# Concepts of Heat and Temperature

### Heat and Temperature:

Let's begin by considering the instance below:

If we have water of 100OC in an aluminium cup whose temperature is the same as that of its surrounding; let’s say 22OC; We will observe the followings:

1. The temperature of water inside the aluminum cup will begin to decrease from its initial 100OC.
2. The temperature of the aluminium cup will increase from its previous 22OC.
3. After some period of time, the temperature of water, aluminium cup and the surrounding will become the same.

Note: OC = degree centigrade; and it's a unit of temperature.

For now, think of temperature as the degree of hotness or coldness of a substance or an object with reference to some standard value.

From the above instance, it can be deduced that the heat present in the water molecules are first transferred to the aluminium cup and subsequently to the surrounding.

###### Heat from water >>> Aluminium Cup >>> Surrounding

Meanwhile, understand that aluminium is a metal; and metals are good conductors of heat.

Eventually, the system and the surroundings will reach the same temperature; and the heat transfer ceases. It is at this point, that the water, aluminium cup and the surrounding are said to have reached a thermal equilibrium. This concept of thermal equilibrium is a function of the zeroth law of thermodynamics.

Although the surrounding receives heat from the water and aluminium cup, it is noteworthy to state that the surrounding's temperature may remain approximately unchanged for the following reasons:

1. The volume of air in the surrounding is so large.
You can read on the composition of the atmosphere (Air) here.
2. The water and aluminium will not continue to permanently give out heat energy to the surrounding.
3. Diffusion will continue to occur in the surrounding.

Heat is never lost because it is a form of energy. Instead, it will be transferred according to the first law of Thermodynamics which states that:

Energy can neither be created nor destroyed but can be transferred from one form to another.

You can read on food chain here.

From the above explanations, the transfer of energy (heat energy in this case) from the water to the aluminium cup and finally to the surrounding is referred to as heat.

Heat can simply be explained as an energy that results from the transfer of energy from an object or substance or system with a higher temperature to another with a lower temperature.

Let us consider a reverse instance with regards to heat:

Now, imagine that a cold bottle of water is brought out of the fridge into the kitchen. Assuming the temperature of water is 3OC while that of the kitchen environment is 22OC; the followings will occur:

1. The temperature of the cold bottle of water will start to increase from its initial 3OC.
2. The temperature of the bottle will begin to increase from its initial 3OC.
3. After some period of time, the temperature of the bottle, water and the kitchen surrounding will become the same.

Meanwhile, understand that at no point did the coldness of the bottle or water escaped into the surrounding. Instead it is the temperature of the room that actually caused an increased temperature of the bottle and water (inside the bottle).

In fact, if the temperature of the room was higher than 22OC, heat transfer will be achieved at a much rapid rate; that is, the rate at which the temperature of the water and bottle increases will be faster.

Since heat energy is being transferred from the kitchen surroundings to the bottle and then into the water, we can therefore conclude that heat will always be transferred from a higher region to a lower region until equilibrium is attained.

Heat is never static. It is always transferred and thus; an object will increase its temperature by gaining heat energy from its surroundings while another object simultaneously (at the same time) decreases its temperature by losing its heat energy to the surroundings. For this reason, we may also define temperature as:

The measure or ability of an object or substance to transfer heat energy to another object or substance.

The higher the temperature, the greater the ability of an object or substance to transfer heat. Conversely, the lower the temperature, the greater the tendency of an object to receive the transferred heat.

The point is: 'for heat to be transferred, we must have systems or objects or substances with varying temperatures.

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