CHEM214 - 1.2 through 3.3

Aspirin has a pKa of 3.4 What is the ratio of A- to HA? the stomach (pH = 1.4)

0.01:1

65mM is how many M?

0.065M

You mix 0.5mol of Acetic Acid and 0.1mol of Sodium Acetate in 1L of H2O. pKa of Acetic Acid is 4.8! What is the pH?

0.5 - 0.1 4.8 + log (0.1/0.5) = 4.1

If you have a total of 0.6 moles of CH3COOH, how many moles of NaOH would you need to completely neutralize CH3COOH?

0.6 moles of NaOH *due to only one of ionization

You start with a solution of 0.6mol of acetic acid and then add 0.1mol of NaOH. What is the pH of the new solution? (pKa = 4.8)

0.6mol 0.1mol -0.1mol 0.1mol 0.5mol 0mol 4.8 + log(0.1/0.5) = 4.1 pH

You start with a solution of 0.8mol of Acetic Acid and then add. 0.2mol of NaOH. 1L solution and pKa = 4.8 What is the pH of the new solution?

0.8 - 0.6 4.8 + log (0.2/0.6) = 4.32

Aspirin has a pKa of 3.4 What is the ratio of A- to HA? the blood (pH = 7.4)

10,000:1

pKa = 3.8 Good buffer range would be?

2.8 to 4.8 *Buffer Range is -1 and +1 of the pKa

Lactic acid buffer solution (pKa = 3.9) contains 0.50M sodium lactate and 25mM lactic acid. What is the pH of this buffer?

25mM / 1000 3.9 + log (0.5/0.025) = 5.2 pH

What are the maximal number of H-bonds that can form to one water molecule?

4

pH of 7mM KOH?

7mM / 1000 = 0.007M pOH = -log [0.007M KOH] = 2.14 pH + pOH = 14 pH + 2.14 = 14 pH = 11.86

Which is the stronger acid? Acidic Acid (pKa = 4.76) Bicarbonate (pKa = 10.25)

Acidic Acid because the lower the pKa, the stronger the acid

Which is strongest of Non-Covalent interactions?

Charge-to-Charge interactions

Describe Amphipathic Molecule and give an example

Examples: Phospholipid Vitamin A An Amphipathic Molecule has a Hydrophilic Polar region and a Hydrophobic Non-Polar region.

Which is driving force of protein folding?

Hydrophobic

What will Vitamin A do in water?

Neither become soluble or insoluble

Where would benzene accumulate?

Oil

Where would Salt accumulate?

Water

Where would Urea accumulate?

Water

pH = 3.5, what is the [H+]?

[H+] = 10^-pH = 10^-3.5

What are the units of M?

mol/L

What is the [OH-] for a pH = 3.6

pH + pOH = 14 3.6 + pOH = 14 [OH-] = 10^-pOH [OH-] = 3.98 x 10^-11

pH of 0.04M HCl?

pH = -log [0.04M HCl] = 1.4

Draw the titration curve for Glycine pKaCOOH = 2.3 pKaNH3 = 9.7

pI = 2.3 + 9.7 / 2 = 6

Calculate the pI of Valine

pI = pKa1 + pKa2 / 2 = 2.3 + 9.72 / 2 = 6

What happens if you add an acid to the below buffered solution of Ethanoic Acid? CH3OOH yields CH3COO- + H+

the buffered solution will react to the new acid removing the H+ and make ethanoic acid