Research Melting is the process of changing a solid phase into the liquid. Ice is the solid form of water. It melts and turns back into a liquid when the temperature reaches 32 degrees Fahrenheit (0 degrees C) or above. It is better to find a material to soak up the water that comes out when the ice melts. It is good to do this because water makes the ice melt even faster.
Investigating the effects of salt in ice at room temperature I am going to investigate how the concentration of salt in ice, effects the rate at which it melts. Ice is water frozen into a solid. The molecules in solid ice may be arranged in different ways, called phases, depending on the temperature and pressure. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. The most common phase transition to ice Ih occurs when liquid water is cooled below 0°C.
In this experiment we are going to measure the solubility of KNO3 in water at various temperatures. Results can be reported in different ways ranging from grams or salt dissolving in a milliliter of water to grams of salt in 100 mL of H2O In general, systems tend to go to a state of disorder or to a state of greater entropy. During the dissolving process, the particles of the solid become randomly distributed through the solvent in sharp contrast to their orderly arrangement in the solid state. Ion the solid state there are strong forces holding these particles together. In order to dissolve the solid, energy must be expended to overcome these forces.
The challenge in refrigeration (and air conditioning, etc.) is to remove heat from a low temperature source and dump it at a higher temperature sink. Compression refrigeration cycles in general take advantage of the idea that highly compressed fluids at one temperature will tend to get colder when they are allowed to expand. If the pressure change is high enough, then the compressed gas will be hotter than our source of cooling (outside air, for instance) and the expanded gas will be cooler than our desired cold temperature. In this case, we can use it to cool at a low temperature and reject the heat to a high temperature.
The resulting data showed that it was the chemical reaction of the salt added to the ice that had the fastest melting process. Therefore, in the end our hypothesis which had originally stated that “if we added water to the ice it would melt quicker then adding either air or salt” was proved incorrect. 2 Table of Contents I. II. III. IV.
In addition, when we sweat, the water inside it gains some the heat energy on the skin and evaporates- losing more heat. When the body temperature is back to normal, the hypothalamus shuts off cooling mechanisms. Vasoconstriction Vasoconstriction also needs a stimulus. If the stimulus decreases body temperature, for example, cold surroundings, the hypothalamus sends signals along nerves to activate mechanisms in our body to help it warm up. One of these mechanisms includes- vasoconstriction.
Today, we know that cold also changes how fast the nerves send messages. It lowers the metabolic rate and blood flow in the treated area, and it relaxes the muscles. There are many ways to apply cold to an injury. Some use a simple cold pack, others apply ice directly to the area in a circular motion called "ice massage". (Ingraham 2007) Athletic trainers and physical therapists may recommend an ice bath.
The solubility of solids in a solvent is very dependent on temperature. A solid tends to be more soluble in hot solvents than in cold. This is the reason the crystals precipitate out when the solution is cooled. There are no ideal solvents, however there are a few traits to look for when choosing the best solvent. Those that will dissolve the solute when the solution is hot but not cold.
Some enzymes lose their activity when frozen. Some enzymes denatured when temperature increases too much, a potentially permanent process. Variables: Independent Variable: Temperature, 0°C, 15°C, 35°C, 45°C, 60°C. This is because it is the only thing we are changing over and over in the lab. Dependent Variable: The time taken in seconds the enzyme to react at different temperatures.
Exothermic- Exothermic is when the experiment you’re doing is giving energy out to its surroundings. An exothermic energy diagram looks like the one below… https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTTM1fKKPNCmA_jz1yMYTAHUrSVRYdJpEoGRQUzpNRepRUVy0pE How a cold pack works. The liquid inside the cold pack is water. In the water is another plastic bag or tube containing ammonium-nitrate fertilizer. When you hit the cold pack, it breaks the tube so that the water mixes with the fertilizer.