AshleyHensley_03_AcidsBases_PostLab

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Arizona State University, Tempe *

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Chemistry

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Feb 20, 2024

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Neutralization of Acids and Bases Ashley Hensley 01/20/2024 TOTAL: 20 points

Insert Name Neutralization of Acids and Bases Page 2 of 8 CHM 113 POST-LAB Neutralization of Acids and Bases 1. Insert ONE picture of yourself in full PPE here ( include the pH test strip key in your PPE picture ). **Remember to (1) show your full body so that we see you are wearing shoes; (2) wear your safety glasses, full sleeved clothes, and gloves; (3) cover your arms, lower legs and ankles (socks are required, even in Arizona); (4) tie back long hair in a ponytail or a bun; (5) remove jewelry.

Insert Name Neutralization of Acids and Bases Page 3 of 8 2. Enter your data for your pH measurements of the neutralization of sodium bicarbonate (Table 1) below. NOTE: Your table should contain pH values and pictures of pH test strips for “A,” “C” and six trials with beaker “B.” Please include the pH Test Strip Key in your photos for comparison. If you needed to repeat this experiment or for any other reason you used pH test strips purchased from another source (other than eScience), you MUST provide the pH test strip key below the table. Table 1: pH Measurements Trial pH Picture of pH Test Strip B1 – B6 (for Beaker B) B1 9 Picture of pH Paper A pH: ___7___ B2 9 B3 8

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Insert Name Neutralization of Acids and Bases Page 4 of 8 Table 1: pH Measurements Trial pH Picture of pH Test Strip B1 – B6 (for Beaker B) B4 8 Picture of pH Paper C pH: ___5___ B5 7 B6 7 3. At what point was the solution in beaker “B” neutralized? Use data from Table 1 to support your statement in 2-3 sentences. Note: If the solution in beaker “B” was not neutralized, explain the potential source of error (“Human error” is NOT an acceptable source of error— be specific!).

Insert Name Neutralization of Acids and Bases Page 5 of 8 The point of the solution in beaker “B” at which it became neutralized as at I believe B5, if I am reading the colored strips accurately. Also, in comparison to strip A, it looked identical, as A was the neutral distilled water. 4. Why should one add acid to water rather than add water to acid when preparing solutions? ( Describe in 1-2 sentences ) Adding water to acid when preparing solutions can cause a heat reaction that will result in splashing and could get on the skin and in the eyes. To prevent such reaction, is why you should always add acid to water. 5. Most of the chemicals included in your General Chemistry Lab kit can be discarded down a drain. Describe a situation (in 2-3 sentences) in which you would need to neutralize a chemical before discarding it down a drain. Chemicals that are strong acids/bases have the potential to cause corrosion, so it would not be a good idea to discard anything down a drain without making sure it is neutralized. Hydrochloric acid (HCl) is an example of a strong acid that can cause such corrosion. 6. Match. Choose the best answer for each of the following. __C__ acid A. A logarithmic scale (0 – 14) used to specify the acidity/basicity of a solution. ___B_ water B. An example of a neutral solution (pH is approximately 7) __D__ NaHCO 3 solution C. A substance that is able to donate a proton (H + ) which increases the [ H + ] when it dissolves in water. _F___ base D. An example of a basic solution (pH > 7) __A__ pH E. An example of an acidic solution (pH < 7) __E__ acetic solution F. A substance that is able to accept a proton (H + ) which increases the [ OH - ] when it dissolves in water.

Insert Name Neutralization of Acids and Bases Page 6 of 8 7. Solve. HINT: For guidance in answering the following questions, please refer to the Tutorial for Week 3 Problem Solving available in the Week 3 Post-Lab module. a. What is the molar mass of sodium bicarbonate, NaHCO 3 ? Show your work and include units . b. How many grams of sodium bicarbonate, NaHCO 3 were present in Beaker “B” in Trial 1 ( this was before any acid was added )? c. Based on your answers to Parts (a) and (b), how many moles of sodium bicarbonate were present in Beaker “B” in Trial 1 ( this was before any acid was added )? Show your work and include units. d. What is the balanced molecular equation for the neutralization reaction between acetic acid and sodium bicarbonate (these are the reactants)? Include correct formulas, coefficients and physical states. HINT: One product of this reaction is carbonic acid (H 2 CO 3 ) which is highly unstable and immediately decomposes into carbon dioxide and water. HINT: A similar reaction with a different acid can be seen in the Tutorial for Week 3 Problem Solving available in the Week 3 Post-Lab module. You will replace HCl with CH 3 COOH in the reaction. HINT: Acetic acid loses the last H in the formula: CH 3 COOH → CH 3 COO - + H + Na – 22.989770 H – 1.00794 C – 12.0107 O3 – 15.9994*3 + 84.00661 rounded to 84.01 g/mol 0.5 grams 0.5 g * 1 mol = 0.005951 rounded to 5.95*10^-3 mol NaHCO3 84.01 g CH3COOH (aq) + NaHCO3 (aq) → CH3COONa (aq) + H2CO3 (aq) H2CO3 (aq) → CO2 (g) + H2O (l) – This happens due to instability of H2CO3

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Insert Name Neutralization of Acids and Bases Page 7 of 8 e. Based on your answer to Part (d), what is the mole ratio of acetic acid to sodium bicarbonate? f. Based on your answer to Part (e), calculate the number of moles of acetic acid that are required to neutralize all of the sodium bicarbonate. Show your work and include units. g. Based on your answers to Parts (a – f), if a weaker solution of sodium bicarbonate was used in beaker “B,” would it require more or less acetic acid to neutralize? Explain why in 2-3 sentences . 8. Putting it all together! Based on your results from this lab, propose a plan (in 2 – 3 sentences) to address how you would handle SAFELY cleaning up a small chemical spill on the ground involving hydrochloric acid (HCl). HCl is also known as muriatic acid and is often used in pool maintenance. 1 CH3COOH (aq) + 1 NaHCO3 (aq) → 1 CH3COONa (aq) + 1 H2CO3 (aq) Mole Ratio 1:1 1 mol CH3COOH (aq) * 1 mol NaHCO3 (aq) = 1 mole CH3COOH I believe that it would require less acetic acid to neutralize a weaker solution of sodium bicarbonate, because if there were a lower ratio of a substance, it would take less of a neutralizer to balance it out. To safely clean up a chemical spill of HCL, I would first look up in the SDS to see which base can be used to neutralize it. After that I would slowly add the base to neutralize HCL. Once the pH is at neutral 7, I would clean it up with something that is disposable (paper towel if it is still somewhat aqueous, broom/dustpan if possible) and dispose of it in a trash bin. After I would thoroughly wash the area, and my hands with soap and water.

Insert Name Neutralization of Acids and Bases Page 8 of 8