Strong base is dissolved in 625 mL of 0.400 M weak acid (Ka 4.48 x10) to make a buffer with a pH of 4.08. Assume that the volume remains constant when the base is added Calculate the pKa value of the acid and determine the number of moles of acid initially present. ncorrect. Use the volume and concentration in the question to find moles. Number Number pK,434 2.5 mol HA Molarity is the number of moles per liter When the reaction is complete, what is the concentration ratio of conjugate base to acid? Number НА How many moles of strong base were initially added? Number mol OH

K4 for acetic acid is 1.7 105 at 25C. A buffer solution is made by mixing 52.1 mL of 0.122 M acetic acid with 46.1 mL of 0.182 M sodium acetate. Calculate the pH of this solution at 25C after the addition of 5.82 mL of 0.125 M NaOH.

Repeat the procedure in Exercise 61, but for the titration of 25.0 mL of 0.100 M pyridine with 0.100 M hydrochloric acid (Kb for pyridine is 1.7 109). Do not calculate the points at 24.9 and 25.1 mL.

A 1.0L buffer is made at 25°C that consists of 0.80 mol of a weak acid HA and 0.80 mol of its conjugate base A-. The acid ionizarion constant is Ka= 1×10^-4. To this buffer solution 0.80 mol NaOH is added. Assuming that the volume change due to the added NaOH is negligible, calculate pOH in the resulting solution.

One drop, 0.200 cm3, of 1.00 mol dm-3 of aqueous sodium hydroxide, NaOH, solution is added to 25.0 cm3 of a phosphate buffer that is 0.040 mol dm-3 in KH2PO4(aq) and 0.020 mol dm-3 in K2HPO4(aq). Calculate the resulting pH of the solution given that the second acid dissociation constant, pKa2, for phosphoric acid is 7.21.

Consider a buffer solution that contains 0.55 M NH2CH2CO2H and 0.35 M NH2CH2CO2Na. pKa(NH2CH2CO2H)=9.88. a. Calculate the change in pH if 0.155 g of solid NaOH is added to 250 mL of this solution. b. If the acceptable buffer range of the solution is ±0.10 pH units, calculate how many moles of H3O+ can be neutralized by 250 mL of the initial buffer. c. Calculate its pH.

What will be the appropriate pH of a buffer prepared by mixing 100 ml of 0.1 M Na2HPO4 and 100 ml of 0.1 M NaH2PO4? (For H3PO4, pKa1 = 2.1; pKa2 = 6.8; pKa3 = 12.5) Ans in 2 significant figures

A buffer is prepared using lactic acid (HLac) and sodium lactose (NaLac). 0.300 dm3 of the 0.500 mol.dm3 HLac solution is mixed with 0.300 dm3 of 0.300 mol.dm3 NaLac solution to prepare the buffer. Ka for lactic acid is 1.4 x 10-4 . Calculate the PH of the lactic acid before it is mixed with the NaLac to form a buffer  Calculate the PH of the buffer What will the PH of the buffer solution be after 5.0 cm3 of 0.200mol.dm3 NaOH has been added to only 100 cm3 of this buffer?

When titrating a 25 mL solution of 0.20M CH3COOH with 0.10M KOH, you realize you forgot to add an indicator initially. You've added 10 mL of KOH to the flask of acid. Ka of CH3COOH = 1.8 x 10^-5 1) Calculate the pH at this point 2) What color would your solution be if you add 40 mL KOH more. And a few drops of clorophenol blue indicator at this point. Why?

1). You are running an experiment and need to keep your solution within a certain pH range:  3.5 +/- 1pH unit.  Choose a buffer system (e.g. a conjugate acid/base) with a pKa in the appropriate range.. Assuming you have 0.2M stock solutions of the acid and conjugate base, calculate the L of each need to make 400 mL of buffer. Describe clearly your protocol for making the buffer solution to the desired pH.   Calculate pH for the following.  Add 100 mL of 0.100 M HCl to pure water Add 100 mL of 0.100 M HCl to the 400 mL of buffer you made Add 100 mL of 0.100 M NaOH to pure water Add 100 mL of 0.100 M NaOH to the 400 mL of buffer you made