Chemistry Answers

Prepare 100 mL of 0.200 bicarbonate buffer, pH 10 by calculating the mass of sodium bicarbonate and sodium carbonate. 

a. Use the Henderson-Hasselbalch equation to calculate the volume of each stock

solution needed.

pH = pKa + log [conjugate base] / [weak acid]1

b. Check your calculations with other students. See the instructor if there is uncertainty.

c. Make the solution and check the pH of a portion of your buffer solution using the pH

meter.

L = 245μL 

solution:

Preparation of Bicarbonate Buffer

Calculated Volume

CH₃COOH ____________________

KH₂PO4 ____________________

Actual pH of the buffer: ____________________

find the vapor pressure of a solution containing 35.0g calcium chloride (CaCl2) in 750.0g water. Note that the P water= 47.1 torr at 37.0C

Compounds A and B was discovered by a group of scientists. Compound A is a dipeptide, optically inactive. While compound B is a tripeptide and optically active. Compound A is formed when compound C and compound D joined together by condensation reaction. Whereas monomers E and F are formed by modifying the compounds C and D. Polymer G is formed by the condensation reaction of monomers E and F.

Draw the possible structural formulae of compounds A, B, C, D, E, F and polymer G.

Label the peptide bond(s) for compounds A and B.

With the aid of diagram, discuss why compounds A and B are classified as an optically inactive compound and optically active compound, respectively?

Draw the possible structural formulae for repeating unit of polymer G.

How would you distinguish between polymer G and their repeating unit?

Dichlorodifluoromethane, CCl2F2, a refrigerant, is prepared from the reaction of CCl4 and HF.

CCl4 + 2HF → CCl2F2 + 2HCl

What will happen when 3.00 grams of CCl4 reacts with 3.00 grams of HF?

Which is the limiting reagent?

How much of the excess reagent remains unreacted?

How many grams of CCl2F2 was produced?

What will happen when 3.00 grams of CCl4 reacts with 3.00 grams of HF?

How many molecular orbitals does CO2 have?

22. 2.76 g of silver carbonate on being heated yields a reduce weigh

a) 2.32 g b) 3.32 g c) 1.36 g d) 0.32 g 

8.8 moles of carbon dioxide is formed in CH4+2O2–>CO2+2H2O. How many grams of methane reacted

If sulfuric acid, acetic acid, and nitric acid reacts with iron, are they a single displacement reaction? If not what kind reaction are they and please be specific.

In a Laboratory, you have the following chemicals available:

1.0 M NaOH, 1.00 M HCl, 1.00 M H3PO4, NaH2PO4 (s), Na2HPO4 (s), and Na3PO4 (s).

Describe TWO ways of making 1000 mL of a buffer of pH = 12 (Use only the above

chemicals, plus distilled water.)

[Given: H3PO4 - Ka1 = 6.9 x 10-3; NaH2PO4 - Ka2 = 6.2 x 10-8 ; Na2HPO4 - Ka3 = 4.8 x 10-13]