John Cuthber

On 1/21/2023 at 2:39 PM, Genady said:

For example, most drivers believe that their driving is above average.

It is important to recognise that they might be right.
For the same reason that most people earn  less than the average salary.

 

6 hours ago, dimreepr said:

Would you like to think you're stupid?

I think the question should be "would you like others to think you are stupid?".

36 minutes ago, Genady said:

"The number twice as big as the largest number we thought was possible."

We already thought that number was possible.

I understand that I can write  "two up arrow   up arrow  four is 65536". Which letters didn't you like?
More generally.

The Berry paradox is a self-referential paradox arising from an expression like "The smallest positive integer not definable in under sixty letters" (a phrase with fifty-seven letters).

https://en.wikipedia.org/wiki/Berry_paradox

2 hours ago, geordief said:

Are there numbers that are to large for us to represent?

Probably not because we can get creative about the way we express them.
https://en.wikipedia.org/wiki/Knuth's_up-arrow_notation

On 1/20/2023 at 5:48 AM, jlbarkley said:

  How would I find an exact pH of 7, 7.1, 7.2, 7.3.....  etc. to even be able to figure out the absorbance?

Buffer solutions and/ or a pH meter.
But you will run into a problem.
You can set up a calibration and draw a graph of absorbance vs pH.
But it will depend on the concentration of the dye as well as on the pH.
It is difficult to be sure that you always have the same concentration of dye.
Most dyes are a bit unstable and a lot of them are not supplied as pure materials, but as crude products containing salt etc.
So, you would have to make a fresh calibration for each set of samples.
If you are going to do that- and use a pH meter to do it- you might as well just use the pH meter to determine the pH of your sample.

But there's another pitfall in this analysis.

pH meter probes always carry some buffer into the solution which you are trying to measure.
And that changes the pH of the sample.
To measure the pH of very dilute materials (like drinking water or even river water) you need specialist equipment.
I suggest that you contact the people who make pH meters and ask for their advice.

 

On 1/17/2023 at 6:35 PM, observer1 said:

RESULT:- LITERALLY NO REACTION

What were you expecting?

1 hour ago, vishvajit said:

when calcium carbonate (caco3) and sodium bicarbonate NaHCO3 are added to each other a reaction does occurs which producs sodium carbonate Na2CO3 and calcium hydrogen carbonate (ca(hco3)2). in this reaction the sodium bicarbonate and calcium carbonate acts as an acid or base which reacts to form salt and water also releasing carbon dioxide as a byproduct. the reaction is endothermic or generates heat. 

Why would you post that in a thread where someone has actually done the experiment and told you that there is

" LITERALLY NO REACTION"?

9 hours ago, JacobNewton said:

saw a IQ puzzle book that rated subjects on the basis of their reactions to real world situations, e.g, what would you do in such and such a situation, choose from option a, b or c. Do you think that's an accurate appraisal of IQ?

Not if you apply it to people who are dead.

9 hours ago, JacobNewton said:

Einstein: 160

Da Vinci: 200

9 hours ago, JacobNewton said:

Interestingly the highest recorded IQ of all time is attributed to a mathematics whiz, Marylin Vos Savant, who scores 220 on the IQ scale. 

Equally interestingly
" Guinness retired the "Highest IQ" category in 1990 after concluding IQ tests were too unreliable to designate a single record holder."
From
https://en.wikipedia.org/wiki/Marilyn_vos_Savant
Fundamentally, IQ is a measure of how well you do in IQ tests and it measures nothing else.

4 hours ago, JacobNewton said:

Anybody with IQs in the 180 range, for instance? 

Yes.
So?
Here's an interesting observation.
The IQ test was designed to identify school kids who were struggling with education in order that they could get extra help.
But the people you see on the internet asking about IQ are neither schoolkids, nor do they have cognitive / learning issues.

They just sound like it.


 

12 hours ago, JacobNewton said:

On that note, have you watched Derren Brown? Mind reading stuff? he's done some pretty amazing tricks in his time

Yes.
And he's quite honest about the fact that they are illusions; not real.

