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Chemistry and Our Universe > Chapters 19-24 > Flashcards

Chapters 19-24 Flashcards

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1
Q

What is a spontaneous chemical reaction

A

One that will proceed to at least some extent without external assistance.

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2
Q

What are J. Willard Gibbs’s dates?

A

1839-1903

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3
Q

What is Gibbs free energy?

A

It gives us a way to combine enthalpy and entropy mathematically to determine whether the standard molar energy change for a process is positive or negative.

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4
Q

What does a positive free energy change mean for a reaction?

A

the reaction absorbs energy overall, so it is not going to take place without some outside assistance in the form of energy input. Non-spontaneous.

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5
Q

What does a negative free energy change mean for a reaction?

A

that the reaction releases energy to its surroundings and will happen all on its own, making it spontaneous.

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6
Q

What is the Gibbs free energy equation?

A

Delta G = Delta H - (T)*Delta S

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7
Q

What kind of process is occurring if the Gibbs free energy equation has a positive Delta H and a Negative Delta S?

A

It can never be spontaneous at or near standard conditions. Carbon turning into diamond, e.g.

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8
Q

What kind of process is occurring if the Gibbs free energy equation has a positive Delta H and a Positive Delta S?

A

we’ll have a reaction that is more spontaneous at higher temperatures. Melting of ice, e.g.

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9
Q

What kind of process is occurring if the Gibbs free energy equation has a negative Delta H and a Positive Delta S?

A

a reaction will always be spontaneous at or near

standard temperatures and pressures. Combustion of propane, e.g.

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10
Q

What kind of process is occurring if the Gibbs free energy equation has a negative Delta H and a negative Delta S?

A

we’d have to lower the temperature to make the reaction more likely to be spontaneous. In other words, it’s spontaneous at low temperatures. combustion of Hydrogen, e.g.

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11
Q

What are the 3 common phases of matter?

A

Solids, liquids and gases.

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12
Q

What are London dispersion forces?

A

temporary attractive forces that form when, just for an instant, the electron cloud of an atom or molecule becomes imbalanced.

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13
Q

How are London dispersion forces affected by the size of the atom?

A

as atoms and molecules become larger, and their electron clouds grow in size, interior electrons screen outer electrons from the nucleus, making them more susceptible to being pushed around from the outside of the atom.

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14
Q

What is a dipole‑dipole interaction?

A

For the same reason that transient dipoles align to form London forces, permanent dipoles can also align to form attractive relationships between and among molecules in a sample.

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15
Q

What are Hydrogen bonds?

A

intermittent but powerful attractions that take place between a very positively charged hydrogen and lone pair electrons from an atom carrying a very strong negative charge.

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16
Q

What are the three intermolecular forces?

A

London dispersion forces, dipole-dipole interaction and Hydrogen bonds.

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17
Q

Why is the density of ice only about 90% that of liquid water?

A

The lattice work of ice crystals formed by Hydrogen bonds, leaving more space.

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18
Q

What is a phase diagram?

A

a way to illustrate and demonstrate how and why a pure substance will change phases.

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19
Q

What is the triple point?

A

The unique set of conditions at which the solid, liquid and gaseous form of a substance can all exist in equilibrium.

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20
Q

What is the critical point?

A

The set of temperature and pressure conditions at which liquids and gases become essentially indistinguishable from one another, creating a new phase called supercritical fluid.

21
Q

What is sublimation?

A

going from a solid directly to gas.

22
Q

What is deposition?

A

Going from a gas directly to a sold.

23
Q

What is the heat of fusion?

A

The heat energy required to melt a given substance.

24
Q

What is the heat of vaporization?

A

The heat energy required to vaporize a given substance.

25
Q

What are Robert Boyle’s dates?

A

1627-1691

26
Q

What is Boyle’s law?

A

P=1/V. Or P1V1=P2V2. At a fixed temperature, the pressure of a gas sample is inversely proportional to its volume.

27
Q

What are Joseph Louis Gay-Lussac’s dates?

A

1778-1850.

28
Q

What is Gay-Lussac’s law?

A

P1/T1 = P2/T2. Pressure and temperature must be proportional when all other things are held constant.

29
Q

What are Jacques Charles’ dates?

A

1746-1823.

30
Q

What is Charles’ law?

A

T1/V1 = T2/V2. When pressure is held constant, a sample of gas will increase in volume proportionally to its absolute temperature.

31
Q

What are Amadeo Avogadro’s dates?

A

1776-1856.

32
Q

What is Avogadro’s law?

A

under constant conditions of pressure and temperature, an equal volume of gas contains an equal number of particles.

33
Q

When did Avogadro formulate his law?

A

1811.

34
Q

What is the combined gas law?

A

It combines Boyle’s, Gay-Lussac’s and Charles’ law into one equation: P1V1/T1 = P2V2/T2.

35
Q

What is the ideal gas law?

A

It adds Avogadro’s law to the combined gas law, yielding: PV = nRT.

36
Q

When do gases form?

A

When the atoms or molecules in a substance have sufficient kinetic energy to overcome the attractions that these particles naturally have for one another.

37
Q

What does rms velocity stand for?

A

Root-Mean-Square Velocity.

38
Q

How might you describe the energy of a single gas particle?

A

With the same type of equation that a physicist or engineer would for a large object: E = (1/2)mv2.

39
Q

On what two things does the velocity of a gas molecule depend?

A

Its temperature and molecular weight

40
Q

What’s the relationship between rms velocity of a gas sample and temperature?

A

The rms velocity of a gas sample is proportional to the square root of the absolute temperature.

41
Q

What is the relationship between the molar mass of a gas particle and its rms velocity?

A

A square root—just like with temperature—but this time it’s 1 over the square root of the molar mass.

42
Q

What is the formula for finding the actual rms velocity of a sample?

A

Vrms = SQRT(3RT/M)

43
Q

What are Thomas Graham’s dates?

A

1805-1869.

44
Q

What is Graham’s law of effusion?

A

The relative rates of effusion of 2 gases is proportional to the square root of the ratio of the molar masses of the 2 gases.

45
Q

What is viscosity?

A

Resistance to flow.

46
Q

What is the major reason that motor oil is more viscous than gasoline?

A

Massively more London dispersion forces in the larger molecules in motor oil.

47
Q

What is volatility?

A

The tendency and speed with which a substance vaporizes.

48
Q

What is vapor pressure?

A

The pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system.

49
Q

What is miscibility?

A

a description of how well one liquid dissolves into another liquid.

Chemistry and Our Universe (6 decks)

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