September 26, 2022, 11:53:44 AM
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High School Chemistry Forum / Re: Can someone help with this question?
« Last post by Aldebaran on Today at 11:45:16 AM »
Yes it can be answered but I don’t think the question is written very well.
High School Chemistry Forum / molecular formula of compound
« Last post by auksas on Today at 11:23:10 AM »
Kerosene contains 86% of carbon and 14% of hydrogen. Calculate the volume of air for burning
80 g of kerosene

I tried to find molecular formula but after calculation of empirical formula I'm stuck...I think that the next step is to use chemical equation to solve the problem, but I can't find how.
I am well outside of my comfort zone, but I am willing to hazard a guess.  There is a difference between relative energy levels and absolute energy levels.  Does that help?
Citizen Chemist / Re: How to delay change of color of a reaction?
« Last post by Illusionist on Today at 09:33:50 AM »
My question is different from the other (the ingredients are completely different), and by the way, some kind of clock reactions CAN be delayed (the coloration), by simply adding distilled water.

This is why it's called "Clock reaction". Am i correct?

I am asking if, with this reaction too, is possible to do the same, in some way.

Have a nice day
Generic Discussion / Re: Introduce Yourself
« Last post by Enthalpy on Today at 07:28:49 AM »
Just storing here my avatar.
Your question puzzled me. Germany consumed 130TWh of natural gas in January 2022, mostly for heating
so 1GW over 1 year saves 9TWh or 2 January days worth of natural gas.

Natural gas costs 15€/TJ (0.05€/kWh) at the border
so 1GW over 1 year lets save 0.5G€/year, which is indeed better than nothing.

Or you can compare with a present lengthy and passionate debate in Germany about closing TWO nuclear power plants right now, or in January, or keeping them in operation longer. The unhealthily wasted sucrose is ONE power plant worth.

Though in my view, it's better to sell or give the food to hungry people than burning it.


What's your geothermal system? Do you have a hot source, or do you use the ground's inertia for heating and cooling, combined with a heat pump maybe?
By differentiating the energy (1/R) over the distance, you get the force (1/R2).
Hi Adi,

I can't tell if all the sodium polyacrylate dissociates. It depends on the amount of water.

A hydrogen bond happens between neutral species, for instance between two water molecules. Here the carboxylate and the sodium ions are charged, this makes a stronger bond with the polar water molecules. It resembles closely the dissolution of NaCl in water, where Na+ attracts the negatively polarized side of H2O and Cl- the positively polarized side. If water is in small amount, it resembles the dessication by CaCl2. The difference by sodium polyacrylate is that the negative ion remains a long polymer chain.

Both ions attract water. But since all + ions can't separate from all - ions due to the huge attraction, only the sum of both effects is observed.
High School Chemistry Forum / Re: Can someone help with this question?
« Last post by Enthalpy on Today at 05:40:29 AM »
Can the question be answered? I feel it lacks something like "both reactants are completely consumed".
A cyclotron for 500MeV protons isn't that big: D=6.6m H=2.9m on the appended sketch - unless beam focussing brings other constraints.

115kA per small lukewarm copper coil consume only 59kW together, while accelerating the protons for 1mol/year neutrons draw some 1.2MW at the plug. Bigger coils would reduce the 59kW or let increase the gap.

730t Fe cost ~1M€, as little as 100kW over 5 years.

A smaller cyclotron needs more than 1.8T, hence without iron, and the consumption jumps. 4T at the centre need 2×2.2MA. Pure Al at 20K and 60kOe resists 76pΩ×m, so each coil dissipates 52kW at 20K, and the cooler evacuates 5.6MW: as expensive in a month as iron costs once. The power is only proportional to the induction since the dimensions vary too. 6T at the rim limit the coils' size, which I didn't check as it won't improve much the consumption.

Maybe superconductors do that better, I can't tell. The unshielded field remains badly dangerous.

Marc Schaefer, aka Enthalpy
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