amount of acid is slightly higher than the base. HCl will be the limiting reagent. When NaOH and H2SO4 are mixed, the maximum extent of the reaction should occur approximately when the amount of base is slightly higher than the acid. NaOH will be the limiting reagent. Of the two combinations, the reaction between NaOH and H2SO4 will likely absorb/release the greatest amount of heat energy, because the mole ratio is 2:1, whereas the mole ratio of NaOH and HCl is 1:1.

Variables
The amount of each reagent in acid-base reactions will be systematically varied between the trials, and will total 50 mL when combined. One of the two reagents will begin at 45 mL, and the other at 5 mL. The former will decrease in increments of 5 mL while the latter increases in increments of 5 mL. The independent variable is the varying measurements of reactant, while the dependent variable is the temperature change as result of the reaction taking place. It is crucial that the molarity of the acid and base remain constant.

Materials & Procedure

Materials

10 mL graduated cylinder
25 mL graduated cylinder
50 mL graduated cylinder
1 mL volumetric pipet
3 mL volumetric pipet
5 mL volumetric pipet
10 mL volumetric pipet
50 mL volumetric pipet
100 mL volumetric pipet
Pipet bulb
500 mL volumetric flask
1000 mL volumetric flask
250 mL, 1000 mL beakers
Thermometer
Plastic foam cup
Balance
3.0 M solutions of HCl, H2SO4, and NaOH
Parafilm
Distilled water

Safety Considerations

Safety goggles should be worn to prevent any of the chemicals from accidentally reaching the eyes. Closed-toe shoes are necessary for any potential lab-related accidents. Refrain from eating or drinking in the lab area; food or drinks can be contaminated. Gloves are not necessary for handling NaOH and HCl, but if any skin is to come into contact with the chemicals, it should be washed quickly with soap and water. Gloves and an apron are necessary when handling H2SO4; this acid will burn through clothes and skin, so it is advised to take precaution when handling H2SO4. H2SO4, in large quantities, should be used under a fume hood. If any H2SO4 is spilled, check yourself. Any contaminated material should be immediately removed, and exposed skin or eyes should be washed for at least fifteen minutes. Once you have checked yourself, evaluate the spill amount. If there is a large pool, a hazardous materials team should be called in and evacuate the area; the fumes can be fatal.

If the amount of H2SO4 is small enough, NaHCO3 (baking soda) or soda ash can be thrown on the acid to neutralize it. The remains should be swept up, and the area washed multiple times with water and more NaHCO3.

Procedure: Reaction Between NaOH and HCl

1. Gather all materials.
2. Prepare 500.00 mL of 1.0 M HCl from the 3.0 M solution available in the appropriate volumetric flask, and prepare 500.00 mL of 1.0 M NaOH from the 3.0 M solution available in the appropriate volumetric flask 3. Stir the solutions vigorously for a...

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