Heat Capacity and Calorimetry
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Questions and Answers

What is the correct definition of heat capacity?

  • The amount of heat required to raise the temperature of one gram of a substance.
  • The amount of heat required to raise the temperature of a given quantity of the substance by one degree Celsius. (correct)
  • The total energy stored in a substance at a given temperature.
  • The temperature at which a chemical reaction occurs.

    • Heat is always transferred from a cooler body to a warmer body.

    False

    What is the formula used to calculate the quantity of heat absorbed or released?

    q = m x Cs x (Tf - Ti)

    In an exothermic reaction, heat is ______ and the temperature of the surroundings will ______.

    <p>released, increase</p> Signup and view all the answers

    What units are used for specific heat?

    <p>All of the above</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Heat = Transfer of energy due to temperature difference Calorimeter = Device used to measure heat transfer Enthalpy of reaction = Total heat of a chemical reaction at constant pressure Specific heat = Heat required to raise 1g of substance by 1°C</p> Signup and view all the answers

    In a calorimeter, heat can be either gained or lost to the surroundings.

    <p>False</p> Signup and view all the answers

    What type of chemical reaction absorbs heat?

    <p>Endothermic reaction</p> Signup and view all the answers

    What does the negative sign in the equation -qhot = qcold + qcal signify?

    <p>Heat is lost by hot water.</p> Signup and view all the answers

    The heat of solution for infinite dilution involves a small amount of solvent.

    <p>False</p> Signup and view all the answers

    What are the three steps in the solvation process?

    <p>Breaking of bonds between solute molecules, breaking of intermolecular attractions between solvent molecules, formation of new solute-solvent attractive bonds.</p> Signup and view all the answers

    The heat of solution is expressed in _____ per mole.

    <p>kJ</p> Signup and view all the answers

    Match the following steps in the solvation process with their corresponding energy changes:

    <p>Breaking solute bonds = Require and absorb energy Breaking solvent bonds = Require and absorb energy Forming solute-solvent bonds = Release energy</p> Signup and view all the answers

    What occurs during an exothermic heat of solution?

    <p>Temperature of the system increases.</p> Signup and view all the answers

    Energy is absorbed in both breaking solute and solvent bonds.

    <p>True</p> Signup and view all the answers

    The equation for heat lost by hot water can be written as - m.Cs.(T3 – T2) = m.Cs.(T3 - T1) + C (T4 - T1) where C represents _____ energy gained by the calorimeter.

    <p>heat</p> Signup and view all the answers

    What is the primary product of the reaction between a strong acid and a strong base?

    <p>Water and salt</p> Signup and view all the answers

    The heat of neutralization is always positive.

    <p>False</p> Signup and view all the answers

    What is the heat evolved when one equivalent of a strong acid and one equivalent of a strong base react?

    <p>13.7 kcal/mol</p> Signup and view all the answers

    When a solute is added to a solvent, the solution process is characterized as __________.

    <p>endothermic</p> Signup and view all the answers

    Match the following reactions with their heat of neutralization:

    <p>HCl + NaOH = -13.7 kcal/mol HCl + KOH = -13.7 kcal/mol H2SO4 + NaOH = -14.0 kcal/mol HCl + NH3 = -10.5 kcal/mol</p> Signup and view all the answers

    Which of the following represents the correct equation for calculating the heat of solution?

    <p>qsolution = qwater + qcal</p> Signup and view all the answers

    The heat gained by cold water is equal to the heat lost by the calorimeter.

    <p>True</p> Signup and view all the answers

    The specific heat of water is denoted as __________.

    <p>Cs</p> Signup and view all the answers

    What is the result of the reaction between hydrochloric acid and sodium hydroxide?

    <p>HCl + NaOH → NaCl + H2O</p> Signup and view all the answers

    Sodium and chloride are active participants in the reaction between hydrochloric acid and sodium hydroxide.

    <p>False</p> Signup and view all the answers

    What is the formula used to calculate the number of moles in 50 mL of a 2.5 M solution?

    <p>moles = concentration (mol/L) x volume (L)</p> Signup and view all the answers

    The heat of neutralization is defined as the heat change when one mole of acid and one mole of base react to form _____ and _____.

    <p>water, salt</p> Signup and view all the answers

    Match the following concepts with their definitions:

    <p>Heat of neutralization = The heat change during the reaction of acid with base Heat of displacement = The heat change when one mole of metal is displaced by another Spectator ions = Ions that do not participate in a chemical reaction Oxidation = The loss of electrons in a chemical reaction</p> Signup and view all the answers

    What is the heat change when one mole of Zn displaces a mole of Cu from CuSO4?

