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Chapter 6
Thermochemistry (Test 3)
| Question | Answer |
|---|---|
| thermodynamics | the study of energy and its transformations |
| thermochemistry | the study of the relationship between chemical reactions and energy |
| energy | the capacity to do work |
| heat | the flow of energy caused by a temperature difference |
| work | the result of a force acting through a distance |
| What is the equation for work involving force and distance? | w = F times d |
| What is the equation for work involving pressure and volume? | w = - P (delta V) |
| kinetic energy | the energy associated with the motion of an object |
| What is the equation for kinetic energy? | Ek = (1/2)(m)(V^2) |
| potential energy | stored energy; energy due to position or composition (examples: chemical energy) |
| thermal energy | energy associated with the temperature of a substance |
| chemical energy | energy associated with the relative positions of electrons and nuclei in atoms and molecules |
| system | the part of the universe being studied |
| surroundings | everything else in the universe |
| internal energy of the system (E) | the sum total of all of the kinetic and potential energies of every particle in the system; unknowable |
| state function | a function that is independent of the history or path followed |
| What are some examples of state functions? | temperature, volume of a gas, location, molarity, internal energy, enthalpy, and change in any of these. |
| What is one joule equal to? | 1 (kg * m^(2))/(s^(2)) |
| What is the First Law of Thermodynamics? | the law of conservation of energy; the total energy of the universe is constant. |
| What is the equation that expresses the First Law of Thermodynamics? | delta E = q + w, where delta E is the change in internal energy, q is heat, and w is work. |
| How do you determine if the sign of q is positive or negative? | q is positive if heat flows from the surroundings to the system; q is negative if heat flows from the system to the surroundings. w is positive if the surroundings do work on the system; w is negative if the system does work on the surroundings. |
| calorimetry | measuring heat flow |
| calorimeter | an instrument used for measuring heat flow |
| bomb calorimeter | a constant volume calorimeter delta E = q sub v, where q sub v is heat flow under constant volume |
| coffee-cup calorimeter | a constant pressure calorimeter delta H = q sub p, where q sub p is heat flow under constant pressure |
| heat capacity | the amount of heat required to raise the temperature of a substance by 1 degree Celsius |
| specific heat capacity | the amount of heat required to raise the temperature of 1 g of a substance by 1 degree Celsius |
| What is the equation for heat? | q =(m)(c)(delta T) |
| When a problem involves two substances, how do you determine heat? | -q = q |
| In a bomb calorimeter (constant volume), what equation is used? | delta E = q sub v |
| How many joules are equal to 1 liter*atmosphere? | 101.3 J = 1 L*atm |
| delta H | enthalpy change; heat flow under constant pressure |
| An endothermic reaction has which sign of delta H? | positive |
| An exothermic reaction has which sign of delta H? | negative |
| The stoichiometric coefficients in a thermochemical reaction refer to what? | the number of moles of reactants and products |
| A reversed reaction has what effect on the delta H of that reaction? | changes the sign |
| The enthalpy change, delta H, is for what? | the specified number of moles |
| What is Hess's Law? | the total enthalpy change (delta H) for a process is the same regardless of whether the process occurs in one step or many steps |
| What is a formation reaction? | forming one mole of a substance from its elements in their most stable forms |
| Any element in its most stable form has what enthalpy of formation? | 0 |
| To find delta H of a reaction using delta H of formations, always do what? | delta H formation of products - delta H formation of reactants |
Created by:
2nenogirl
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