The heat capacity of an object indicates how much energy that object can absorb
ID: 477449 • Letter: T
Question
The heat capacity of an object indicates how much energy that object can absorb for a given increase in that object's temperature. In a system in which two objects of different temperatures come into contact with one another, the warmer object will cool and the cooler object will warm up until the system is at a single equilibrium temperature. Note the difference between the terms molar heat capacity, which has units of J/(mol middot^degree C), and specific heat, which has units of J/(g middot^degree C). A volume of 125 mL of H_2O is initially at room temperature (22.00^degree C). A chilled steel rod at 2.00^degree C is placed in the water. If the final temperature of the system is 21.50^degree C, what is the mass of the steel bar? Use the following values: specific heat of water = 4.18 J/(g middot^degree C) specific heat of steel = 0.452 J/(g middot^degree C) Express your answer to three significant figures and include the appropriate units. The specific heat of water is 4.18 J/(g middot^degree C). Calculate the molar heat capacity of water. Express your answer to three significant figures and include the appropriate units.Explanation / Answer
Mass of 125 ml of water is Mw =density of water *water =1g/ml*125 ml =125g
From bomb calorimetre formula
Heat lost by water = heat gained by rod
=>Mw*Cpw*(Tw-T) =Mr*Cpr*(T-Tr)
Where T=final system temperature
=>125*4.18*(22 - 21.5) =Mr*0.452*(21.5-2)
=>Mr =261.25 /8.814= 29.64 g
B) for converting specific heat of water from mass to molar, we have to change gram to mole
=4.18 J/(g.K)=4.18 J/(g.K)*18g/mol =75.24 J/mol.K
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