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The heat flow (per unit area) through some thin layer, e.g. a boundary layer of water, is given by: $$ \frac{dQ}{dt} = \frac{K\Delta T}{d} $$ where $K$ is the thermal conductivity, $d$ is the thickness of the layer and $\Delta T$ is the temperature difference between the two sides of the layer. So a high thermal conductivity does indeed mean a high heat ...


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The equation: $$ dS = \frac{dQ}{T} $$ only applies to reversible processes. For an irreversible process $dS \gt dQ/T$. To see this start with the expression for the change in internal energy: $$ dU = dQ - dW $$ The internal energy is a state function, so this equation always applies whether the process is reversible or irreversible. So for a reversible ...


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The sign is governed by the convention - whether the volume is of your system in consideration or not. If you decrease the volume of your system - you increase the energy of your system, so you require for total energy change to be positive. If the volume is describing your system then $ dV <0 $ and so $dE=-PdV>0$ is the correct expression If the ...


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In some high-demand medical facilities, liquid oxygen at cryogenic temperatures (in tanks) is used (http://208.76.246.34/~ava/Oxygen-source.pdf). More often, gaseous oxygen in metal cylinders is used. The pressure may vary, but the above source gives 13700kPa (for UK).


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The answer depends on the nature of the "huge oxygen bottles"... You often see large ( around two stories high) tanks outside a hospital. They are distinguished by the name of the chemical firm, Union Carbide or Linde among others, painted on the side, and by the thick layer of frost found on the attached plumbing. These tanks hold liquid oxygen at low ...



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