A 70 kg young adult male is admitted to the hospital and tests reveal he has a plasma Na+ concentration of 108 mEq/liter. Recall normal plasma Na+concentration is 140 mEq/liter. In order to correct for this abnormality how much of a 5% NaCl solution is necessary to be administered intravenously in order to raise the serum Na+ from 108 mEq/liter to 136 mEq/liter?

The MW of NaCl is 58. 

Remember total body water (TBW) is about 60% of body weight and all body fluid compartments are in osmotic equilibrium.

So, (Na)/ECW = (K)/ICW = (Na+K)/TBW

Hint: there is a net change in Na with no change in K.