How do you convert 290mg sodium to mEq?

To convert from mg to mEq, divide the amount of mg by the atomic weight of the element and multiply by the valence of the element. For sodium, the atomic weight is 23 and the valence is 1. Therefore, to convert 290mg of sodium to mEq: (290 mg / 23) x 1 = 12.6 mEq.