Answer to Question #100673 in General Chemistry for Gali

Question

5. Jacinda is attempting to manufacture some aspirin to get rid of her headache. In it, she needs to adjust the pH, so she makes a weak base to use in the process, so she reacts 125 mL of 5 M acetic acid with enough 2.6 M barium hydroxide to react to completion. How many mL of barium hydroxide are used? What is the final concentration of the salt that is produced from this reaction?

Answer 1

Solution.

To find the number of ml of barium hydroxide through the law of equivalents, it is necessary to translate all molar concentrations to normal.

$Cm(CH3COOH) = Cn(CH3COOH)$

$Cn(Ba(OH)2) = 2 \times 2.6 = 5.2 \ N$

Because of this reaction:

$2CH3COOH + Ba(OH)2 = Ba(CH3COO)2 + 2H2O$

Law of equivalents:

$C1 \times V1 = C2 \times V2$

$V(Ba(OH)2) = \frac{Cn(CH3COOH) \times V(CH3COOH)}{Cn(Ba(OH)2)}$

V(Ba(OH)2) = 120.2 ml

Since the law of equivalent quantities of the starting materials are equal, then the amount of substance of salt equal to the amount of substance of a base or acid.

$n(Ba(CH3COO)2) = 5.2 \times 0.1202 = 0.63 \ mol$

The volume of the solution is equal to the sum of the volumes merged into the chemical reactor.

$V = V(CH3COOH) + V(Ba(OH)2)$

V = 245.2 ml

$C(Ba(CH3COO)2) = \frac{n(Ba(CH3COO)2)}{V}$

Cn(Ba(CH3COO)2) = 2.57 N

Answer:

V(Ba(OH)2) = 120.2 ml

Cn(Ba(CH3COO)2) = 2.57 N