A student wishes to make a buffer that has a pH of 4.65.  The student has HNO2 and NaNO2.  Nitrous Acid (HNO2) has a pKa of 3.40 The student makes 100.0 mL of a 0.100 M solution of HNO2.  What mass (in grams) of NaNO2  should the student add to the solution to make a buffer that buffers at a pH of 4.25. (Hint: use the Henderson-Hasselbalch equation to find the molarity, then find the number of moles required to achieve that concentration in 100.0 mL of solution.)

A 35 mL sample of 0.20 M KOH is titrated with 0.25 M strong acid (HX).  What is the pH of the solution after 23.0 mL of HX (strong acid) have been added to the base?     Group of answer choices 1.26 13.03 12.74 12.33 1.67

An aqueous solution contains 0.302 M ammonia (NH3). How many mL of 0.393 M perchloric acid would have to be added to 225 mL of this solution in order to prepare a buffer with a pH of 9.240? mL

A buffer is made by adding 19.4 grams of lithium fluoride to 200.0 mL of 2.00M HF. a) What is the pH of this system before any strong acid or base is added? b) What is the pH after the addition of 200.0 mL of 0.500M HCl? c)What is the pH after the addition of 400.0 mL of 0.500M HCl?

A 1.0 liter solution contains 0.745 M hydrogen fluoride (HF) and 0.786  M sodium fluoride (NaF).  What is the pH of this solution? (Ka for HF is 7.2 x 10 –4) How many moles of solid sodium acetate would have to be added to 2.0 L of 0.293  M acetic acid solution to achieve a buffer of pH 4.77? Assume there is no volume change.      Ka for HC2H3O2 is 1.8  × 10 –5 What molar ratio of sodium acetate to acetic acid,  is required to create a buffer solution having a pH of 4.58 at 25°C?     Ka for HC2H3O2 is 1.8  × 10 –5.

A 1.48 L buffer solution consists of 0.332 M propanoic acid and 0.178 M sodium propanoate. Calculate the pH of the solution following the addition of 0.062 mol HCl. Assume that any contribution of the HCl to the volume of the solution is negligible. The ?a of propanoic acid is 1.34×10−5. PH =  A buffer with a pH of 4.22 contains 0.27 M of sodium benzoate and 0.26 M of benzoic acid. What is the concentration of [H3O+] in the solution after the addition of 0.056 mol HCl to a final volume of 1.6 L? Assume that any contribution of HCl to the volume is negligible. H3O+ =  (these are on the same slide on the homework)

If you have a solution with 1 mole of acetic acid HC2H3O2, which of the following can be added to make a buffer?  Choose all correct answers.     1 mol HCl     0.6 mol HCl     1 mol  NaC2H3O2     0.5 mol  KC2H3O2     1 mol NaOH     0.4 mol NaOH

You take a 1.50 moles of strong acid HCl and a 1.00 moles strong base NaCl and combine them with a total volume of 1.00 Liter. What is the pH of the solution? What is the [OH-] of the solution? What is the [Cl-] in the solution? What is the [Na+] in the solution?

What is the pH of a buffer prepared by mixing 5.0 g of ammonia (NH3) and 20.0 g of ammonium chloride (NH4Cl) in enough water to form 2.50L of solution. The K, of ammonia is 1.76 x 10-5. How many moles of sodium hypobromite, NaBrO, should be added to 1.00 L of 0.050 M hypobromous acid, HBrO, to form a buffer solution of pH 8.80? Assume no volume change when the NaBr is added. K. of HBrO is 2.50 x 10.⁹ How many grams of sodium lactate, NaC3H5O3, should be added to 1.00L of 0.150M lactic acid, HC3H₂O3, to form a buffer solution with a pH of 3.90? Assume no volume change when the sodium lactate is added. K. of lactic acid is 1.40 x 10-4.

What is the pH of a buffer solution that is 0.602 M in hydrofluoric acid and is 0.455 M is potassium fluoride? The K₂ of hydrofluoric acid is 6.4 x 10-4. (Two decimal places)