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Unformatted text preview: calorimetry - measurement of heat flow • calorimeter- device used to measure heat flow • heat capacity- amount of heat needed to raise temperature by 1°C o molar heat capacity - heat capacity of 1 mol of a substance • specific heat- heat capacity of 1g of a substance o specific heat = quantity of heat transferred / (grams of substance x temperature change) o = q / (m x DT) • q = specific heat x grams of substance x DT Find amount of heat needed to warm 250 g of water from 22°C to 98°C • Given: o specific heat of water = 4.18 J/g-K • change in K same as change in °C • q = specific heat of water x grams of water x DT • = 4.18 J/g-K x 250g x 76K • = 7.9 x 104 J constant-pressure calorimetry - heat gained by solution same as heat lost by reaction • qsoln = specific heat of solution x grams of solution x DT = -qrxn Find enthalpy change for reaction if temperature of solution in calorimeter changed from 21.0°C to 27.5°C when Find enthalpy change for reaction if temperature of solution in calorimeter changed from 21....
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This document was uploaded on 10/30/2011 for the course CHEM 161 at Rutgers.
- Spring '08