5) You need to make 250.0 mL of a buffer with a pH of 4.10, in the chemical storage room you found some formic acid, HCHO2, pK, = 3.74 and 35.9 grams of sodium formate, NaCHO2. How many moles of formic acid should you use?

5. A buffer is made by mixing 1.250 mol formic acid, HCOOH, with 0.750 mol sodium formate, HCOONa in enough water for a total volume of 1.00L. The Ka of formic acid is 1.87 x 10-4 a. What is the pH of this buffer? b. If 0.075 mol HCI is added to this buffer, what is the pH of the resulting buffer? (assume no volume changes) c. If 0.055 mol NaOH is added to this buffer, what is the pH of the resulting buffer? (Assume no volume changes)

For humans to maintain the pH of their blood close to 7.4, the body uses three buffer systems: carbonate, phosphate and proteins. If the pH of the blood goes below 6.8 or above 7.8, death may result. Imagine you want to make a phosphate buffer in the lab that resembles the bloods phosphate buffer. You start by mixing 0.95 M NaH2PO4 and 0.68 M Na2HPO4. H2PO4-  + H2O ⇌  HPO42-  + H+  pKa= 7.21  (5 marks total) a. From the reaction above indicate the weak acid and the conjugate base involved in making this buffer. (2 marks) b. Calculate the pH of the phosphate buffer solution. Provide your answer with 2 decimal places (2 marks) c. If the pH calculated in b. was the blood pH of an actual patient, would you say this patient’s blood pH is in the normal range or are they suffering from alkalosis or acidosis? (1 mark)

You have  0.100 M  solutions of acetic acid ( p?a  =  4.76 ) and sodium acetate. If you wanted to prepare  1.00 L  of  0.100 M  acetate buffer of pH  4.00 , how many milliliters of acetic acid and sodium acetate would you add?

What is the pH of a buffer that contains 0.356 M H2C6H606 and 0.647 М НС,Н,О6? Ka1 = 7.9 × 10-5 Ka2 = 1.6 x 10-12 IMPORTANT: When entering your answer: • Erter the number only (no units) • Do not leave any spaces • Use a leading zero before the decimal when necessary Report your number to 2 decimal places (regardless of the significant figures) • Correctly round your answer to the 2nd decimal place (allowed margin of error is only + 0.01, so always use un- rounded numbers in your calculations) Examples: 0.12 or 9.87

6.

A buffer can be prepared from a weak acid, HA, and it's conjugate base, A⁻. A 1L solution is prepared in which the concentrations are [HA] = 0.1M and [A⁻] = 0.2 M. The pKa of HA is 6.4. What is the pH of this solution before and after 50 ml of 1M HCl, a strong acid, is added?

7. A solution was made by mixing 50.0 mL of 0.750 M HCN with 25.0 mL of water. What is the pH of this solution? The pka of HCN = 9.31. 8. One of the compounds featured on the TV series "Breaking Bad" was hydrofluoric acid (HF), pKa = 3.14. a) A solution of HF has a pH = 1.77. What was the initial [HF] for this solution in mol L-1? b) What is the equilibrium concentration of F in this solution in mol L-1? c) What is the percent ionization of HF in this solution?

You have been given 0.200 Molar solutions of hydrocyanic acid and potassium cyanide. The Ka of HCN = 4.9x10-10. If you wanted to make a buffer with a pH = 9.00, would you add a greater volume of the HCN solution or the KCN solution?  More HCN equal amounts of each more KCN

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 finl =2.0x102 mole - 1.0x10-3mole moles HA na = 3.0x102mole +1.0x10-3mole c) There is an error in their formula. Identify the error d) Calculate the correct final moles of A and HA