CHEM 01LA Lecture Notes - Lecture 6: Heat Capacity, Calorimetry, Jmol

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20 May 2018

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CHEM 01LA Experiment 6: Calorimetry

●Experimental Purpose

○The purpose of this experiment is to use a simple calorimeter to calculate the

specific heat capacity of a metal

●Calorimeters

○Calorimeter: a device used to measure the heat absorbed or evolved during a

process

■Contains insulating walls to prevent heat exchange between calorimeter

contents and the surroundings

●Specific Heat Capacity

○Specific heat capacity (specific heat): the quantity of heat required to raise the

temperature of one gram of a given substance by 1℃ (or 1K) at constant pressure

■q = cp * m



* ΔT

●cp = specific heat capacity (subscript indicates constant pressure)

●q = quantity of heat that must be added to effect a temperature

change to a certain substance with mass m

●Amounts of heat are measured in joules

○The specific heat capacity of water is 4.18J/(g*℃)

■Also equal to 1 cal/(g*℃)

●Determination of Specific Heat Capacity

○Step 1



: Heat weighted metal to some known temperature

○Step 2



: Place metal into a calorimeter that contains a measured amount of water at

a known temperature

■Heat flows from metal to the water (both will reach the same temperature)

■Heat lost by the metal = amount of heat absorbed by water

●qmetal = -qwater

○qwater = cp(water) * mwater *ΔTwater = -cp(metal) * mmetal * ΔTmetal

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Document Summary

The purpose of this experiment is to use a simple calorimeter to calculate the specific heat capacity of a metal. Calorimeter : a device used to measure the heat absorbed or evolved during a process. Contains insulating walls to prevent heat exchange between calorimeter contents and the surroundings. Specific heat capacity (specific heat): the quantity of heat required to raise the temperature of one gram of a given substance by 1 (or 1k) at constant pressure. Q = c p * m * t. C p = specific heat capacity (subscript indicates constant pressure) Q = quantity of heat that must be added to effect a temperature change to a certain substance with mass m. Amounts of heat are measured in joules. The specific heat capacity of water is 4. 18j/(g* ) Step 1 : heat weighted metal to some known temperature. Step 2 : place metal into a calorimeter that contains a measured amount of water at a known temperature.

Related Questions

When 0.595 g of biphenyl (C12H10) undergoes combustion in a bomb calorimeter, the temperature rises from 25.4 âC to 29.9 âC.

Part A

Find ÎErxn for the combustion of biphenyl in kJ/mol biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/âC.

Part B

Learning Goal: To understand the concepts of heat capacity, specific heat, and molar heat capacity. Heat capacity, C, is the amount of energy required to raise the temperature of a substance by exactly 1 degree Celsius. The energy needed to warm an object increases as the mass of that object increases. We see this in our everyday life. For example, we know that it takes much more energy to heat a large tank of water than a small cup. Because of this dependence on mass, experimentally determined heat capacities are always reported in terms of the amount of the substance that is heated. One method is to report how much energy it takes to raise the temperature of one mole of a substance by exactly 1 degree Celsius. This value is the molar heat capacity, which has the symbol Cp.The molar heat capacity is given in the units J/(molâ âC). A second method is to report how much energy it takes to raise the temperature of one gram of a substance by exactly 1 degree Celsius. This value is the specific heat, which has been given the symbol Cs. The units for specific heat are J/(gâ âC). The heat capacity of a substance is therefore related to the energy q needed to raise its temperature by an amount ÎT. That is, q=nCpÎT, where n denotes the number of moles of the substance, or q=mCsÎT, where m denotes the number of grams of the substance.

Part 1

It takes 55.0 J to raise the temperature of an 9.90 g piece of unknown metal from 13.0âC to 24.8 âC. What is the specific heat for the metal?

Express your answer with the appropriate units.

Part 2

The molar heat capacity of silver is 25.35 J/molâ âC. How much energy would it take to raise the temperature of 9.90 g of silver by 16.0 âC?

Express your answer with the appropriate units.

Part 3

What is the specific heat of silver? Express your answer with the appropriate units.

pearcockroach968

A coffee-cup calorimeter of the type shown in Figure 5.17 contains 150.0 g of water at 25.1 °C. A 121.0-g block of copper metal is heated to 100.4 °C by putting it in a beaker of boiling water. The specific heat of Cu(s) is 0.385 J/g-K. The Cu is added to the calorimeter, and after a time the contents of the cup reach a constant temperature of 30.1 °C.
(a) Determine the amount of heat, in J, lost by the copper block. (b) Determine the amount of heat gained by the water. The specific heat of water is 4.18 J/g-K. (c) The difference between your answers for (a) and (b) is due to heat loss through the Styrofoam^® cups and the heat necessary to raise the temperature of the inner wall of the apparatus. The heat capacity of the calorimeter is the amount of heat necessary to raise the temperature of the apparatus (the cups and the stopper) by 1 K. Calculate the heat capacity of the calorimeter in J/K. (d) What would be the final temperature of the system if all the heat lost by the copper block were absorbed by the water in the calorimeter?

byzantiumswan321

A coffee-cup calorimeter contains 130.0 g of water at 25.3 âC . A 124.0-g block of copper metal is heated to 100.4 âC by putting it in a beaker of boiling water. The specific heat of Cu(s) is 0.385 J/gâ K . The Cu is added to the calorimeter, and after a time the contents of the cup reach a constant temperature of 30.3 âC .

Part A

Determine the amount of heat, in J , lost by the copper block. (3350 J)

Part B

Determine the amount of heat gained by the water. The specific heat of water is 4.18 J/gâ K . (2720 J)

Part C

The difference between your answers for (a) and (b) is due to heat loss through the StyrofoamÂ® cups and the heat necessary to raise the temperature of the inner wall of the apparatus. The heat capacity of the calorimeter is the amount of heat necessary to raise the temperature of the apparatus (the cups and the stopper) by 1 K . Calculate the heat capacity of the calorimeter in J/K .

Express your answer using two significant figures.

Part D

What would be the final temperature of the system if all the heat lost by the copper block were absorbed by the water in the calorimeter?

CHEM 01LA Lecture Notes - Lecture 6: Heat Capacity, Calorimetry, Jmol

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