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Determination of the enthalpy change associated with a reaction
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Determination of the Enthalpy Change of a Reaction Determine the enthalpy change of the thermal decomposition of calcium carbonate by an indirect method based on Hess' law. Determination of the Enthalpy Change of a Reaction Determine the enthalpy change of the thermal decomposition of calcium carbonate by an indirect method based on Hess' law. Using the proposed method of obtaining results, these values were gathered: Reaction 1: CaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l) GRAPH ¼ in both cases represents the mean of the data. Using the equation for enthalpy change: H = mcT Where: m = Mass of liquid to which heat is transferred to (g) c = Specific heat capacity of aqueous solution (taken as water = 4.18 J.g-1.K-1) T = Temperature change (oK) We can thus determine the enthalpy changes of reaction 1 and reaction 2 using the mean (¼) of the data obtained. Reaction 1: H = 50 x 4.18 x -2.12 H = -443.08 This value is for 2.51g of calcium carbonate, not 100.1g which is its molecular weight. Therefore: H = -443.08 x (100.1 / 2.51) = -17670.2 J.mol-1. H = -17.67 kJ.mol-1. Reaction 2: H = 50 x 4.18 x -10.3 H = -2152.7 This value is for 1.37g of calcium oxide, not 56.1g which is its relative molecular mass. Therefore: H = -2152.7 x (56.1 / 1.37) = -88150.7 J.mol-1. H = -88.15 kJ.mol-1. Hess' law states that: 1"The total enthalpy change for a chemical reaction is independent of the route by which the reaction takes place, provided initial and final conditions are the same." This means that therefore the enthalpy change of a reaction can be measured by the calculation of 2 other reactions which relate directly to the reactants used in the first reaction and provided the same reaction conditions are used, the results will not be affected. We have the problem set by the experiment: to determine the enthalpy change of the thermal decomposition of calcium carbonate. This is difficult because we cannot accurately measure how much thermal energy is taken from the surroundings and provided via thermal energy from a Bunsen flame into the reactants, due to its endothermic nature. Therefore using the enthalpy changes obtained in reaction 1 and reaction 2 we can set up a Hess cycle: Thus using Hess' law we can calculate the enthalpy change of reaction 3. Reaction 3: H = Reaction 1 - Reaction 2 H = -17.67 - (-88.15) = +70.48 kJ.mol-1. Comparing the value +70.
This is by using the same mass and realizing that the specific heat of both the regular water and the hot water are the same. In our procedure, 100 mL of hot water was mixed with 100 mL of the regular water; therefore, the masses in Equation 3 cancel out (the densities of the water at different temperatures aren’t exactly the same, but the difference is negligible). This leads to the change in temperature of the hot water equaling the negative change of temperature in the regular water, shown as:
The reaction between the sugar in the gummy bear and the melted potassium chlorate in this experiment is an example of an exothermic reaction. An exothermic reaction is a chemical reaction that releases energy as heat or light. When potassium chlorate is melted, it produces potassium chloride and oxygen. When the sugar and oxygen react, energy accumulated in the chemical bonds of the sugar molecules is released. This is a combustion reaction, an exothermic process in which a substance reacts specifically with oxygen to produce heat, water, and carbon dioxide. During the process of combusting the sugar in the gummy bear with oxygen, the products formed are heat, a purple flame (light), carbon dioxide, and water.
Investigating the Rate of Reaction Between Marble Chips and Hydrochloric Acid I am investigating the rate of reaction between marble chips (calcium
Thermochemistry is the study of the heat associated with chemical reactions and physical processes heat changes that accompany physical and chemical processes. (textbook) During the first portion of this lab the caloric content of a snack food was found by burning it and measuring how much heat was released. For the second part of this lab, a styrofoam calorimeter was used to measure the specific heat of an unknown metal and that information was used to identify the sample. A calorimeter is a tool used in thermochemistry can be used to measure the heat exchanged between the system and surroundings for a variety of reactions.
Experiment is to investigate the rate of reaction between hydrochloric acid and calcium carbonate Hydrochloric acid + Calcium Carbonate Þ Calcium Chloride + Water + Carbon Dioxide 2HCl (aq) CaCo3 (s) CaCl2(s) H2O (aq) CO2 (g) There are a number of variables in this experiment and these are listed below as input variables and outcome variables.
= 3 ´ E(C-H) + 1 ´ E(C-O) + 1 ´ E(O-H) + 1.5 ´ E(O=O)
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=
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.
NaOH(aq)Â Â Â Â Â Â Â Â +Â Â Â Â Â Â Â Â Â HCl(aq)Â Â Â Â Â Â Â Â Â Â Â Â Â Ã Â Â Â Â Â Â Â Â Â Â Â Â NaCl(aq) Â Â Â Â Â Â + Â Â Â H2O(l).
be yes as I will then be able to use enthalpy change of reaction to
The aim is to find out if changing the concentration of the hydrochloric acid solution has an effect on the time taken for the reaction. The reaction that will take place is: Hydrochloric acid + Calcium Carbonate + Calcium Chloride + Water + Carbon dioxide 2HCl (aq) + CaCo3 (s) CaCL2 (aq) + H2O + CO2 (g). Collision theory - Collisions between reactant particles are needed. for the reaction to take place in order to form a product.
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.
Hydrochloric acid + calcium carbonate arrow calcium chloride + carbon dioxide + water. HCl(aq) + CaCO3(s) arrow CaCl2(aq) + CO2(g) + H2O(l) Things that affect the reaction rate of this experiment are: 1. The temperature of the hydrochloric acid. 2.
The Effect of Temperature on the Rate of Reaction Between Hydrochloric Acid and Calcium Carbonate
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,