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I have posted this on the FB page, but thought I would repost here, just in case there was people who would see it here, but not there. Please forgive me if you get it twice!

Another question for the Brains Trust... My Chem Teacher wants to do a prac for "Reversible Reactions" for our Yr 11 going into Yr 12 class. Apparently the syllabus suggests using Cobalt Chloride (a "Teacher Only" chemical. and the text book has one using Conc HCl (another Teacher only chemical). She wants a prac that the kids can do themselves, rather than a Teacher den. What are other people doing for this?

Cheers
Ian

I am about to prepare the Blue Bottle as a demo

According to Risk Assess, the Cobalt chloride, at 1M, is ok for Seniors, it's an orange dot.
CSIS says it's okay for 7-12, so a green dot.
Am I reading that wrong?

Just checking with the teacher..... they want to use pry powder. 1 Heat it to drive off the moisture and note the colour change, then 2. add Conc HCL to absorb the moisture and ethanol to NOT drive off the water, and note the colour change. So, it is the solid she wanted to use. I think it will just have to be a dem

I've got teacher wanting to do also using solid Cobalt chloride for Reversible and irreversible reactions, we use RiskAssess it clearly states teacher only.

What did everyone else end up doing?

Our Chem teacher did a demo using conc. HCl in a fume cabinet and a solution of 0.1M cobalt chloride. She also heated it and put it in an ice bath. She said it worked well.

Just looking at the cobalt chloride equilibrium system prac. 11-12 can use 0.5M Cobalt Chloride, and if you have a look on riskassess 11-12 hydrochloric acid 8-10 M (25-32% wt/wt) teacher only hydrochloric acid, 10-12 M (32-37% wt/wt), concentrated.

If you do a label for 10M HCL using riskassess it comes up 11-12 which is 32% concentrated in my cupboard. doesn't make sense.

So according to that the kids can do it.

Why do they have to make it so difficult.

I really wish they would work it all out.

Macca - contact Riskassess and let them know that one of them is incorrect. I'm sure they will have it fixed in no time.

My school generally generally follows the Riskassess chemical user groups but they are just recommendations. I guess it's up to school/department policies, head of faculties etc to decide how closely they are followed and the procedure in place if a teacher wants to work outside the recommendations. Below is a screenshot from Riskassess...
I'm not sure i'd allow students to use teacher only chemicals though.

Just a thought.

Definitely agree - user codes are a guideline. If a risk assessment is done and the teacher believes the control measures are adequate, then they could go ahead with pracs outside the user recommendations. They need to take into account the facilities, age of students, number of students, previous behaviour, etc
Caution though, the risk assessment and control measures would need to be spot on as it is this the school will be relying on if there is an incident and Safework get involved. Hopefully though, if the RA is good, then no incident will occur - that is really the primary goal of the RA.

My HT just completed this prac with his year 11/12 class. Although the prac he used didn't ask for conc. HCl at all, just water. After assessing the risks of using the chemical with this particular class, he implemented safety controls to reduce the risk to low and went ahead with the prac as written in the text book.

Yep Melsid, it's the following prac. cobalt chloride equilibrium system prac. that uses the HCl. the reversible Reactions is the one with Colbalt chloride solid teacher only according to risk assess, I apologise that was my original question. One problem is what the teacher believes!!!! lol. then tells me after I question everything that has been booked, oh I haven't read the practical.