teachin X menthakeCovalentActivity do?locator assignment-take&takeAssignmentsess

Question

teachin X menthakeCovalentActivity do?locator assignment-take&takeAssignmentsessionLocator;#assignment-t Use the References to access important values if needed for this question. When a solid dissolves in water, heat may be evolved or absorbed. The heat of dissolution (dissolving) can be determined using a coffee cup calorimeter In the laboratory a general chemistry student finds that when 2.58 g of NH,CIO(s) are dissolved in 117.10 g of water, the temperature of the solution drops from 24.32 to 22.72 °c The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.59 Jioc Based on the student's observation, calculate the enthalpy of dissolution of NH,CI04(s) in kJ/mol Assume the specific heat of the solution is equal to the specific heat of water. kJ/mol AHdissolation Retry Entire Group 4 more group attempts remai Submit Answer

Explanation / Answer

Heat lost by apparatus = Heat lost by water + Heat lost by calorimeter

=> 117.10g * 4.184J/gC * (24.32-22.72)C + 1.59J/C * (24.32 - 22.72)C

=> 786.458 J

Molar mass of NH4ClO4 = 117.49 gm/mol

Number of moles of NH4ClO4 = Mass/molar mass = 2.58/117.49 = 0.021959 moles

Delta H dissolution = (Heat lost)/(number of moles) = 786.458/0.021959 = 35814.8 J = 35.8 kJ/mol

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