Urine my lord ;-) Composed not only of uric acid but also urea and various ammonia type compounds, plus whatever food/drink breakdown products the body rejects
http://www.ivy-rose.co.uk/HumanBody/Urinary/Urinary_System_Composition_Urine.php "The pH of normal urine is generally in the range 4.6 - 8" Other major component Creatinine