1- If the bicarbonate ion (HCO3-) concentration in a sample of blood is 0.270 M, determine the carbonic acid (H2CO3) concentration required to buffer the pH of blood at pH = 7.45.
H2CO3(aq) ⇌ HCO3-(aq) + H+(aq) Ka = 5.3 × 10-7
Show all calculations including equation(s) used. Provide your final answer to 3 decimal places.
2- 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 want to make a phosphate buffer in the lab that resembles the bloods phosphate buffer. You start by mixing 1.0 M NaH2PO4 and 2.0 M Na2HPO4.
H2PO4- + H2O ⇌ HPO42- + H+ pKa= 7.21
a. From the mixture and reaction above indicate who the acid and who the base is.
b. Calculate the pH of the phosphate buffer solution?
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 normal ranges, she is suffering alkalosis or acidosis?
3- Like all metal carbonates, calcium carbonate reacts with acidic solutions to produce carbon dioxide gas. It is this reaction that is responsible for limestone fizzing when dilute hydrochloric acid is placed on its surface.
Limestone, which consists mostly of calcium carbonate, has been used in agriculture for centuries. It is spread on fields to neutralise acidic compounds in the soil and to supply calcium, which is an essential plant nutrient.
80 g of CaCO3 is treated with 0.5 litre of a 1M solution of HCl. What volume of CO2 gas, measured at
25˚C and 800 mm Hg can be obtained?
CaCO3(s) + 2HCl(aq) ® CO2(g) + CaCl2(aq) + H2O(l)
Show all equation and all calculations involved to get full marks. Hint: this is a limiting type
Use the following questions as guide and include them in your answer.
i. the limiting reactant is?
ii. the maximum number of moles of CO2 gas that can be produced is?
iii. the volume of CO2 gas that can be produced from this reaction is?