<prompt> A patients urine is collected for 2 hours, and the total volume is 600 milliliters during this time. Her urine osmolarity is 150 mOsmL, and her plasma osmolarity is 300 mOsmL. What is her free water clearance?5.0 mlmin2.5 mlmin0.0 mlmin-2.5 mlmin  <response>: Free water clearance is calculated as: urine flow rate 600 ml2 h, or 5 mlmin - osmolar clearance urine osmolarity x urine flow rateplasma osmolarity. Therefore, free water clearance is equal to 2.5 mlmin. 