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: Acute analgesic and antiinflammatory activities were ascertained using acetic acid induced writhing model ( mice ) and carrageenan - induced rat paw edema model , respectively .
### Output Text:
Acute analgesic and antiinflammatory activities were ascertained using <span class="chemical">acetic acid</span> induced writhing model ( mice ) and <span class="chemical">carrageenan</span> - induced rat paw edema model , respectively . 