Chem 26.1 THVQR (Midterms) 1. The results for the determination of acetaminophen (in milligrams) in ten separate tablets of a pain reliever are

tabulated below.

224.3 229.4 239.4 253.1 246.3 261.7 255.5 240.4 253.5 249.7

Report the mean, median, range, and standard deviation for these data

2. The rate of haemoglobin (Hb)-carbon monoxide reaction,

4Hb + 3CO Hb4(CO)3 has been studied at 20°C. Concentrations are expressed in micromoles per liter (μmol/L).

Concentration (μmol/L) Rate of disappearance of Hb (μmol/L·s) [Hb] [CO]

3.36 1.00 0.941 6.72 1.00 1.88 6.72 3.00 5.64

a) Write the rate equation for the reaction. b) Calculate for the rate constant for the reaction. c) Calculate the rate, at the instant when [Hb] = 1.50 and [CO] = 0.600 μmol/L.

3. A 100.0 mL of 0.200 M buffer having a pH = 4.500 is needed to be prepared from 3.50 M acetic acid and solid ammonium acetate (FW = 77.08248). A) What volume of acetic acid (in mL) and amount of ammonium acetate (in grams) must be combined to prepare the buffer solution? B) What is the resulting pH when 3.00 mL of 0.100 M NaOH was added to a 10.0 mL aliquot of the buffer solution? C) What is the resulting pH when 3.00 mL of 0.100 M HCl was added to a 10.0 mL aliquot of the buffer solution?

4. Consider the following equilibrium reaction:

H+ + HCO3- H2CO3 H2O + CO2 (a) A person suffering from anxiety begins breathing rapidly, and in effect exhales carbon dioxide at a faster

rate than a normal person does. What is its effect on the blood’s pH? (increase, decrease, no effect) (b) Breathing in a paper bag allows a person to breathe in carbon dioxide instead of oxygen. What is its effect

on the blood’s pH? (increase, decrease, no effect)

5. A 0.6234-g sample that might contain NaOH, Na2CO3, NaHCO3 or a permissible mixture of the bases was dissolved in 100.0 mL of boiled distilled water. A 25.00-mL aliquot was withdrawn and titrated with 0.1062 F HCl by the double-indicator method. It was found out that 10.095 mL of the acid were required to reach the phenolphthalein endpoint. Methyl orange was then added to the solution and the titration was continued using an additional 3.2075 mL of the acid. (a) Identify the base or mixture of bases in the sample (b) Calculate the percentage of each in the sample

6. A certain experiment was done to determine the Ksp of Mg(OH)2. A 10.00ml solution of 1.00M Mg(NO3)2 was mixed with 20.00ml of 1.00M NaOH and was filtered. The precipitate was then suspended in 250.0 ml of distilled water. A 50.00ml aliquot of the solution required 9.92 mL of 0.00125 M HCl to reach the endpoint. If the theoretical Ksp of 7.1 x 10 –12, calculate the percent error.