Question 1. NaH2PO4
Explanation: pH is close to pKa2
Question 2. Na2HPO4
Explanation: pH is close to pKa2
Note: pKa2 = -Log(Ka2) = -Log(6.2*10-8) = 7.2
You are instructed to create 400. mL of a 0.39 M phosphate buffer with a pH...
You are instructed to create 400. mL of a 0.39 M phosphate buffer with a pH of 6.2. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. (Enter all numerical answers to three significant figures.) H3PO4(s) + H20(1) =H30+ (aq) + H2PO4 (aq) Kai = 6.9x10-3 H2PO4 (aq) + H20() = H30+(aq) + HPO42- (aq) Ka2 = 6.2x 10-8 HPO42-(aq) + H20(I) = H30+(aq) + PO43-(aq) Ka3 = 4.8 x 10-13 Which of the available chemicals...
You are instructed to create 400. mL of a 0.39 M phosphate buffer with a pH of 6.2. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. (Enter all numerical answers to three significant figures.) H3PO4(s) + H2O(l) = H30+ (aq) + H2P04 (aq) Kai = 6.9 x 10-3 H2PO4 (aq) + H20(1) =H30+ (aq) + HPO42-(aq) Ka2 = 6.2 x 10-8 HPO42-(aq) + H20(I) = H30+(aq) + PO43-(aq) Ka3 = 4.8 x 10-13 Which of...
You are instructed to create 400. mL of a 0.40 M phosphate buffer with a pH of 6.4. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. (Enter all numerical answers to three significant figures.) H3PO4(s) + H2O(l) H3O+(aq) + H2PO4−(aq) Ka1 = 6.9 ✕ 10−3 H2PO4−(aq) + H2O(l) H3O+(aq) + HPO42−(aq) Ka2 = 6.2 ✕ 10−8 HPO42−(aq) + H2O(l) H3O+(aq) + PO43−(aq) Ka3 = 4.8 ✕ 10−13 Which of the available chemicals will you use...
You are instructed to create 200. mL of a 0.63 M phosphate buffer with a pH of 6.0. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. (Enter all numerical answers to three significant figures.) H3PO4(s) + H2O(l) equilibrium reaction arrow H3O+(aq) + H2PO4−(aq) Ka1 = 6.9 ✕ 10−3 H2PO4−(aq) + H2O(l) equilibrium reaction arrow H3O+(aq) + HPO42−(aq) Ka2 = 6.2 ✕ 10−8 HPO42−(aq) + H2O(l) equilibrium reaction arrow H3O+(aq) + PO43−(aq) Ka3 = 4.8 ✕ ...
You are instrucbed to create 900. mL of a 0.59 M phosphate buffer with a pH of 6.4. You have phosphoric acid and the sodium salts NaH2PO4, Na2HPO4, and Na3PO4 available. numerical answers to three significant H3PO4(s)H20)H3 aH2PO4(aq) H2PO4-(aq) + H2O(りーH3O + (aq) + HP042-(aq) Ka2-6.2×10-8 HPO()H20()H3)PO43 (aq) Ka 4.8x10-13 Ka 6.9x10-2 Which of the available chemicals will you use for the acid component of your buffer? O H3PO4 O Na2HPO Na3PO4 Which of the available chemicals will you use...
You are instructed to create 100 mL of a 0.05 M Acetate buffer with a pH of 4.2. You have Glacial Acetic acid (17.4M) and the sodium Acetate NaC2H302, available (Ka=1.8e-5). (Enter all numerical answers to three significant figures.) Copy the results into your lab notebook for use in class. HC2H302(s) + H20(I) = H30+(aq) + C2H302 (aq) What is the molarity needed for the acid component of the buffer? What is the molarity needed for the base component of...
You are instructed to create 180. mL of a 0.06 M Acetate buffer with a pH of 4.0. You have Acetic acid and the sodium salt NaC2H3O2, available. (Enter all numerical answers to three significant figures.) HC2H3O2(s) + H2O(l) equilibrium reaction H3O+(aq) + C2H3O2−(aq) Ka1 = 1.7 ✕ 10−5 What is the molarity needed for the base component of the buffer? How many moles of base are needed for the buffer? How many grams of base are needed for the...
Buffer Practice 1.) You wish to prepare 750 mL of a buffer solution of pH = 7.00 and you decide to use NaH2PO4 as the acid, K2 = 6.2 x 10. You have on hand a 0.175 M solution of this acid. Kai = 7.5 x 103, Ka2 = 6.2 x 10-8, K3 = 4.2 x 10-13 a.) Calculate the pH of the NaH2PO4 solution. b.) Calculate the grams of Na2HPO4 that need to be added to 750 mL of...
Phosphoric acid is a triproccd (K 6.9x10-3, 6.2x10-8, and Ka3 4.8x 10-13). To find the pH of a buffer composed of H2PO4 (aq) and HPO (aq), which pKa value would you use in the Henderson-Hasselbalch equation? O pK 1 = 2.16 O p 2=7.21 O pKa3 12.32 Calculate the pH of a buffer solution obtained by dissolving 11.0 g of KH2PO4(s) and 26.0 g of Na2HPO4(s) in water and then diluting to 1.00 L Number pH= | Phosphoric acid is...
To make 1.00 L of a 0.100 M H2PO4- / HPO42- buffer at pH 6.90 and you start with the NaH2PO4, A. Calculate the mass of NaH2PO4 needed to make the buffer. B. Should HCl or NaOH be added to make the final buffer? Calculate the number of moles of HCl or NaOH that needs to be added. Note: formula mass of NaH2PO4 is 120.