Answer to Question #152623 in General Chemistry for amethyst grande

Question

1. Using some of the following reagents, describe the preparation of 500 mL, pH 7 citric acid
1.8 M citric acid (H3C6H5O7, MW = 192)
1.2 M sodium dihydrogen citrate (NaH2C6H5O7, MW = 214)
1.5 M sodium hydrogen citrate (Na2HC6H5O7, MW = 236)
0.8 M sodium citrate (Na3C6H5O7, MW = 258)
0.1 M HCl
0.1 M NaOH
distilled water
For citric acid, Ka1 = 7.4 x 10-4, Ka2 = 1.7 x 10-5, Ka3 = 4.0 x 10-7

2. Calculate the pH of a 20-mL 0.45 M of dimethylamine at the following points in the titration (titrant = 0.15 M HCl)
A. Initial pH
B. 5 mL before equivalence point
C. Equivalence point
D. 5 mL after equivalence point
2.1 Sketch the titration curve. Label the axes, equivalence point, and the buffer region.

Answer 1

1.8 M citric acid (H3C6H5O7, MW = 192)

1.2 M sodium dihydrogen citrate (NaH2C6H5O7, MW = 214)

1.5 M sodium hydrogen citrate (Na2HC6H5O7, MW = 236)

0.8 M sodium citrate (Na3C6H5O7, MW = 258)

0.1 M HCl

0.1 M NaOH

distilled water

For citric acid, Ka1 = 7.4 x 10-4, Ka2 = 1.7 x 10-5, Ka3 = 4.0 x 10-7

2. D. 5 mL after equivalence point