General Chemistry II: Enthalpy Change
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Questions and Answers

What is the primary definition of energy in the context of thermodynamics?

  • The energy of random motion associated with temperature change
  • The energy resulting from the interaction of charged particles
  • The ability to cause motion of an object against a force
  • The capacity to do work or transfer heat (correct)

    • What is the equation that defines kinetic energy?

  • Ek = mv^2 (correct)
  • E = mc^2
  • Eel = Q1Q2 / d
  • Q = cd

    • What type of energy is associated with the interaction of charged particles?

  • Thermal energy
  • Electrostatic energy (correct)
  • Potential energy
  • Chemical energy

    • What occurs when bonds are formed in a chemical reaction?

    <p>Energy is evolved</p> Signup and view all the answers

    What is the definition of heat in the context of thermodynamics?

    <p>The form of energy that brings about temperature change when transferred</p> Signup and view all the answers

    What type of energy is stored within the structural units of chemical substances?

    <p>Chemical energy</p> Signup and view all the answers

    What is the unit of heat capacity?

    <p>J/°C or J/K</p> Signup and view all the answers

    What is the amount of heat energy required to raise the temperature of one gram of a substance by 1 °C?

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

    What is the formula to calculate the quantity of heat absorbed by an object?

    <p>heat = (mass) × (specific heat capacity) × (temp. change)</p> Signup and view all the answers

    If 100 g of water requires 1000 J of heat energy to raise its temperature by 1 °C, how much heat energy would be required to raise the temperature of 200 g of water by 1 °C?

    <p>2000 J</p> Signup and view all the answers

    Why does 1000 J of heat energy raise the temperature of 100 g of sand by 12 °C, but only raise the temperature of 100 g of water by 2.4 °C?

    <p>Because the heat capacity of an object depends on the type of material</p> Signup and view all the answers

    What is the molar heat capacity of a substance?

    <p>The amount of heat energy required to raise the temperature of one mole of a substance by 1 °C</p> Signup and view all the answers

    What is the specific heat of water in joules per gram-kelvin?

    <p>4.18 J/g-K</p> Signup and view all the answers

    What is the equation that relates the heat transferred to the mass, specific heat, and temperature change?

    <p>q = m x Cs x ΔT</p> Signup and view all the answers

    What is the purpose of using a coffee-cup calorimeter in this experiment?

    <p>To determine the enthalpy change for the reaction</p> Signup and view all the answers

    What is the acid-base reaction that occurs when mixing HCl and NaOH?

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

    How is the total heat produced in the reaction calculated?

    <p>Using the equation q = m x Cs x ΔT</p> Signup and view all the answers

    What is the first step in solving the problem of calculating the enthalpy change for the reaction?

    <p>Calculate the number of moles of HCl and NaOH involved</p> Signup and view all the answers

    What is the temperature change in the reaction of the acid with the base?

    <p>6.5°C</p> Signup and view all the answers

    What is the unit of the specific heat capacity Cs in the equation?

    <p>J/g–K</p> Signup and view all the answers

    What is the value of the enthalpy change per mole of HCl in the reaction?

    <p>-54 kJ/mol</p> Signup and view all the answers

    What is the significance of the negative sign of the enthalpy change ΔH?

    <p>The reaction is exothermic.</p> Signup and view all the answers

    What is the purpose of the bomb calorimeter in measuring the enthalpy change of a reaction?

    <p>To measure the internal energy change of the reaction.</p> Signup and view all the answers

    What is the relationship between the enthalpy change ΔH and the internal energy change ΔE in a bomb calorimeter?

    <p>ΔH is approximately equal to ΔE.</p> Signup and view all the answers

    What is the product of the combustion of methylhydrazine?

    <p>N2(g), CO2(g), and H2O(l)</p> Signup and view all the answers

    What is the initial temperature of the calorimeter in the experiment?

    <p>25.00 C</p> Signup and view all the answers

    What is the heat capacity of the calorimeter?

    <p>7.794 kJ/ C</p> Signup and view all the answers

    What is the temperature change of the calorimeter during the experiment?

    <p>14.50 C</p> Signup and view all the answers

    What is the heat evolved for the combustion of the 4.00-g sample of methylhydrazine?

    <p>-113.0 kJ</p> Signup and view all the answers

    What is the goal of the problem?

    <p>To calculate the heat of reaction for the combustion of a mole of CH6N2</p> Signup and view all the answers

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