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Specific heat capacity physics lab report
Calorimetry lab report heat capacity
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Experiment to Compare the Enthalpy Changes of Combustion of Different Alcohols Introduction: This plan will try to outline how the experiment of comparing changes of combustion of different alcohols will be conducted and what results are expected. Background When chemical reactions take place they are often accompanied by energy changes. Chemical reactions most frequently occur in open vessels. That is, they take place at constant pressure. Enthalpy refers to energy at constant pressure (volume may vary). Enthalpy: An example is best to illustrate to show enthalpy works. Methane - how much energy does its molecules contain? The first thing needed is the amount of methane present = 1 mole (16 g). What ever its value, the total amount of energy in a given amount of a substance (sometimes called the Heat energy content) is known as the enthalpy, denoted H. Methane is a fuel to get energy from it, react it with oxygen. CH4(g) + 2O2(g) CO2(g) + 2H2O(l) The above chemical equation shows that 2 moles (64 g) of oxygen molecules are required to burn 1 mole of methane. Again, it is impossible to know the total enthalpy (heat energy content) of the oxygen. Likewise, we can't know the total heat energy content of 1 mole of CO2 and 2 moles of H2O (the products). Enthalpy Change H = (HCO2 + 2HH2O) - (HCH4 + 2HO2) In general, H = Hproducts - Hreactants But remember, this is theoretical; it is not possible to determine the absolute value of the enthalpy of a chemical element or compound. However, H values for chemical reactions can be obtained. They can be measured experimentally, or calculated using Hess's Law (see later), or worked out in other ways. Exothermic and Endothermic Reactions When chemical reactions take place they are often accompanied by heat changes. The system (the reactants which form products) may give out heat to the surroundings, causing them to warm up. In this case the reactants have more stored energy (greater total enthalpy) than the products. Such chemical reactions are said to be exothermic. The system may take heat from the surroundings, causing them to cool down. In this case the reactants have less stored energy (less total enthalpy) than the products. Such chemical reactions are said to be endothermic. Exothermic reactions give out energy to the surroundings. Endothermic reactions take energy from the surroundings. Most reactions take place at constant pressure... It is possible to measure changes in heat energy that accompany chemical reactions. Most reactions take place in vessels that are open to the atmosphere, that is, they take place at constant pressure (volume may vary). The special name given to a change in heat energy content measured at constant pressure is enthalpy change.
From working out how much fuel has been used, I can work out how much bond energy has been released from the molecules of the alcohol. From those results I will be able to say which alcohol is the best for combustion and which one is the worst to combust. A good fuel should produce a lot of heat energy and use a small amount of fuel. (economical) A bad fuel uses a lot of fuel and produces less heat energy.
one gram of water by 1ºC. I chose to use water because it is safe,
= 3 ´ E(C-H) + 1 ´ E(C-O) + 1 ´ E(O-H) + 1.5 ´ E(O=O)
water has risen to 60°c I will then put the lid on the spirit burner
In this experiment, a lit candle was placed in jars to prove if more oxygen in the present environment would affect the duration of the flame. During the experiment, a burning candle was put in three differnent sized jars labled, ‘A’, ‘B’, and ‘C’ from smallest to largest in their order. The flame was then measured to determine how long it lasted in the individual jars. If more oxygen is present in the environment, then a fire will last longer. The hypothesis that a lit candle will last longer with more oxygen is supported by the acquired data because the flame had lasted significantly longer (a differnece of of approximately 26 seconds) in Jar C than Jar B. This is also similar when comparing the duration of the flame in Jar B and Jar
The Enthalpy Change of Different Alcohols My aim is to compare the enthalpy change of combustion of different alcohols in relation to the structure of each molecule. The enthalpy change of combustion of a fuel is a measure of the energy transferred when one mole of the fuel burns completely. In a chemical reaction, bonds must either be made or broken, this involves an enthalpy change. The formation of bonds is exothermic, energy is lost to the surrounding; on the other hand, breaking bonds is endothermic, energy is taken in. I obtain the value for the enthalpy change of each fuel by using the formula: Energy transferred from the fuel=
Given that, the breakdown of methane in an oxygen-rich atmosphere creates carbon monoxide, along with water vapor, and infrared radiation. However, carbon monoxide is not stable and will become carbon dioxide, in a short amount of time. Additionally, this process releases more infrared radiation. Infrared radiation, for the most part, is invisible and comes off as heat; you can experiment with this by putting
During this reaction the solution gained heat. This is what we were monitoring. The reason why the solution gained heat is because the reaction lost heat. Energy is lost when two elements or compounds mix. The energy lost/ gain was heat. Heat is a form of energy as stated above in the previous paragraph. The sign of enthalpy for three out of the four reactions matches what was observed in the lab. For the last reaction, part four, the reaction gained heat not the solution like parts one through three. The negative enthalpy value for part four indicates that the reaction gained
This software enables you to simulate experiments. This means that I am able to quickly carry out experiments to help in planning for my investigation. ---------------------------------------------------------------------- Alcohol Temperature Increase (oC) Mass of burner before exp. (g) Mass of burner after exp.
Incomplete combustion occurs when a fuel reacts with oxygen to produce carbon monoxide (CO), water (H2O) and carbon (C). This form of combustion releases less energy from the reaction that complete combustion, as it does not consume the fuel entirely. The chemical equation for incomplete combustion of acetylene gas is:
The oxygen atom is joined to the hydrogen atom as well as the carbon atom, which makes the oxygen a part of a hydroxyl group. These atoms are generally part of a hydrocarbon chain. These alcohols can take away water from the body, in which a hydrocarbon chain has replaced a hydrogen atom. Alcohols have a general structure of CnH2n+1OH. The aim of this investigation is to see the link between the number of carbon atoms in a fuel with the amount of energy it releases.
In order for a system to gain energy the surroundings have to supply it, and visa versa when the system looses energy the surroundings must gain it. As the energy is transferred it can be converted form its original form to another as the transfer takes place, but the energy will never be created or destroyed. The first law of thermodynamics, also known as the law of conservation of energy, basically restates that energy can’t be destroyed or created “as follows: the total energy of the universe is a constant.” All around the conservation of energy is applied. When gasoline burns in the engine of a car, an equal amount of work and heat appear as the energy is released. The heat from the engine warms its surroundings, the cars parts, the air, and the passenger area. The heat energy is converted into the electrical energy of the radio, chemical energy of the battery, and radiant energy of the lights. The change in the sum of all of the energies formed from the burnt gasoline would be equal to the “…change in energy between the reactants and products.” Biological processes, like photosynthesis, also follow energy conservation. The green plants convert the radiant energy emitted by the Sun into useful chemical energy, such as the oxygen that we breathe. The energy transferred between any surroundings and any system can be in the form of various types of work, chemical, mechanical, radiant, electrical, or heat.
to see when the x marked paper is not visible. I repeatedly did this 3
that the rate of reaction must be fast enough to make as much of the
To answer the most obvious question, what is ΔHºrxn·? Well, ΔHºrxn· means the change in enthalpy. To break it down further, enthalpy is the measure of the amount of energy in a system. Every single reaction in the entire universe has a change in enthalpy. Energy is held in each and every single bond that puts together the world we see and live in today. When a reaction takes place and bonds are broken and reconnected, energy has been transferred, and enthalpy tells us how much. It is just about nearly impossible to measure all of the energy that there is out there, but scientists can measure how much energy has been transferred through the system. It would be like trying to measure the volume of the ocean, pretty much impossible, huh? But,