Physical Chemistry Answers

What is the change in the internal energy of a system that absorbs 2,500 J of heat and that does 7,655 J of work on the surroundings in J? 

Calculate the value of ΔE in joules for a system that loses 50 J of heat and has 150 J of work performed on it by the surroundings.

n 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

]

n 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

]

Hydrofluoric acid has a Ka value of 7.2x10−4. What is the pH of a 0.04M solution of hydrofluoric acid

Meat I'd stored in a refrigerator to last longer

A buffer solution is prepared by dissolving 1.50 g each of benzoic acid, C7H6O2, and

sodium benzoate, NaC7H5O2, in 150.0 mL of solution. [Ka = 6.3 x 10-5] a. What is the pH of this buffer solution? b. Which buffer component must be added, and in what quantity, to change the buffer pH to 4.00? c. What quantity of 2.0 M NaOH or 2.0 M HCl must be added to the original buffer to change the pH to 4.00.

A buffer solution is prepared by dissolving 1.50 g each of benzoic acid, C7H6O2, and

sodium benzoate, NaC7H5O2, in 150.0 mL of solution. [Ka = 6.3 x 10 -5 ]

a. What is the pH of this buffer solution?

b. Which buffer component must be added, and in what quantity, to change the

buffer pH to 4.00?

c. What quantity of 2.0 M NaOH or 2.0 M HCl must be added to the original buffer to

change the pH to 4.00.

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 ]

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]