Chemical changes as a result of heating Essay

When a solid is dated the particles gain energy and start to vibrate faster and faster. Initially the structure is gradually weakened which has the effect of expanding the solid. Further heating provides more energy until the particles start to break free of the structure. Although the particles are still loosely connected they are able to move around. At this point the solid is melting to form a liquid. The particles in the liquid are the same as in the solid but they have more energy. To melt a solid energy is required to overcome the attractions between the particles and allow them to pull them apart.

The energy is provided when the solid is heated up. The temperature at which temperature a material is a solid, liquid or gas depending on its melting temperature. Anything with a melting temperature higher than about CHIC is likely to be a solid under normal conditions. Materials have widely differing melting temperatures e. G. Mercury -CHIC, ice CO, salt 10810C, aluminum CHIC and steel 1 CHIC. Everyday materials such as ice, butter and wax have different melting temperatures and can be used as examples with children.

Ice is probably the melting substance most children are familiar with. It can be problematic when trying to develop an understanding of melting as it does often appear to them to melt without any source of heat. Ice melts at room temperature because the surrounding air is warmer than the ice and at a temperature above the melting temperature. The heat energy required to melt the ice comes from the surrounding air which will consequently become a little cooler. Not all solids melt when they are heated. Some may undergo chemical changes as a result of heating.

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For example paper burns rather than melts. Heat is a measure of Energy. When a substance is heated, its articles gain energy. This energy makes the particles in a gas or liquid move around faster. In a solid, the particles vibrate more rapidly. Source 3- http://cooperativeness’s. Bloodspot. Co. UK/2012/08/geese-physics- revision. HTML This energy is measured on an absolute angle. (This means it can’t go lower than zero, because there’s a limit to how slow particles can move. The unit of thermal energy is measured in Joules 0). Temperature is a measure of Hotness.

The hotter something is, the higher its temperature. Temperature is usually measured in co (degrees Celsius), but there are there temperature scales, like OF (degrees Fahrenheit). Energy tends to flow from hot objects to cooler objects – e. G. Warm radiators heat the cold air in your room. The bigger the temperature difference, the faster the heat is transferred. If there’s a difference in temperature in tow different places, then energy will flow between them. If you heat up water on a stove, the water will never get hotter than CHIC.

You can carry on heating the water up, but the temperature won’t rise. You need to put in Energy to break Intermolecular Bonds. When you heat a liquid, the heat energy sakes the particles move faster. Eventually, when enough of the particles have enough energy to overcome their attraction to each other, big bubbles of gas form in the liquid – this is boiling. In a solid, heat energy makes the particles vibrate faster until eventually the forces between them are overcome and the particles start to move around – this is melting.

When a substance is melting or boiling, you’re still putting in energy, but the energy used for breaking intermolecular bonds rather than raising the temperature. Source 4-http://www. Monopolies. Com/dc/science/encyclopedia/changing-states. HTML When solid, the particles of a substance are tightly packed together, making it rigid. A substance can change from a solid state to a liquid state, and from a liquid state to a solid state. Substance in a liquid state can change to a solid state and also to a gas state. Particles in a gas are spread out and free to move around. This is why gases fill all the space around them.

A substance that is a gas can change to a liquid, and a liquid substance can change to a gas. Source 5- http://www. Newton. Deep. Anal. Gob/ASCII/scheme/checkmate. HTML Heat moves from a warmer body to a cooler body. Thus heat moves from the drink to the ice. When heat moves from the drink, it gets cooler. Heat is a transfer of energy on a microscopic scale. Temperature is a measure of the average kinetic energy (energy of motion) of the molecules present in a sample of matter. Thus, when heat moves from the drink, the molecules in the drink have a lower kinetic energy.

Microscopically, the flow of heat between two phases is a massive transfer of kinetic energy due to molecular collisions. Now, if you dropped a block of cold aluminum into a cup of warm water, ALL of the heat that flowed from he “warm” water to the “cold” block would correspond to a “slowing-down” of the water molecules (cooling) and a “speeding-up” of the aluminum block’s atoms (warming). Nothing else happens in this situation, because the amount of energy transferred is not enough to break the covalent bonds holding the atoms in the block of aluminum together.

Now, if the cold block is ice instead of aluminum, the heat that flows into the ice IS enough to break the hydrogen bonds holding the molecules in the block of ice together… Or at least, some of it. Whether the ice melts completely will depend on owe much water and how much ice there is in the glass… But some of it will melt, and this allows a cube of ice dropped into the cup to absorb more heat than the same mass of liquid water at the same temperature would… Uh, as Jade hawk says, to the “latent heat of melting. ” So some cooling is due to melting, and some to equilibration. Souse 6- http://hypersonic. Pay-astral. Gus. Du/habeas/thermo/ice. HTML The cooling of a drink with a cube of ice is more effective than using cold water because of the energy extracted from the drink to melt the ice (heat of fusion). The cooling of a notation of water with a mass of ice at O C illustrates the energy of the phase change and the approach to thermal equilibrium.

The molecules of H2O behave differently in water than in ice. In water they are floating around freely and in ice they are “stationary”, they only vibrate slowly. This is because they don’t have enough energy to break their intermolecular bonds. So in order to melt ice you need to add energy to give the molecules kinetic energy to move around, becoming less bonds and the ice melts to ice. The cooling of a drink with a cube of ice is more effective than using cold water because ice can absorbs a lot more heat.


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