Interesting side note:

Toilet bowl cleaner is 9% HCl and will burn your bum. A friend sat on some the custodians left on the seat. She wasn't happy.

Hmm. If they have goggles and wash up spills I don't think it is going to hurt anyone. If you spilled some on a tender area and didn't wash it off on the other hand......

Jarral Ryter
Senior Chemistry Lecturer/Lab and Safety Manager
Western State Colorado University

970.943.2875
western.edu
jryter**At_Symbol_Here**western.edu

-----Original Message-----
From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Stuart, Ralph
Sent: Monday, February 27, 2017 9:11 AM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: [DCHAS-L] HCl concentration and hazard

Over the weekend, several of us attended a workshop to discuss chemical hazard assessment needs with high school teachers. As the example activity to assess the hazards of, we used the "Hollow Penny" activity described at http://zushma.com/images/Hollow_Penny_Activity.pdf

This protocol calls for 6M HCl to be used to digest the zinc interior of the penny. One of the teachers commented that they are uncomfortable with using HCl this concentrated with the teen age students she oversees, so she uses 3 M HCl and lets the penny digest over the weekend so there's enough time to do the job. Other teachers use the 6 M HCl in a lab setting (i.e. students do the hands on work), whereas others said that they did this only as a demo (i.e. the teacher was the only person who touched the acid until the hollow penny is decontaminated). Some teachers avoided this activity altogether. Interestingly, the SDS's we found on the web for HCl indicated that any concentration above 0.1 M has both the corrosive and irritant designations. The 0.1 M SDS I found showed only an irritant designation.

We are not second guessing anyone's professional judgement as to which option they chose. Previous discussion that day made it clear that factors such as 1) the facilities and equipment available, 2) the nature of the students involved in the class and 3) the availability of PPE all made a difference in what people decided to do. These factors vary widely from school to school.

There are three questions we'd like the list's thoughts on:
- Is there a significant hazard difference between 6 M and 3 M HCl in the high school lab setting?
- How would you determine this difference from GHS (or other) information available for these solutions?
- Does the choice of which approach (lab, demo, avoid the activity) impact the educational value of the class?

Thanks for any help with this.

- Ralph

Ralph Stuart, CIH, CCHO
Environmental Safety Manager
Keene State College
603 358-2859

ralph.stuart**At_Symbol_Here**keene.edu

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This e-mail is from DCHAS-L, the e-mail list of the ACS Division of Chemical Health and Safety.
For more information about the list, contact the Divisional secretary at secretary**At_Symbol_Here**dchas.org

---
This e-mail is from DCHAS-L, the e-mail list of the ACS Division of Chemical Health and Safety.
For more information about the list, contact the Divisional secretary at secretary**At_Symbol_Here**dchas.org

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