12 hours ago, JacobNewton said:

well, i posted that above video by way of said proof

And would you accept this as proof of a flying pig?

or do you understand that video is quite easy to fake?

"Will science ever stagnate and come to a halt?"

Most  Friday afternoons

I'm fairly sure that sodium bicarbonate will float in methylene bromide, but calcite will sink.

13 hours ago, JacobNewton said:

No reason to believe they were fake

Yes there is.
The reason is science.

10 hours ago, JacobNewton said:

.how do u explain THIS

Sure

Did you really think it was magic?

Would you like to buy Tower Bridge?
 

19 hours ago, Genady said:

What do you think about rolling pandas?

I think they look cute.
But I still don't think any of this really counts as a wheel.

15 minutes ago, Moontanman said:

Yes but tumbleweeds only tumble after they are dead. 

The seeds are alive, and they travel on "wheels"

So, aside from the issue of connecting blood supplies / nerves etc, and the fact that wheels are only useful if you have a "road" and the challenge of finding a use for half a wheel?

... tumbleweed...

I'd be surprised if you can't find some metal recycling place that's prepared to take it.
Nickel is quite valuable.

The Mond process just isn't something that works on a "home brew" scale.

9 hours ago, observer1 said:

In the wiki, it is given that urea reacts with water to form ammonia and CO₂.
CO(NH₂)₂ + H₂O → 2 NH₃ + CO₂

But when I add urea into water, neither is there and gas coming out as CO₂ or any decrease in the level of water
The urea just dissolved. 
How to stop this and make the reaction?

The reaction does happen, but it is very slow.
You can increase the rate of reaction with a suitable catalyst e.g.
https://en.wikipedia.org/wiki/Urease

Why does the thread title say "carbonate"?

1 hour ago, mistermack said:

Then it depends on your body weight etc. If you take the highest number on the chart, 1500 g per hectolitre, you would have to drink about 80 litres of spirit to damage your eyesight. You'd be dead long before your eyes started to suffer. 

OK.
So, without the protective effects of ethanol 30 g of methanol will cause harm.
But a litre of ethanol would probably kill you.
So, as long as the methanol content is less than about 30 grams per litre or 3% the ethanol will kill you before the methanol does any harm.
30 grams per litre 
3000 grams per hectolitre or roughly 2 times higher than the highest figure in the table will be "safe" because of the antidote also being present.

OK, so the table can not be anything to do with health- let's face it, the healthy option doesn't include drinking much hooch.
The reason is that they don't want people adding industrial meths to the authentic product.

You could, realistically get away with adding a bit of meths to something like fruit brandy and blame the methanol of pectin.
You can't do that with gin.
So it's a practical measure of how much methanol indicates that the product has been adulterated.
A quality control issue, rather than a health issue.

What do you think a reasonable "health based" limit would be?

10 hours ago, mistermack said:

It does confirm what I posted earlier, that certain yeasts lead to higher concentrations of methanol in the mash. I don't get why there is such a disparity in the allowed proportions of methanol in the various drinks though. You would think that from a health point of view, the same levels would apply to any drinks. I must be missing something. 

You are missing the fact that the levels are not set on grounds of health.

The methanol content is an indicator of what "good practice" achieves.

Because there's a lot more pectin in some of the substrates than in others, the methanol levels will be higher.

 

4 minutes ago, mistermack said:

On that subject, I don't get why people would pour the first portion away. Methanol surely can be put to use in some way? Like as a fuel for the stove or added to petrol for the car or generator. Pouring it away seems a waste, and would probably leave a tell-tale smell. 

The light fraction is full of acetaldehyde which makes engines knock like hell.
Also, there are miscibility issues with methanol and saturated hydrocarbons.

The distillation ban is on the statute book.

5 minutes ago, dimreepr said:

What you can't do is ban it...

 

They did.

Since a flat mirror is cheap and easy and it would work I guess it's optimal.

Reminds me of selling nuclear shelters...

No dissatisfied customers ever complained.