Using some of the following reagents, describe the preparation of 500 mL, pH 7 citric acid

1. 8 M citric acid

1. 2 M sodium dihydrogen citrate

1. 5 M sodium hydrogen citrate

0. 8 M sodium citrate

0. 1 M HCl

0. 1 M NaOH

Citric acid: Ka1=7. 4 x 10-4, Ka2=1. 7 x 10-5, Ka3=4. 0 x 10-7