    <p>It is an exothermic process.</p> Signup and view all the answers

    The reverse reaction of zinc displacing copper from CuSO4 is possible.

    <p>False</p> Signup and view all the answers

    The reaction ____ + ____ → ____ is an example of an oxidation-reduction process involving zinc and copper sulfate.

    <p>Zn, CuSO4, ZnSO4 + Cu</p> Signup and view all the answers

    What is the purpose of recording the temperature every 30 seconds in the first step of the procedure?

    <p>To determine when the temperature is stable</p> Signup and view all the answers

    The temperature T4 represents the highest temperature recorded during the experiment.

    <p>False</p> Signup and view all the answers

    What should be done with the iron piece after polishing and before inserting it into the calorimeter?

    <p>Weigh the iron piece using a two-digit balance.</p> Signup and view all the answers

    The specific heat of ____ is required to calculate the specific heat of the iron in the experiment.

    <p>water</p> Signup and view all the answers

    Match the temperature readings with their corresponding significance:

    <p>T1 = Initial temperature of cold water T2 = Stable temperature of hot iron T3 = Temperature after inserting iron into calorimeter T4 = First drop in temperature of the mixture</p> Signup and view all the answers

    What is the primary reason zinc can displace copper in a reaction?

    <p>Zinc has a greater tendency to lose electrons.</p> Signup and view all the answers

    Magnesium metal can displace copper in a reaction.

    <p>True</p> Signup and view all the answers

    What is electropositivity?

    <p>The ability of metals to lose electrons.</p> Signup and view all the answers

    Specific heat (Cs) is measured in ____/g°C or ____/gK.

    <p>J</p> Signup and view all the answers

    Which of the following is the method to determine the limiting agent?

    <p>By comparing the number of moles of reactants.</p> Signup and view all the answers

    Match each term with its definition:

    <p>Electropositivity = The ability to lose electrons Specific heat = Heat required to raise temperature by one degree Calorimetry = Measurement of heat changes Molarity = Concentration in moles per liter</p> Signup and view all the answers

    The units for specific heat are the same for temperature in Celsius and Kelvin.

    <p>True</p> Signup and view all the answers

    What is the purpose of the lab described in the content?

    <p>To determine the specific heat of several metals using calorimetry.</p> Signup and view all the answers

    Study Notes

    Heat Capacity of a Calorimeter

    • Heat (q) is the transfer of energy due to temperature difference.
    • Heat capacity (C) is the amount of energy needed to raise the temperature of a substance by 1°C.
    • Specific heat (Cs) is the amount of energy needed to raise the temperature of 1 gram of a substance by 1°C.
    • Units for heat capacity are J/°C or J/K.
    • Units for specific heat are J/g°C or J/gK.

    Chemical Reactions and Calorimeters

    • Calorimeters are insulated devices used to measure heat transfer during chemical reactions.
    • Exothermic reactions release heat, increasing the system's temperature.
    • Endothermic reactions absorb heat, decreasing the system's temperature.
    • Enthalpy of reaction (ΔH) is the total heat absorbed or released at constant pressure.

    Heat of Solution

    • Heat of solution is the change in heat content when one mole of solute dissolves in a solvent.
    • Enthalpy of solution (ΔH) measures heat absorbed or released when forming a solution.
    • The process involves breaking bonds in solute and solvent, and forming new bonds between solute and solvent.
    • If heat is absorbed, the process is endothermic, otherwise exothermic.

    Heat of Neutralization

    • Heat of neutralization is the heat released/absorbed in the reaction of an acid and base.
    • Strong acids and alkalis have close values of heat of neutralization.
    • This is because the reaction involves free ions (H+ and OH−) reacting to form water.

    Heat of Displacement

    • Heat of displacement is the heat change from a more reactive metal taking a less reactive metal's place in a salt solution.
    • The more reactive metal displaces the less reactive one, as it has a stronger tendency to lose electrons.
    • A reaction is an oxidation-reduction process: one substance loses electrons, the other gains them.

    Specific Heat of Metals

    • Specific heat (Cs) is the amount of heat needed to raise the temperature of one gram of a substance by 1°C.
    • Purpose of lab is to determine specific heat of metals.
    • Procedures involve measuring water/metal temperature changes.
    • The heat lost by the metal is gained by the water and the calorimeter.

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    Determination of the Heat Capacity of a Calorimeter PDF

    Description

    This quiz covers the concepts of heat capacity, specific heat, and calorimetry. It delves into exothermic and endothermic reactions and the heat of solution. Test your understanding of how these principles apply to chemical reactions and energy transfer.

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