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Chem110 Test 7
Review for Chem110 Test 7 Deltech-Owens Campus
| 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 |
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IsaacJ
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