Essays Tagged: "Enthalpy"

Evaluating an enthalpy change that can not be measured directly

Chemistry Experiment.Dr. Watson.Evaluating An Enthalpy Change That CannotBe Measured Directly.Introduction.We were told that sodium hydrogencarbon ... late as part of the experiment.This however cannot be measured directly, but can be found using the enthalpychanges from two other reactions. These being that of sodium hydrogencarbonate andhydrochlor ... bonate.Calculations.From these results I had to calculate deltaH2 and deltaH3. DeltaH2 refers to theenthalpy change when sodium hydrogencarbonate reacts with hydrochloric acid, anddeltaH3 is the entha ...

(2 pages) 49 0 3.9 Jan/1996

Subjects: Science Essays > Chemistry

The enthalpy change of combustion for the alcohol homologous series.

I am going to investigate the enthalpy change of combustion for the alcohol homologous series. I will investigate how alcohols wit ... hol homologous series. I will investigate how alcohols with increasing number of carbons affect the enthalpy change when an alcohol goes under combustion.The energy that alcohols release when being us ... hen an alcohol goes under combustion.The energy that alcohols release when being used is called the enthalpy change of combustion. This is defined as"Standard enthalpy change of combustion, is the ent ...

(19 pages) 95 1 3.5 Apr/2003

Subjects: Science Essays > Chemistry

The heat of combustion for one mole of alcohol.

will also be comparing the experimental molar heat of combustion with the theoretical, using bound enthalpy's.Background informationI have found some information that will help me with my experiment. ... !6xC=O8xH-OSo using data tables we can look up then average bond enthalpies from, and calculate the enthalpy change of the reaction.Bond TypeAverage bond enthalpy /kJ mol-1C-H+413C-C+347O=O+498C=O+805 ...

(7 pages) 35 0 0.0 Nov/2003

Subjects: Science Essays > Chemistry

Heat of Formation

(2 pages) 31 0 3.0 Jul/2004

Subjects: Science Essays > Chemistry

Combustion Of Alcohols

can be shown in an energy level diagram: Reaction co-ordinate ?H is the heat content, which is the enthalpy, which is negative in exothermic reactions as the diagram shows that energy is 'lost' as he ... rried out directly at a constant pressure, the heat flow is exactly equal to the difference between enthalpy of products and that of the reactants", or: Qp = Hp - Hr = ?H Where Qp is the heat flow at ...

(9 pages) 36 0 3.3 Jan/2005

Subjects: Science Essays > Chemistry

Thermochemistry

primarily concerned with the following state functions defined in thermodynamics:Internal energy (U)Enthalpy (H).Entropy (S)Gibbs free energy (G)Most identities in Thermochemistry arise from applicati ... ken up in such processes. Since reactions are often carried out at constant pressure, the change in enthalpy is the appropriate measure of heat given off or absorbed.Laws of Thermochemistry1. The magn ...

(3 pages) 20 0 0.0 Mar/2005

Subjects: Science Essays > Chemistry

Thermochemistry

primarily concerned with the following state functions defined in thermodynamics:Internal energy (U)Enthalpy (H).Entropy (S)Gibbs free energy (G)Most identities in Thermochemistry arise from applicati ... ken up in such processes. Since reactions are often carried out at constant pressure, the change in enthalpy is the appropriate measure of heat given off or absorbed.Laws of Thermochemistry1. The magn ...

(3 pages) 28 0 0.0 Mar/2005

Subjects: Science Essays > Chemistry

A Lab experiment on how to determine the enthalpy change of the decomposition of Calcium Carbonate

The Enthalpy Change of the Decomposition of Calcium CarbonateIntroductionResearch Question:What is the e ... nResearch Question:What is the enthalpy change of the decomposition of calcium carbonate?Background:Enthalpy in chemistry can be thought of as the energy contained within the bonds, or the internal en ... reaction is exothermic and the products are more stable than the reactants and vice versa. But, the enthalpy, or change in energy, of some reactions are too difficult to carry out in a standard labora ...

(2 pages) 13 0 0.0 May/2007

Subjects: Science Essays > Chemistry

A comparison between the Enthalpy of formation of MgO acquired via a series of reactions and Hess's Law (will they be equivalent?)

Enthalpy of FormationBackgroundThe enthalpy of formation (ΔH°f) is defined as the heat cha ... hat are formed. Thus, in order to acquire the desired results, one must use Hess's Law in which the enthalpy of a series of reactions are measured and added together to give the final answer of the en ... together to give the final answer of the enthalpy of formation.In this situation, to determine the enthalpy of formation for MgO is very difficult in the laboratory (Mg(s) + ½ O2 (g) ( MgO(s)) ...

(2 pages) 2955 0 0.0 May/2007

Subjects: Science Essays > Chemistry

Hotpack Cold Pack Lab

aCl2) needed to cause a 60-degree temperature rise for 200 ml of water.-To calculate standard molar enthalpy values of each compound.Procedure: The first thing that needed to be done was measure out 2 ...

(2 pages) 10 0 3.0 Feb/2008

Subjects: Science Essays > Chemistry

Hess's Law

m: To carry out three experiments where we will calculate the development of heat and the change in enthalpy by measuring the change in temperature in different substances. By doing so, it will give u ... ;t2.7 °C2Mass of solution (kg): m0.2 kgHeat (kJ) = W (4200 x m x Δt)2268 J = 2.268 W (kJ)3Enthalpy change (kJ/mol NaOH) = ΔHA40141.59292 J/mol ≈ 40.1 kJ/mol4Reaction B: NaOH (aq) ...

(4 pages) 1918 0 0.0 Sep/2008

Subjects: Science Essays > Chemistry

Enthalpy and Potential Energy - Study Notes

ing apart (the relative positions of the ions changed)-any change in potential energy → called enthalpy change (in this case, exothermic – energy is released)NaOH (s) → NaOH (aq)Potenti ... this case, exothermic – energy is released)NaOH (s) → NaOH (aq)Potential Energy change = enthalpyEnthalpy – the potential energy change that a system undergoes, reflected by a change i ...

(3 pages) 11 1 0.0 Jan/2009

Subjects: Science Essays > Chemistry

Enthalpy Of Solution Lab Report Assessed on: * Data Collection and Processing (DCP) * Conclusion and Evaluation (CE)

Usman Omid Chemistry IB 1A Enthalpy Of SolutionIntroductionAimThe aim of this investigation was to determine the enthalpy of th ... Hydroxide (NaOH) in water (H2O).TheoryWhen a solid ionic compound is dissolved in water a change of enthalpy is involved. The enthalpy of a solution, ΔHsol is the enthalpy change when one mole o ... eg;C = 292KThe uncertainty = ±1KTemprature = 292K ± 1 KTo find the uncertainty in the enthalpy change, the uncertainties of the other values must be considered. Since in the calculation ...

(8 pages) 31 1 5.0 Mar/2009

Subjects: Science Essays > Chemistry

General Chemistry

was 58.7g. So, the calculated atomic mass was very close to the true one.The experimental change in enthalpy for part 3 was 28.6 kJ/mol while the true change in enthalpy was slightly lower at 27.0kJ/m ... 27.0kJ/mol. These two numbers are fairly close together. In part 4 however the calculated change in enthalpy was -55.53 kJ/mol while the experimental change was very far off at -7.7 kJ/mol. The change ...

(1 pages) 0 0 0.0 Oct/2013

Subjects: Science Essays > Chemistry