A choice is to do a different kind of double displacement reaction. For example, copper sulfate with sodium hydroxide is known to form a blue precipitate.. These chemicals have other hazards that need to be considered. You can check their SDS or look them up in the Rehab Lab site.
This link is nice to have and a great reference. In my opinion, please remember that perusing various SDS (from different vendors) for the chemicals is always best!
Regards, Yamy
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Yamaira I. Gonzalez, PhD
Yamy LLC
302-388-9368
gonzalyi**At_Symbol_Here**gmail.com
From: Ralph Stuart <rstuartcih**At_Symbol_Here**ME.COM>
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Sent: Tuesday, January 19, 2016 7:57 AM
Subject: Re: [DCHAS-L] HS teacher request info