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    Converting % solution to molarity

    Your colleague has started off with 58.44g in 1000ml, which is a 1 mol dm-3 solution, so what he or she has ended up with is a 0.03 mol dm-3 solution. Nothing in that calculation takes into account that your original solution was 3g in 100ml, which is why it is irrelevant and your calculation to...
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    Neutralisation.

    In theory yes, if you were sure that the acid was exactly 0.1M so that it was definitely the hydroxide that was wrong (if 17.5ml 0.1M neutralises it then it would suggest the NaOH is 0.0875M) then you could add more 1M to the solution to bring it up to the right concentration. The problem is...
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    Neutralisation.

    I'm not completely sure what you are asking, but there appear to be two things here: 1) If you want to make 100ml of 0.1M Sodium Hydroxide from 1.0M then it is a dilution of 1/10th, so 10ml of NaOH and make up to 100ml with distilled water 2) However, HCl and NaOH react on a 1:1 ratio, so if it...
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    OCR exam board PAG 7.2

    When setting this up I had two main issues. Firstly the shear amount of plates and equipment needed, as they ask for 10 plates per pair, so potentially 100 per class (at the time we have five biology classes), plus large numbers of bijou bottles. In the end I agreed with the teachers that two...
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    School departing the LA "umbrella" for H&S.......

    Given that the decision is financial, I would try to find out the current cost being paid and make sure that the school is aware of the costs of replacing the key services. CLEAPSS membership through the local authority is about 50% cheaper than going directly (see GL001) - 15p per pupil via...
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    To quarantine or not to quarantine

    If the two classes are looking at the same practical I assume they are in the same year group. If you are using year groups as bubbles, and it is the same teacher, then there should be no need for quarantining or cleaning.
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    Mammal Trap

    No you don't need a licence to use Longworth traps to capture small mammals, however there are specific regulations around shrews because they need to eat very regularly or they die. So if your trap has a smaller release window to allow shrews to escape then you don't need to do anything more...
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    Risk assessments and COSHH

    I think the person carrying out the inspection is being over zealous there. We certainly don't have customised individual risk assessments for the storage of each chemical - the storage and safety information on the Hazcards, combined with one overall storage based risk assessment should be...
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    Max amount of flammables (e.g. ethanol) in prep room's cabinet

    In addition to the overall maximum amount of flammable liquids that can be stored mentioned above, it also comes under the general thinking that CLEAPSS recommend that you shouldn't keep more chemicals than you are likely to use within a reasonable period (e.g. a year). So if you usually use...
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    Cyclohexene and bromine

    It depends on the amount of alkene that you use - the CLEAPSS guide TL010 suggests only using one drop of Cyclohexene, and in that case you can add the waste to a bowl of water and leave in a working fume cupboard to evaporate. For larger amounts then yes you would have to save the waste for...
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    Where would I find a Chem list for A-Level course?

    Having had to resource a college teaching A-level chemistry from scratch a few additional pointers to those listed above: 1) You are best off downloading the documents from Interchange as mentioned by others - many of them have had slight edits from the first versions so don't be tempted to use...
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    Agar failed to freeze

    Agar is solid at room temperature, so it doesn't need to go in the fridge, it will start to set as it cools and gets below about 50oC. You probably want to give it several hours though for it to set properly, depending on how thick a layer you have poured. This thread has mostly been about...
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    Potassium Dichromate Disposal

    Potassium dichromate is much less soluble than Potassium chromate, so if you have swapped them then there will be quite a bit left over that wouldn't have dissolved. As CovTech said above if you work in an establishment that subscribes to CLEAPSS then the Hazcards have a section for disposal...
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    Concentration maths

    Your maths is OK, but works on the basis that you would need 38.66 of 100% Hydrochloric Acid. In reality the concentrated Hydrochloric Acid you will be using is only between 35-38% w/w, which is why you need about 3 times the amount you have calculated.
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    Advice Needed Please...

    My immediate thoughts: 1) If the smell is strong enough that it gives you a headache after being in there for a short period of time then you shouldn't re-enter (and close it off so that others don't go in) and report it to whoever is in charge of H&S for your school / academy as an urgent...
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    Marble Run Track

    If you want something flexible then plastic curtain tracking works well and is cheap (available from Argos, DIY places etc), although the sides aren't raised particularly high so it might not be suitable if you wanted a high release point.
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    Risk assessments

    Just having access to CLEAPSS resources isn't enough, because they are effectively providing you with model risk assessments. For example, they can't take into account that one lab might be an odd shape or have poor ventilation, or that a particular class are badly behaved, or that in the same...
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    Practical Requests

    If the correct equipment isn't being asked for then the best thing to do is to make sure that there is a centralized scheme of work with teacher versions and technician versions of sheets. That way a teacher just needs to ask you for a particular practical number, for example 8.3.2 might be year...
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    Term time only or 52 weeks?

    Yes this is the only other alternative possibility, if you actually have to work 46.5 weeks (rather than that being the amount of time you are being paid for) then factoring in the other 5.5 weeks of the year would be paid holiday, so you would be full time. Worth checking your contract (or...
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    Term time only or 52 weeks?

    It would be odd to be employed for the odd half a week - could 46.5 weeks be the amount of time you are paid for (including holiday), not the amount of time you have to be in work? For example, 39 weeks of term time + 1 week of inset days + 1 week in the holidays = 41 weeks, then your holiday...
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