how to measure mg without a scale

[ctreefer]

Hi guys,

I had a case of nudis on my montis about 6 months ago and went the route of getting a coris wrasse. I haven't seen a monti since, but I don't want to risk trading with anyone since I'm concerned they may still be there but are being eaten while the coris is in town. I just recently bought some potassium permanganate, but I have no way of measuring weights down to mg (or grams for that matter). Does anyone know approximately what 50 mg of Potassium permanganate is equal to in teaspoons? I'm guessing its pretty small. Would one of the small scoops from the Ca Salifert test kits be close to the right amount? I can increase the volume to maybe 4L which would mean I need 200mg, but I'm still clueless to the amount.

thanks for any help.

 

[Billybeau1]

Permanganate is very dangerous to use IMO.

What are you hoping to achieve by its use ?

 

[bertoni]

Well, a teaspoon contains about 5ml of water, which is about 5mg. Personally, I'd ask a pharmacist at a drug store to mix up a solution for me.

 

[michaeldaly]

<a href=showthread.php?s=&postid=13986706#post13986706 target=_blank>Originally posted</a> by bertoni
Well, a teaspoon contains about 5ml of water, which is about 5mg. Personally, I'd ask a pharmacist at a drug store to mix up a solution for me.

5ml of water does not weight 5mg it weighs 5g or 5000mg.

 

[ctreefer]

<a href=showthread.php?s=&postid=13986657#post13986657 target=_blank>Originally posted</a> by Billybeau1
Permanganate is very dangerous to use IMO.

What are you hoping to achieve by its use ?

Agreed, its dangerous to use. Similar if I'm not mistaken to chlorine. The solution would be fairly weak but I'll still be certain to use latex gloves and eyewear protection as is recommended. I'm treating for montipora nudibranchs using Eric Borneman's same method.

Not sure how close the mass properties of this is to water. If they were similar I could take a quarter teaspoon divide it in half to get an 1/8th which in water weight would be about 600 mgs and then add that to the water. The solution is supposed to be 50mg/l, so 600mg would require 12liters supposing all this is similar. I'm not certain how close to the 50mg/l the solution needs to be as he only did a test at that level if I'm not mistaken.

good idea/bad idea?

 

[xJake]

The saturation point for KMnO4 in H2O is 6.38 g/100 ml at 20 °C. So 1 tsp. of H2O saturated with KMnO4 at 20 °C would contain about 0.3144 grams of KMnO4. The density of solid KMnO4 at 20 °C is 2.703 g/cm³(mL). So, 1 tsp. of solid KMnO4 at 20 °C would be about 13.32 grams. 20 °C is 68 °F, or room temperature (relatively easy to achieve by setting your thermostat). These are really just estimates, and you should really try to find an accurate metric scale to use; especially for such a potentially dangerous chemical. If you truly cannot find a scale to use, then these estimates should suffice. It's important that you create an environment with a temperature that is as close as possible to 68F, otherwise these estimates will not be accurate. Also, if you can, I would suggest grinding up the crystals into a fine powder via a mortar and pestle (or similar device) as this would make your measurements more accurate. If you do decide to do any grinding then make sure you use a breathing mask to avoid breathing any dust.

 

[michaeldaly]

<a href=showthread.php?s=&postid=13988082#post13988082 target=_blank>Originally posted</a> by ctreefer
Agreed, its dangerous to use. Similar if I'm not mistaken to chlorine. The solution would be fairly weak but I'll still be certain to use latex gloves and eyewear protection as is recommended. I'm treating for montipora nudibranchs using Eric Borneman's same method.

Not sure how close the mass properties of this is to water. If they were similar I could take a quarter teaspoon divide it in half to get an 1/8th which in water weight would be about 600 mgs and then add that to the water. The solution is supposed to be 50mg/l, so 600mg would require 12liters supposing all this is similar. I'm not certain how close to the 50mg/l the solution needs to be as he only did a test at that level if I'm not mistaken.

good idea/bad idea?

Potassium permanagate crystals are lighter than water so I'm not sure about the mass. You could try borrowing a scientific scale if you know any chemists.

I would not bother with the gloves and eye wear, I have worked with it on occasion and got it on my hands witout any negative side effects other than a brown stain.

 

[sweetdreamfiji]

You could try asking the chemistry teacher at your local high school if you could use their scale. It would only take a minute to weigh out 200 mg on a scale. If you are concerned about fumes you could put the scale in the hood.

 

[xJake]

<a href=showthread.php?s=&postid=13990148#post13990148 target=_blank>Originally posted</a> by sweetdreamfiji
You could try asking the chemistry teacher at your local high school if you could use their scale. It would only take a minute to weigh out 200 mg on a scale. If you are concerned about fumes you could put the scale in the hood.

There's an idea. It might be a bit awkward, but I doubt the chemistry staff members would mind. Not to mention that you'd have the peace-of-mind in being able to accurately dose the KMnO4.