# Tag Info

11

$\ce{H2O}$ is not simply split apart by electricity, as you say. No ! What happens on one electrode is not related to what happens to the second electrode. Let's start by discussing what is happening on the negative electrode, the cathode. The negative electrode behaves as if it contains plenty of electrons ready to react with anything able to do it. It ...

6

In electrolysis, why does oxygen only appear on the anode? Easy way to remember this is that oxidation occurs at the anode (both start with vowels), and oxidation implies a loss of hydrogen. If we lose hydrogen from water, we are left with oxygen. If you wish to understand it crudely, the concept is that anode the surface in the solution where the electrons ...

6

Any classification like chemical or a physical change, homogeneous or heterogeneous substance, will eventually fail at one point. From an analytical or physical chemistry's perspective, homogeneous substance is a substance, in a single phase, whose chemical composition is uniform. A heterogeneous substance has different composition from place to place like ...

5

General concept of heterogenity says the matter properties within the given region are location dependent ( within the given resolution and tolerance of the scenario ). The change of these properties can be the gradual ( like a concentration gradient ), abrupt ( like a phase boundary ) or combination of both. Practically speaking, matter is homogenous, if ...

4

Your definition of homogeneity is wrong Homogeneous systems are not, as you seem to assume, about the makeup or constituents of the system being uniform. Homogeneity is about the distribution of the components in the system being uniform. A solution of salt in water is homogeneous (if well mixed) despite having multiple types of molecule in it. If those ...

4

Electron transfer between the 'species in the solution' and the 'electrode' take place at the surface of the electrode. So, considering water with some acid Oxidation at anode: $\ce{2 H2O(l) -> O2(g) + 4 H+(aq) + 4e−} \quad E^\circ = \pu{+1.23 V}$ (for the reduction half-equation) This oxidation (electron transfer from water to the electrode) occur at the ...

3

Esterification $\ce{R_1-COOH + HO-R_2 <=> R1-COO-R2 + H2O}$ has the equilibrium constant, expressed in compound activities: $$K = \frac{a_\mathrm{ester} \cdot a_\mathrm{\ce{H2O}} }{ a_\mathrm{acid} \cdot a_\mathrm{alkohol}}$$ The water activity is decreased by dissolved salts by 2 ways: decreasing the molar fraction of water by dissolved salt ...

2

Why does each atom wait to turn into gas until they reach a particular electrode? There are no oxygen atoms or hydrogen atoms formed in the solution. There is also no "electricity" going through the solution. The processes happen at the electrodes because the cathode is able to provide electrons (to reduce hydrogen ions to dihydrogen) and the ...

2

To get a freezing point depression of $\pu{−1.86 °C},$ the solution should be made by adding $\pu{1 mol}$ organic substance to $\pu{1 L}$ water. And $\pu{1 mol}$ per liter is much. For glucose, it is $\pu{180 g}$ per liter. It is nearly a syrup. I doubt your lake has such a high concentration whatever the nature of the solute. For salts, it is less, because ...

2

Maybe a numerical example will help you. Let's start from pure water, with the following concentrations :$\ce{[H+] = [OH-] = 10^{-7} M}$. Now we will suppose you add $\ce{10^{-7}} mol$ $\ce{HCl}$ in one liter of this water. Suddenly, the concentration of $\ce{H+}$ should double. This is not possible in the long run. A part $a$ of these supplementary $\ce{H+}$...

1

Gardeners often use a tennis ball for this purpose - it preserves a gap in the ice.

1

There are oils sold for swimming pools to slow or stop evaporative cooling . That would be a problem for air breathers like mosquito larva. I don't know anything about it because I went with 1" thick Styrofoam panels. That is what I currently have on my pond ( 10' X 5 '), works very well .I cheat a little and have 150 watt aquarium heater in the 700 ...

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