One way to prepare the HEPES buffer involves preparing solutions of the sodium salt form of HEPES (A) and the weak acid form of HEPES (HA) and then combining the solutions to obtain a buffer with the desired pH and concentration. CORRECT; see section 2.4 In preparing 250 mL of 1.0M stock solutions of the A and HA forms of HEPES (supplied as solids by the manufacturer with molar masses of 260.3g.mol-¹ and 238.3g.mol-¹, respectively), what masses of the acid (HA) and the conjugate base (A) would be needed? Round to the nearest whole number. mass of HA (g) = 59.58 mass of A (g) = 65.08 (Tolerance is +/- 2%) eTextbook and Media Hint X INCORRECT; see section 2.4 Calculate the volume of each stock solution needed to prepare 1.0 L of the 0.10 M HEPES buffer at a pH = 8.0. volume HA (mL) = i 100 volume A (mL) = i 100 (Tolerance is +/- 2%)

Three buffers are prepared with equal concentrations of formic acid and sodium formate (Buffer 1), hydrofluoric acid and sodium fluoride (Buffer 2), and acetic acid and sodium acetate (Buffer 3). Rank the three buffers from highest to lowest pH at which they can buffer a solution (i.e., their buffering pH).(a) 1, 2, 3(b) 3, 2, 1(c) 2, 1, 3(d) 3, 1, 2

A chemistry graduate student is given 250. mL of a 1.40M trimethylamine ((CH,) N) solution. Trimethylamine is a weak base with K, =7.4 × 10 *. What 3 mass of (CH,) NHCI should the student dissolve in the (CH, N solution to turn it into a buffer with pH =10.85? 3 You may assume that the volume of the solution doesn't change when the (CH,) NHC1 is dissolved in it. Be sure your answer has a unit symbol, and round it to 2 significant digits. olo x10 Ar ? Explanation Check © 2022 McGraw Hill LLC. AlL Rights Reserved. Terms of Use | Privacy Center | Accessibility

Please calculate the pH of a buffer solution made up of citric acid and potassium citrate. The solution was made by dissolving 0.770 mol of sodium citrate, and 0.770 mol of citric acid in 1.5 liters of water. (Please assume the total volume of the solution is also 1.5 L) (The Ka for this system = 7.41 x 10-4) (Please answer with 3 sig. figs.)

a) A student prepares an 750.0 mL buffer solution with a pH of 4.85 by adding sodium acetate to a solution of acetic acid. However, they forgot to document the mass of NaC2H3O2 added to the beaker. Fortunatelly, they know that the concentration of HC2H3O2 is 0.235M. Determine the mass, in grams, of NaC2H3O2 that must have been added to the solution. (Molar Mass of NaC2H3O2=82.0343 g/mol)  b) 10 mL is accidentally spilled into the buffer solution from part a. Determing the new pH of the solution.

Ammonia is a convenient buffer system in the slightly basic range. (a) What is the pH of a buffer solution containing 46 g of NHĄCI dissolved in 1.00 L of 0.920 M NH3? pH = i (b) How many moles of acid are required to change the pH of this solution by 0.07 pH units? i mol (c) Suppose 4.8 mL of 11.8 M HCI solution is added to 146 mL of the solution of Part (a). Calculate the new pH. pH = i