Investigating the Heat Loss of Water From a Beaker

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INVESTIGATING THE HEAT LOSS OF WATER FROM A BEAKER

INTRODUCTION:

There are many factors that influence the effectiveness of the three main forms of heat loss, conduction, convection and radiation.

These include:

* The starting temperature of the water,

* Mass of the water,

* Surface area of the water,

The three main forms of heat loss are:

Radiation: This is the loss of energy, in this case heat energy, through the atmosphere via electromagnetic waves. (This gives it the ability to travel through a vacuum, i.e. the sun shining through space to Earth.) When this energy reaches an object it is absorbed by it. The energy absorbed causes particles in the object to vibrate, and so it heats up. The hotter an object is, the more energy it has and therefore more radiation will occur. Also the larger the surface area of an object, the more energy it will radiate.

Dull coloured objects radiate more energy than shiny objects so we will try to test this to if it has an effect.

Convection: Convection is the expansion of particles when they are heated. When a substance like water is heated, the particles within the substance expand and become less dense that normal.

Due to this decrease in density the particles rise through the substance, and at the surface of the water some of the particles evaporate. As more water evaporates, more and more energy is lost and so the water cools down and when evaporation occurs the object that the substance is evaporating off cools. (This is shown well when you get out the shower and you feel cold because the water is evaporating off of you). When the particles move away from the heat source or are so expanded that the particles are not passing heat from one to another, the particles cool. When they cool they compress back to their original density, which causes them to fall to the bottom of the water. As they are now tightly packed they heat is conducted from one particle to another and they heat, expand, rise, cool and so on as the cycle continues. This cycle is called a convection current. This convection current is shown in the diagram below.

Conduction: This is when heat energy is passed from one atom to the next via vibrations within a substance. When an atom comes in contact with a heat source it gains kinetic energy, which causes it to vibrate. When a vibrating atom hit another atom it passes energy on it, which causes that atom to vibrate also. This process happens all the way along a substance, so if the heat source is large enough, then the entire object will heat up.

This process occurs in all substances, but in some better than others. In metals conduction is particularly effective. This is due to the large amount of 'free electrons' in all metals that are able to pass on the energy and vibration quickly because there are to many of them so close together. Insulators, like foam, do not conduct well because they do not have many free electrons to carry the charge and their atoms are quite spread and so the energy cannot be passed on so efficiently and a lot of the energy is lost. The diagram below shows the process by which energy is passed on by vibrations in a substance.
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Aim:

The aim of this investigation is to find out which of the three types of heat loss, Convection, Conduction and Radiation, is the major cause of loss of heat from a calorimeter of hot water.

Prediction:

I think that radiation will be the least dramatic cause of heat loss in this experiment. This is because we are using calorimeters that have a shiny silver coating on the outside, and bright shiny surfaces are poor radiators. This means not much heat will be lost by radiation. Also for radiation to be effective the substances ...

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