Acids:BasesLab2024

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Feb 20, 2024

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Neutralization of Acids and Bases Ulani Rizo January 24, 2024

Ulani Rizo Neutraliza/on of Acids and Bases Page of 2 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.

Ulani Rizo Neutraliza/on of Acids and Bases Page of 3 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 8 B3 7 B4 7 Picture of pH Paper C pH: ___5___ B5 6

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Ulani Rizo Neutraliza/on of Acids and Bases Page of 4 8 B6 6 Table 1: pH Measurements Trial pH Picture of pH Test Strip B1 – B6 (for Beaker B) Ph paper A Ph paper B1 Ph paper C above / B3 below Ph paper B2 above / B4 below Caption

Ulani Rizo Neutraliza/on of Acids and Bases Page of 5 8 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!). 4. Why should one add acid to water rather than add water to acid when preparing solutions? ( Describe in 1-2 sentences ) I believe that the solution in beaker B was neutralized at B4. This is when the Ph was most neutral. At this point in the experiment the Ph of the solution was 7. Adding acid to water is safer than adding water to acid because the reaction between water and concentrated acid is highly exothermic. Adding acid slowly to water allows for better control and reduces the risk of splattering or overheating, ensuring a safer preparation of solutions. Ph paper B5 Ph paper B6

Ulani Rizo Neutraliza/on of Acids and Bases Page of 6 8 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. 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. 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 . You would need to neutralize a chemical before discarding it down a drain if it is a corrosive or acidic substance that could potentially harm the plumbing or the environment. Neutralization involves adding a base to an acidic solution or an acid to a basic solution to achieve a pH close to neutral, making the waste less harmful before disposal. This helps prevent damage to the drainage system and ensures compliance with environmental regulations.

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Ulani Rizo Neutraliza/on of Acids and Bases Page of 7 8 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 + Based on your answer to Part (d), what is the mole ratio of acetic acid to sodium bicarbonate? 22.99g/mol+1.01g/mol+12.01g/mol+16.00(3)g/mol= 84.01 g/mol 0.50 grams 0.50g/84.01 g/mol = 5.95x10^-3 mol sodium bicarbonate → N a H C O 3 ( a q ) + C H 3 C O O H ( a q ) → C H 3 C O O N a ( a q ) + H 2 O ( l ) + C O 2 ( g )

Ulani Rizo Neutraliza/on of Acids and Bases Page of 8 8 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. 1:1 Since the mole ratio is 1:1 5.95 X10^-3 moles of Sodium bicarbonate will be neutralized by 5.95X10^-3 moles of acetic acid. A weaker solution of sodium bicarbonate will have less sodium bicarbonate molecules in the solution. So according to the neutralize reaction, it will require less acetic acid to neutralize. In the instance that I spill a small amount of HCL acid on the ground I would first make sure I am wearing proper PPE and then neutralize it with a Weak base such as sodium bicarbonate. And then clean it up with an absorbent material and dispose of it in a hazardous waste container.