A student prepared 100.0 mL of a buffer in the lab that contains 0.300 M of a weak acid, HA, and 0.200 M of its conjugate base, NaA. The student then added 1.0x10- moles of NaOH to the buffer. a) Write down your student name and number b) Write down how the student calculated the final moles of A- and HA after adding the NaOH: moles A Fing =2.0x10 mole - 1.0x10-3mole moles HA Eno= 3.0x10 2mole +1.0x10 3mole c) There is an error in their formula. Identify the error d) Calculate the correct final moles of A and HA

A student prepared 100.0 mL of a buffer in the lab that contains 0.300 M of a weak acid, HA, and 0.200 M of its conjugate base, NaA. The student then added 1.0x10- moles of NaOH to the buffer. a) Write down your student name and number b) Write down how the student calculated the final moles of A- and HA after adding the NaOH: moles A Fing =2.0x10 mole - 1.0x10-3mole moles HA Eno= 3.0x10 2mole +1.0x10 3mole c) There is an error in their formula. Identify the error d) Calculate the correct final moles of A and HA

Chemistry: The Molecular Science

5th Edition

ISBN:9781285199047

Author:John W. Moore, Conrad L. Stanitski

Publisher:John W. Moore, Conrad L. Stanitski

Chapter15: Additional Aqueous Equilibria

Section: Chapter Questions

Problem 110QRT: Consider the nanoscale-level representations for Question 110 of the titration of the aqueous weak...

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Consider the nanoscale-level representations for Question 111 of the titration of the aqueous strong acid HA with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: (a) After a very small volume of titrant has been added to the initial HA solution? (b) Halfway to the equivalence point? (c) When enough titrant has been added to take the solution just past the equivalence point? (d) At the equivalence point? Nanoscale representations for Question 111.
Consider the nanoscale-level representations for Question 110 of the titration of the aqueous weak acid HX with aqueous NaOH, the titrant. Water molecules and Na+ ions are omitted for clarity. Which diagram corresponds to the situation: After a very small volume of titrant has been added to the initial HX solution? When enough titrant has been added to take the solution just past the equivalence point? Halfway to the equivalence point? At the equivalence point? Nanoscale representations for Question 110.
In a laboratory experiment, a student has 1 L of solution containing a weak base at a concentration of 0.300 M. In order to create a buffer, a strong acid is added, which converts some of the base in the solution to its conjugate weak acid to create a buffer. If the student wants to create the most effective buffer that can be equally resistant to both acids and bases how many moles of strong acid should the student add to the buffer? (Please provide your answer to 3 decimal places.)
A chemistry graduate student is given 500. mL of a 0.40 M ammonia (NH3) solution. Ammonia is a weak base with Kb=1.8x 10^-5 . What mass of NH4C1 should the student dissolve in the NH3 solution to turn it into a buffer with pH = 8.85? You may assume that the volume of the solution doesn't change when the NH, C1 is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits.
Please answer both of those questions, because one question leads to another. To prepare an acetic acid/acetate buffer, a technician mixes 31.8 mL of 0.0870 ? acetic acid and 19.7 mL of 0.123 ? sodium acetate in a 100 mL volumetric flask and then fills with water to the 100 mL mark. How many moles of acetic acid are present in this buffer? acetic acid: ________ mol How many moles of sodium acetate are in the buffer? sodium acetate: _______ mol
You are titrating 21.00ml of a 0.850 M solution of NH3(ammonia) with a strong acid. If you add 1.20ml of a solution of a 1.80M solution of hydrochloric acid, what is the final pH of the resulting solution? The Kb for ammonia 1.77x10^-5
The second buffer you will make in lab, Buffer B, will be made by combining the appropriate amounts of 1.8 M acetic acid and 1.0 M sodium hydroxide in a 100.00 mL volumetric flask. The buffer concentration will be 0.5 M. This concentration is the sum of the acetic acid, HA, and the acetate, A–. Calculate the volume in milliliters (mL) of 1.8 M acetic acid needed to make 100.00 mL of 0.5 M solution.
A buffer is prepared such that [CH3COOH]0 = [CH3COO−]0 = 0.050 M. Calculate the volume of 0.10 M NaOH that can be added to 100.0 mL of the solution before its buffering capcaity is lost. Assume the buffer capacity is lost when the ratio [base]0/[acid]0 is less than 0.1 or greater than 10. Give your answer in mL.
1. How do you prepare a 100mL of 0.1 M phosphate buffer?To make 100 mL of 0.1 M phosphate buffer: Calculate the amount of sodium phosphate needed. moles of sodium phosphate = (0.1 mol/L) x (0.1 L) = 0.01 moles mass of sodium phosphate = moles x molar mass = 0.01 moles x 142 g/mol = 1.42 g Dissolve 1.42 g of sodium phosphate in distilled water in a 100 mL volumetric flask. Adjust the pH of the solution to the desired value (usually around 7.4) using a strong acid or strong base. Bring the solution to the final volume (100 mL) with distilled water. 2. From the anterior buffer, how do you make 100mL of 0.05 M? To make 100 mL of 0.05 M phosphate buffer from the 0.1 M stock solution: Calculate the amount of the 0.1 M phosphate buffer needed. moles of phosphate buffer = (0.05 mol/L) x (0.1 L) = 0.005 moles Calculate the volume of the 0.1 M phosphate buffer needed. moles = concentration x volume (in liters) volume = moles / concentration = 0.005 moles / 0.1 mol/L = 0.05 L or 50 mL Measure…
88c. [Tutorial: Titration stoichiometry] This question will walk you through the steps of calculating the volume of titrant required to reach the endpoint based on the volume and concentration of analyte. Consider the standardization of NaOH by titration with C₆H₈O₇ according to the following chemical reaction: 3 NaOH(aq) + C₆H₈O₇(aq) ⇌ Na₃C₆H₅O₇(aq) + 3 H₂O(l) Step 3: Calculate the volume of titrant required to reach the endpoint. Calculate the volume in mL of a 0.200 M NaOH solution needed to neutralize 345 mL of 0.0333 M C₆H₈O₇ standard solution. 88d. Based on the fact that NaOH is a strong base and C6H807 is a weak acid, how would you describe the pH of the solution at the endpoint, where moles of base = 3 times the moles of acid?
In a titration experiment, 0.27 M NaOH is added to 21.8 mL of a 0.35 M H3PO4 solution and reacts according to the equation: 3 NaOH (aq) + H3PO4 (aq)--------------> Na3PO4 (aq) + 3 H2O (aq) How many milliliters of sodium hydroxide solution have been added at the equivalence point (end point)?
The recipe of carbonate buffer is as follows: 15mM sodium carbonate Na2CO3 35mM sodium bicarbonate NaHCO3 3.1mM sodium azide NaN3 (poisonous) You want to make 500mL of this buffer for your upcoming experiments. However, you don’t have enough stock solution of each to make this buffer. Instead of preparing more of each stock you decide to just weight out and mix crystals/powder of each with water. Show your calculations on how much crystals (in grams) of each you should weight out. [Atomic Mass: Na – 23; C – 12; N – 14; O – 16]