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Enthalpy - What are the thermodynamic standard conditions?

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Introduction

Enthalpy What are the thermodynamic standard conditions? * 298K, 1 atm pressure, concentration of 1mol per dm3 What is enthalpy change? * The heat change measured at a constant pressure and temperature. Define standard enthalpy of formation: * The enthalpy change when a single mole of compund is formed from its elements under standard conditions of 298K and 1atm pressure with all the reactants in their standard states. Why is enthalpy change for exothermic reactions negative? * Because energy has been released to the surroundings. The products therefore have a lower enthalpy than the reactants and the final enthalpy is less than the initial enthalpy. Classify as endothermic or exothermic: * NaOH dissolves in water & temp. ...read more.

Middle

Organic chemistry Electrophile * A species which seeks out negative centres. Can accept a lone pair of electrons. Nucleophile * A species which seeks out positive centres. Has a lone pair of electrons which can be used to form a dative covalent bond. Radical * A species with an unpaired electron. Are highly reactive. Formed by homolytic fission. Making Alcohol from Alkenes Condensation Reaction * Reagents: concentrated H2SO4 catalyst * Conditions: Room Temperature, then add water and warm under reflux Oxidation Reaction * Reagents: Alkaline Potassium Manganate(VII) solution * Conditions: Room Temp. * Other notes: The manganate(VII) reduces to manganate(VI) and goes from purple to green. Oxidation Reaction 2 * Reagents: O2, silver catalyst * Conditions: 2500C Hydration Reaction * Reagents: steam, H3PO4 catalyst * Conditions: 3000C, 60 atm pressure ...read more.

Conclusion

* Observation with a positive test: Orange preciptate when added to a carbonyl Test for an aldehyde * Reagents: Fehlings solution 1 and 2 * Observation with a positive test: Red precipitate when reagents are warmed with an aldehyde Test for an aldehyde * Reagents: Tollen's reagent (NaOH(aq) + AgNO3(aq) + dilute ammonia solution) * Observation with a positive test: Silver mirror with an aldehyde Test for an alcohol * Reagents: PCl5 in dry conditions * Observation with a positive test: Steamy fumes of HCl gas which turns damp blue litmus paper red Test for a carboxylic acid * Reagents: NaHCO3(aq) * Observation with a positive test: CO2 gas which turns lime water milky Test for an alcohol * Reagents: Na * Observation with a positive test: H2 gas ...read more.

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