# Tag Info

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Adding more fuel doesn't permit an arbitrarily high combustion temperature because of an unavoidable intrinsic limitation: The reaction has to heat its products. (In the case of wood, this is mostly carbon dioxide and water.) In the most efficient flame, we might mix the reactants in perfect proportion and eliminate heat losses as best we can, but we can't ...

9

I agree with Chemodynamics, and I will try to add a different perspective (or maybe two). The fire process is a process where you add a fuel (i.e. energy in the system), and that fuel is gradually consumed. The rate at which it is consumed releases the chemical energy. An interesting thing here is that: the log is a three dimensional object the fire will ...

6

In engineering terms heat (energy) and temperature are two different things. One (of many) real life examples is the kitchen stove. When you turn on the kitchen, (and leave it at a set point), the kitchen will provide thermal energy (heat) at a constant rate. However if you put a pan onto the kitchen stove you will see that its temperature rises initially ...

5

We define reactions uniquely depending on the reactants and products. Here are examples related to your question. Formation: Na(s) + (1/2)Cl$_2$(g) $\rightarrow$ NaCl(s) Lattice Formation: Na$^+$(g) + Cl$^-$(g) $\rightarrow$ NaCl(s) Solution: NaCl(s) $\rightarrow$ NaCl(aq) Hydration: Na$^+$(g) $\rightarrow$ Na$^+$(aq) Atomization: Na(s) $\rightarrow$ Na(g) A ...

5

A little example: Water has a specific heat capacity (SHC) of 4.2 kJ.kg-1.K-1. I have a 2.1 kW electric kettle. $$\Delta T = \frac {P \cdot t}{m \cdot SHC}$$ where $\Delta T$ is the temperature rise, $P$ is power (kW), $t$ is time and $m$ is mass (kg). If I run the kettle for 60 s I will put $2.2 \times 60 = 132 \ \text{kJ}$ (energy) into the water. If ...

4

The very first thing to check is the sharpness of the bit tip. a dull bit will not drill worth a d*mn and just waste your battery power. Note that it only takes one brief encounter with something hard to wreck the tip of a drill bit. Bits are cheap compared to your time- go out now and buy a sharp one, or get your bit resharpened! Cordless electric drills ...

4

Brass is a natural choice for accomodating sliding or rotating contact with steel surfaces. This is because oxide grit or metal particles which would cause galling get embedded into the (softer) brass instead of peeling material off of both sliding surfaces, as commonly happens when the sliding surfaces are made of the same material (bad design choice!). ...

4

I think a review of the definition of specific heat will help: Specific heat is the amount of energy required to raise one gram of a pure substance by one degree Centigrade. $C_P = \frac {Q}{m\Delta T}$, $Q = Amount$ of $heat$ $m = Mass$ $T = Temperature$ of the $substance$ The specific heat is a constant for each specific material, and the formula can be ...

3

In the steady-state case you describe, the thermal conductivity determines how much heat (kW) a material will trasnmit per unit surface for a given temperature difference (K). In heat exchanger applications, the thermal conductivity is one of three heat transfers in series: primary medium to pipe, transfer through pipe, pipe to secondary medium. To my best ...

2

Temperature is an intensity , heat is a quantity.

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It's unlikely that you'll be able to find a coating of any sort that insulates the item from thermal changes as a result of holding it. How does one prevent an element from melting at 85 °F? Enclose it in a cooling chamber, perhaps a Peltier effect device providing lower temperatures within the transparent cylinder.

1

What you're asking for is a perfect insulator. There is no perfect insulator, let alone a thin film liquid kind. If ambient temperature is even on iota higher than the melting temperature, eventually it will reach that and melt. If the magic spray you're looking for existed you could make ice cubes that would never melt at room temperature, or super ...

1

A suspended ceiling at a height of 2.4m is the most efficient way of saving the heating cost. Because right now most of the heat in your home goes up to the high ceiling. If you don't have access to supplies or dry-wall (gypsum-board), you can hang a lightweight frame of boards of 4cm by 4cm lumber and cover them with plastic. this photo is a typical ...

1

Example Since the rest of the answer is too long I will start with an example. Imagine you could build a heat exchanger from wooden pipes. If you run through the liquid you would observe very little efficiency (i.e. the hot liquid would remain hot and the cold cold). There would be too little heat exchange, because the wood would not allow heat to pass ...

1

I didn't realize how confusing the terms could be for a heat exchanger until I started typing it out: I will refer to the hot side as: the side where fluid leaves cooler than it enters the side that ends up being cooled the side that heat flows out of I will refer to the cold side as: the side where fluid leaves hotter than it enters the side that is ...

1

IMHO you are still confusing heat with temperature (despite the answer to this question or this ). My Q is why does increased motion or mass of molecules contribute to heat , increased temperature. I will try to answer in a way that address that fundamental difference. Consider 1 kg of water in a well insulated vessel which is travelling with 10[m/s]. ...

1

I prefer this definition for Hf: "The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states." Simply put though heat of formation is a tool we use to quickly calculate heat of ...

1

Figure 1. The phase diagram for water. The pressure and temperature axes on this phase diagram of water are not drawn to constant scale in order to illustrate several important properties. Image source: Chem.LibreTexts.org. The situation you are describing is circled in Figure 1. You are travelling along the horizont line through the melting point of water ...

1

Keep adding heat to water when it is at 100 deg C causes a phase change but no more temperature change.

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Our categorization systems and atomic models are all an approximation, but they help relate the things we can't see to things we can visualize and understand. We define a chemical reaction as one where chemical "bonds" are altered. This is where electron configurations between atoms are altered. While electrons are technically indistinguishable ...

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Adding more wood does not change the temperature at which wood burns, but it does give you more heat. Think of it this way: a 15,000 BTU furnace may heat a small apartment, but you'll need a 100,000 BTU furnace to heat a house. They both burn natural gas at the same temperature, the latter just burns more of it at the same time. So the air coming out of ...

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At the instantaneous moment of stopping the Container, there will be a rush of the molecules of the rear end to the front end. After some time, $\delta t$ this rush will cause extra pressure on the front of the container and less pressure on the back of the container until there is an equilibrium and the rush stops. Therefore at the time $t= \delta t$ there ...

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One basic notion behind this is that temperature of a substance is defined as the average kinetic energy of all the atoms or molecules of that substance. Now assume gas in a balloon. Also assume that the balloon is not moving, so the average velocity of the gas inside the balloon is zero. Despite the average velocity (as a vector average) being zero, the ...

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