Investigating Water
Water molecules are charged, with the oxygen atom being slightly
negative (d-) and the hydrogen atoms being slightly positive (d+).
These opposite charges attract each other, forming hydrogen bonds.
These are weak, long distance bonds that are very common and very
important in biology.
Water has a number of important properties essential for life. Many of
the properties below are due to the hydrogen bonds in water.
Solvent. Because it is charged, water is a very good solvent. Charged
or polar molecules such as salts, sugars, amino acids dissolve readily
in water and so are called hydrophilic ("water loving"). Uncharged or
non-polar molecules such as lipids do not dissolve so well in water
and are called hydrophobic ("water hating").
Specific heat capacity. Water has a specific heat capacity of 4.2 J,
which means that it takes 4.2 joules of energy to heat 1 g of water by
1°C. This is unusually high and it means that water does not change
temperature very easily. This minimises fluctuations in temperature
inside cells, and it also means that sea temperature is remarkably
constant.
Latent heat of vaporisation. Water requires a lot of energy to change
state from a liquid into a gas, and this is made use of as a cooling
mechanism in animals (sweating and panting) and plants
(transpiration). As water evaporates it extracts heat from around it,
cooling the organism.
Latent heat of fusion. Water also requires a lot of heat to change
state from a solid to a liquid, and must loose a lot of heat to change
state from a liquid to a solid. This means it is difficult to freeze
water, so ice crystals are less likely to form inside cells.
Density. Water is unique in that the solid state (ice) is less dense
that the liquid state, so ice floats on water. As the air temperature
cools, bodies of water freeze from the surface, forming a layer of ice
with liquid water underneath. This allows aquatic ecosystems to exist
even in sub-zero temperatures.
Hess’s Law is also an important concept in this lab. It states that the enthalpy of a reaction is independent of the steps it takes to go from reactant to a product. It happens because enthalpy is a state function. A state function depends on the initial and final state but not the actual process. The Hess’s Law is used to calculate the heat formation of Magnesium Oxide. The amount of heat necessary to create one more mole of a substance is called the Enthalpy of Formation.
It is said that fiction is an essentially rhetorical art and that the author tries to persuade the reader towards a specific view of the world while reading. This is evident in both short stories, A Secret Lost in the Water by Roch Carrier, and He-y Come on Ou-t by Shinichi Hoshi. Although through A Secret Lost in the Water, Roch Carrier displays how fiction is an essentially rhetorical art better than Shinichi Hoshi in He-y, Come on Ou-t (awkard sentence), Shinichi Hoshi demonstrates it better through the use of prognosis. Furthermore, by utilizing the characters, such as the farmer from A Secret Lost in the Water, and the use of symbolism such as the hole from He-y, Come on Ou-t, it is evident that the author makes an endeavour towards persuading
When a substance undergoes a triple point change, then it goes through all three of the states of matter: solid, liquid, as well as gas. When all three matters exist at the same time, it is extremely rare and an interesting sight to experience. A triple point is defined, specifically, as “ the temperature and pressure at which the solid, liquid, and vapor phases of a pure substance can coexist in equilibrium” (1). An excellent example of a substance that has the ability to obtain a triple point would be dry ice. Dry ice is solid CO2. Dry ice has many uses, which include keeping items frozen for a long period of time. This is because dry ice is simple to freeze, stays cold, and has a temperature of “-109.3°F or -78.5°C” (2).
on how long it takes to heat up. If we heat a large volume of water it
Minneapolis,Minnesota - Hold on to your snorkel - WaterPark season is finally here and if the idea of Monster Water Rides has you shaking in your floatation device, your not alone.
water has had equal amounts of time for it to heat up, again I will
A fuel is a substance burned for heat or power. The best type of fuel
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.
Matter exists in three basic states: solid, liquid, or gas. A substance experiences a phase change when the physical characteristics of that substance change from one state to another state. Perhaps the most recognizable examples of phase changes are those changes from a solid to a liquid or a liquid to a gas. When a substance goes through a phase change, there is a change in the internal energy of the substance but not the temperature of the substance (Serway, et al. 611).
Berkeley introduces his water experiment in order to demonstrate that in perception the perceiver does not reach the world itself but is confined to a realm of representations or sense data. We will attempt to demonstrate that Berkeley's description of our experience at the end of the water experiment is inauthentic, that it is not so much a description of an experience as a reconstruction of what we would experience if the receptor organs (the left and right hands) were objects existing in a space partes extra partes. Our argument is that there is nothing in our experience of the illusion to suggest that under normal conditions perception does not reach the world itself.
In this lab, we found the Heat of Vaporization of liquid nitrogen, supported by the data we obtained. First, we calculated the amount of heat absorbed by the 60.00 g of liquid nitrogen we received. To do so, we had to add the liquid nitrogen to a Styrofoam cup containing hot water at 54.3 °C. We took the temperature of the water and nitrogen until it got to its lowest point, 20.2 °C. The water decreased by 31.5 °C after the liquid nitrogen vaporized. The mass decreased as well. After, we found the amount of heat the cup and water released to be 11,400 J, and the measured heat of vaporization to be 191 J/g or 45.6 cals./g. After, we compared this new heat of vaporization with the theoretical value of 199.9 J/g and attained a low negative percent error of -4.5%.
Introduction: A phase change is a result from the kinetic energy (heat) either decreasing or increasing to change the state of matter (i.e. water, liquid, or gas.) Thus saying, freezing is the phase change from a liquid to a solid which results from less kinetic energy/heat. Also, melting is the phase change from a solid to a liquid which results from adding kinetic energy/heat. So, the freezing and melting point of something is the temperature at which these phase changes occur. Therefore, a phase change will occur when a vial of 10 mL of water is placed into a cup of crushed ice mixed with four spoonfuls with 5 mL of sodium chloride for 30 minutes. If 10 mL of water is placed in an ice bath, it will then freeze at 5 degrees Celsius because the kinetic energy will leave quicker with the ice involved. The purpose of this lab is to observe what temperature the water must be to undergo a phase change.
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.
These phases can go from one to another when affected by certain things, which is known as phase changes. To switch from a solid to a liquid, the solid must melt. On the other hand, to switch from a liquid to a solid, freezing must occur. Furthermore, to switch from a liquid to a gas, a process known as evaporation must take place. In contrast, to go from a gas to a liquid, condensation must take place. Furthermore, sublimation must take place for a solid to turn to a gas. Inversely, deposition must occur for a gas to change to a solid.
6. When water is distilled, it does not vaporize all at once when the boiling point is reached. When some water molecules evaporate, the kinetic energy of the remaining liquid goes down and the temperature drops slightly. As a result, the rest of the water needs to be heated again before more molecules of water evaporate. A constant source of heat is needed.