Question | Answer |
Thermodynamics is __ | The study of energy, work, and heat. |
A system contains __ | the process under study |
Surroundings are | the rest of the universe |
First law of Thermodynamics | Energy of the universe is constant |
Another name for the first law of thermodynamics is | The law of conservation of energy |
Every chemical bond is really __ | stored chemical energy |
Bonds must __ for a reaction to occur | break |
Breaking bonds requires __ | energy |
When energy from a system is released into its surroundings, this is called an __ reaction. | exothermic |
When energy from a system's surroundings is released into the system, this is called an __ reaction | endothermic |
If the energy required to break a chemical bond is __ than the energy released when the bonds are formed, there is a net __ of energy. This is a __ reaction. | less, release, exothermic |
If the energy required to break a chemical bond is __ than the energy released when the bond is formed, there will be an __ __ of energy. This is a __ reaction. | larger/greater, external supply, endothermic |
If the equation ends with +#kcal (or C), it is __. | exothermic |
If the equation begins with #kcal (or C), it is __. | endothermic |
Enthalpy represents __ | heat energy |
The energy difference between the products and reactants of a chemical reaction is __ | enthalpy |
When energy is __, the enthalpy charge is __. (As in -#kcal or -C.) This is an __ reaction. | released, negative, exothermic |
When energy is __, the enthalpy charge is __. (As in +#kcal or +C. )This is an __ reaction. | absorbed, positive, endothermic |
When a reaction occurs without any external energy input, it is a __ reaction. | spontaneous |
Most __ reactions are spontaneous. | exothermic |
__ is used to predict if a reaction will occur. | Thermodynamics |
Besides thermodynamics, another factor used to predict whether a chemical reaction will occur or not is called __. | entropy |
Exothermic reactions are always __. | negative |
T or F: Fuel oil burned in a furnace is an example of an endothermic reaction. | false, it's exothermic |
The 2nd Law of Thermodynamics says that __ | the universe spontaneously tends toward increasing disorder or randomness |
Entropy is __ | a measure of the randomness of a chemical system |
When a system has high entropy, that means it is __ | highly disordered, or lacking a repeating and regular pattern |
When a system has low entropy, that means it is __ | well organized. It may have a crystalline structure. |
There is no such thing as __ entropy. | negative |
A positive (+) ΔS means an __ in the disorder of the reaction. | increase |
A negative (-) ΔS means a __ in the disorder of the reaction. | decrease |
Name 3 processes that have positive entropy. | melting, vaporization, dissolution (they all have a +ΔS) |
If a reaction is exothermic and has a +ΔS, then it is __ | spontaneous |
If a reaction is endothermic and has a -ΔS, is is __ | nonspontaneous |
If a reaction is not endothermic or exothermic, then it is spontaneous or nonspontaneous based on the relative size of __ and __. | ΔH and ΔS |
Gas has __ entropy than water. | greater or more (gas is highly disorganized) |
A solid has __ entropy than water. | less (solids are highly organized) |
Free energy is represented by a __ | ΔG |
Free energy represents the __ | combined contribution of the enthalpy and entropy values for a chemical reaction |
Free energy predicts __ of chemical reactions | spontaneity |
Negative ΔG is always __ | spontaneous |
Positive ΔG is always __ | nonspontaneous |
In an equation, the letter T stands for __ | temperature in Kelvin |
What do you need to know to predict the sign of ΔG of a reaction? | ΔH and ΔS |
Calorimetry is the __ | measurement of heat energy changes in a chemical reaction |
A calorimeter is a __ | device which measures heat changes in calories |
The change in temperature measured by a calorimeter is used to measure the __ | loss or gain of heat |
In an exothermic reaction, heat that has been released is __ | absorbed |
In an endothermic reaction, reactants __ heat from the solution | absorb |
Specific heat, or SH, is the __ | number of calories of heat needed to raise the temperature of 1 g of the substance by 1 degree C |
Regarding specific heat, what is the formula you must remember? | Q=ms X ΔT X SHs (the lower case s stands for solution, or for our purposes, water) |
The specific heat (HS) for water is __ | 1.0 cal/g degrees C |
To determine heat released or absorbed, you need to know __ | specific heat, total grams of solution, temperature change (did it increase or decrease?) |
If you see a word problem on the test, remember that __ are not needed to work the equation. | moles |
A capital C, or kilocalorie, is also used as a __ calorie. | nutritional |
Thermal kinetics is the study of __ | the rate, or speed, of chemical reactions. |
Kinetic information represents changes over __ | time |
Change in __ can be used to monitor the progress of a chemical reaction | color |
The __ of color change can help us calculate the rate of the chemical reaction | rate |
If sufficient energy is available, chemical bonds will break and atoms will recombine in a __ __ arrangement | lower energy |
An __ collision is one that produces product molecules | effective |
Activation energy is the __ | minimum amount of energy required to initiate a chemical reaction. |
An activated complex is __ | an extremely unstable, short-lived intermediate complex |
An activated complex cannot be __ from the reaction mixture | isolated |
Activation energy is the __ between the energy of the reactants and that of the activated complex. | difference |
What are the 6 factors that affect reaction rate? | 1) structure of reacting species 2) molecular shape and orientation 3) concentration of reactants 4) temp of reactants 5) physical state of reactants 6) presence of a catalyst |
In a reaction, oppositely charged species reactant more __ | rapidly |
Ions with the same charge __ | do not react |
The magnitude of the activation energy is related to __ | bond strength |
The rate of a reaction will generally increase as the concentration __ | increases |
A higher kinetic energy means a __ of these collisions will result in product formation | higher percentage |
Reactions are fastest in the __ state and slowest in the __ state. | liquid, gaseous |
A catalyst is a __ | substance that increases the reaction rate of a chemical reaction. |
The catalyst __ __ __ the final product of the reaction and undergoes no net change. | does not alter |
Equilibrium reactions are __ | incomplete chemical reactions. |
When a chemical reaction is complete, that means that all __ | reactants have been converted to products. |
Physical equilibria reactions are __ | reversible |
Examples of reversible reactions, or physical equilibrium reactions, include: | dissolved oxygen in lake water, stalactite formation, sugar dissolved in water |
A reversible reaction is a process that __ | can occur in both directions and uses the the double arrow symbol |
You have dynamic equilibrium when the rate __ | of the forward process in a reversible reaction is exactly balanced by the rate of the process in reverse |
T or F: if you add 100 g of sugar to 100 mL of water, nothing happens. | False, even though it may appear that way |
Equilibrium occurs when the rate __ | of reactant depletion is equal to the rate of product depletion |
LeChateleir's Principle says that __ | if a stress is placed on a system at equilibrium, the system will respond by altering the equilibrium composition to minimize the stress |
The term "stressed," as applied in LeChateleir's Principle, means that the equilibrium will be __ | disturbed |
Pressure affects equilibrium only if one or more of the substances in the reaction are __ | gases |
The relative number of gas moles on reactant and product side must __ to effect pressure | differ |
When pressure goes up, it shifts to the side with __ | less moles of gas |
A catalyst affects the rate of both the forward and reverse reaction to the __ extant | same |