When we have to do a buffer solution we always have to choose the reaction that has the pKa closer to the desired pH value. When we find the pKa values we will obtain:

$pKa_1=-Log[6.9x10^-^3]=2.16$

$pKa_2=-Log[6.2x10^-^8]=7.20$

$pKa_3=-Log[4.8x10^-^13]=12.31$

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which $H_2PO_4^-^1$ is the acid and $HPO_4^-^2$ is the base. Therefore the answer for the first question is B and the answer for the second question is C.

8 0

3 years ago

How many liters of 4 M solution can be made using 100 grams of lithium bromide?

Misha Larkins [42]

Add 450 million grams to the solution

7 0

3 years ago

A student determines the molar mass of acetone, CH3COCH3, by the method used in this experiment. She found that the equilibrium

Alexandra [31]

Answer:

(a). 4°C, (b). 2.4M, (c). 11.1 g, (d). 89.01 g, (e). 139.2 g and (f). 58 g/mol.

Explanation:

Without mincing words let's dive straight into the solution to the question.

(a). The freezing point depression can be Determine by subtracting the value of the initial temperature from the final temperature. Therefore;

The freezing point depression = [ 1 - (-3)]° C = 4°C.

(b). The molality can be Determine by using the formula below;

Molality = the number of moles found in the solute/ solvent's weight(kg).

Molality = ( 11.1 / 58) × (1000)/ ( 90.4 - 11.1) = 2.4 M.

(c). The mass of acetone that was in the decanted solution = 11.1 g.

(d). The mass of water that was in the decanted solution = 89.01 g.

(e). 2.4 = x/ 58 × (1000/1000).

x = 2.4 × 58 = 139.2 g.

(f). The molar mass of acetone = (12) + (1 × 3) + 12 + 16 + 12 + (1 x 3) = 58 g/mol.

7 0

3 years ago