equation 5 -1 equation 5-2 qreaction =-qcalorimeter Hreactionreaction/mOlimiting

Question

equation 5 -1 equation 5-2 qreaction =-qcalorimeter Hreactionreaction/mOlimiting reagent As discussed in the previous lab, AHcalorineter can be calculated as calorimeter mwater X Swater x ATwater equation 5-3 Prelab/practice questions: 1. The enthalpy of solution of a 50.0 g aqueous solution was measured in a calorimeter. During the measurement, the temperature of the calorimeter contents (the solution) increased from 25.00 to 27.41°C. Assume the specific heat of the calorimeter (solution) contents is the same as the specific heat of water (4.184 J/g-oC). Assume you have 1 mole of the solute. a. Use equation 5-3 to calculate qakrineter during the dissolution. b. Use equations 5-1 and 5-2 to calculate H 1 on in k mol from the value ofq k r obtained in the preceding step. c. From the sign of the value obtained in step b, determine whether the dissolution reaction is exothermic or endothermic.

Explanation / Answer

part a

Given mass of water = 50g

specific heat of water = 4.184J/g.C

delta T = T final - T initial

= 27.41-25 = 2.41 C

Thus q calorimeter = mass of water x specific heat of water x delta T

= 50g x 4.184J/g.C x 2.41 C

= 504.172 J

Part B

From eq. 1

- q calorimeter = q reaction

Thus q reaction = -504.172 J

Delta H solution = q reaction / 1 moles of solute

As it is given that the amount of solute dissolved = 1 mole

delta H solution = -504.172 J/mol

Part C

As the sign of delta H and Q are negative the dissolution is exothermic. (temperature is increased)

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