Biology Coursework Practical – Heat Loss
The aim of this practical is to find to what extent does the surface area to volume ratio of an object affect the rate of heat loss from the object
Hypothesis: As the ratio of surface area to volume of an object decreases the rate of heat loss from the object will also decrease. Objects with the same surface area to volume ratios loose heat at the same rate so long as there are not other variables involved.
Background Knowledge:
The surface area to volume ratio of an object is determined by dividing the surface area by the volume and putting it into a ratio of one.
e.g. A flask of volume 200cm3 and a surface area of 160cm2 will have a surface area to volume ratio of:
160
---- : 1 = 1.25 : 1
200
Objects that are not the same size but have the same surface area to volume ratios loose heat at the same rate. So a flask, with a volume of 200cm3 with a surface area of 160cm2 and a surface area to volume ratio of 1.25:1, will loose heat at the same rate as a similar flask of volume 625 and a surface area of 500 which also has a surface area to volume ratio of 1.25:1. However, generally when you increase the size of an object the surface area to volume ratio decreases so in this example it is very likely that the two flasks in question are different shapes.
In this experiment the two flasks which will be used will different surface area to volume ratios as follows:
100 cm3 flask: Volume = 100, Surface Area = 115. Surface Area to Volume Ratio =
115
---- : 1 = 1.15 : 1
100
500 cm3 flask: Volume = 500, Surface area = 330. Surface Area to Volume Ratio =
330
---- : 1 = 0.66 : 1
500
As it is seen the ratio is lower in the 500 cm3 flask. This means that the rate of heat loss should be less than the 100 cm3 flask.
Heat is lost by three different processes:
* Conduction
* Convection
* Radiation..
Conduction is the process by which heat is transferred from on solid to another. When a solid is heated the molecules inside, which are normally almost static, start to vibrate. When another solid is brought into contact with the heated solid the energy from the vibrating molecules at the edge of the heated solid is transferred to the outer molecules of the other solid.
10cm3 of 1 molar solution. I will use 3 of each solution to ensure that
Materials of different types will exhibit varied changes in temperature when transferred the same amount of heat. This variation is a result of the difference in properties displayed from one material to another, known as "heat capacity." Every substance has a variable, positive valued heat capacity that represents the amount of heat required to initiate a specific temperature change. (Hechinger, page 1) For ideal gases, there are heat capacities at constant volume and constant pressure given by:
When there is a heat exchange between two objects, the object’s temperature will change. The rate at which this change will occur happens according to Newton’s Law of heating and cooling. This law states the rate of temperature change is directly proportional between the two objects. The data in this lab will exhibit that an object will stay in a state of temperature equilibrium, unless the object comes in contact with another object of a different temperature. Newton’s Law of Heat and Cooling can be understood by using this formula:
As the gelatin cube sizes were cut into smaller pieces, the surface area to volume ratio increases. Surface area to volume ration is very important in living organisms, since all the nutrients and oxygen need to diffuse through the cell membrane into the cells. The surface area to volume ratio affects the rate in which the salt diffused through the solution by how the salt diffused out of the gelatin and into the water this relates to small cells that have a faster rate of diffusion for the nutrients and oxygen to diffuse into the cell and out of the cell quicker. Whereas if the cells were bigger, the rate of diffusion for the nutrients and oxygen to diffuse into the cell would take too long and the cell would probably not survive. So the surface area to volume ratio in cells is vital since the smaller they are the faster the rate of diffusion of the nutrients and oxygen can go in and out for the cell to be able to grow and survive.
The total volume of all the liquids will be kept the same. As will the
The porpoise of these is to determine the Specific Heat. Also known as Heat Capacity, the specific heat is the amount of the Heat Per Unit mass required to raise the temperature by one degree Celsius. The relationship between heat and temperature changed is usually expected in the form shown. The relationship does not apply if a phase change is encountered because the heat added or removed during a phase change does not change the temperature.
* Surface Area - This will not affect any of my results, as we are
to find the ratio decidendi in a case. Add to this the fact that there
Volume = Length - (2 * Cut Out) * Width - (2 * Cut Out) * Height
- Suface Area: if you are to change the surface area it is going to
ranging from 50 cm³ of acid and no water, to 12.5 cm³ of acid and 37.5
The process of conduction between a solid surface and a moving liquid or gas is called convection. The motion of the fluid may be natural or forced. If a liquid or gas is heated, its mass per unit volume generally decreases. If the liquid or gas is in a gravitational field, the hotter, lighter fluid rises while the colder, heavier fluid sinks. For example, when water in a pan is heated from below on my stove, the liquid closest to the bottom expands and its density decreases. The hot water as a result rises to the top and some of the cooler fluid descends toward the bottom, thus setting up a circulatory motion. This is also why the heating of a room by a radiator depends less on radiation than on natural convection currents, the hot air rising upward along the wall and cooler air coming back to the radiator from the side of the bottom. Because of the tendencies of hot air to rise and of cool air to sink, radiators are positioned near the floor and air-conditioning outlets near the ceiling for maximum efficiency.
The second part of measuring for volume, we measured the density of Isopropyl alcohol the same way we did for the water. We measured the mass of the empty graduated cylinder which was 46.35 grams and then added 25.0 milliliters of Isopropyl alcohol to it which made the mass 66.95 grams, causing the difference to be 20.6 grams of the Isopropyl. This was 4.4 grams less than what it should have measured out to be.
The ratio for length to width of rectangles is 1.61803398874989484820. The numeric value is called “phi”.
3 Temperature is defined as the measure of the average kinetic energy of the particles of a substance. It is not a form of energy but a means of energy transfer. And since it is an average of the heat or energy therefore the number of particles inside and size of the item don’t matter. It is the physical property emphasizing hot and cold. Generally an object that feels hot will have a high temperature. Or if an object feels warmer to the touch then it’s known that it has to be warmer than body temperature. But other than touch, thermometers are com...