In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Of the 19 patients without sodium bicarbonate added to the medication 11 ( 58 % ) complained of penile pain due to the medication , while only 1 of the 19 men ( 5 % ) who received sodium bicarbonate complained of penile pain .
### Output Text:
Of the 19 patients without <span class="chemical">sodium bicarbonate</span> added to the medication 11 ( 58 % ) complained of penile pain due to the medication , while only 1 of the 19 men ( 5 % ) who received <span class="chemical">sodium bicarbonate</span> complained of penile pain . 