# Tag Info

## Hot answers tagged heat

19

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 ...

8

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

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 ...

2

Temperature is an intensity , heat is a quantity.

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.

1

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 ...

1

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 ...

1

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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