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DAT Prep > General Chemistry > Flashcards

General Chemistry Flashcards

0
Q

What properties determine boiling point?

A
  • -The strength and amount of intermolecular forces.
  • -A molecule with the strongest intermolecular forces will have the highest boiling point
  • -If two molecules have the same type of intermolecular forces, the molecule with the greater molecular weight will have the higher boiling point
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1
Q

What conditions must be met in order for a molecule to participate in hydrogen bonding?

A

A very electronegative atom (F, O, N) must be DIRECTLY BONDED to hydrogen

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2
Q

Which intermolecular force is the strongest?

A

Hydrogen bonding

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3
Q

What is the trend for determining atomic radius question

A
  • -Atomic radius is inversely proportional to effectiveness nuclear charge
  • -Atomic radius increases from right to left and increases down a group
  • -If two elements, or ions, have the same number of electrons, the element with the fewer number of protons will have a larger atomic radius
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4
Q

What are the different types of intermolecular forces?

A

??

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5
Q

How do you calculate the heat of combustion?

A

Heat of Combustion = Heat of products - Heat of Reactants

Remember that the heat of formation for the most stable form of an element is 0 (ex. O2 heat of formation is 0)

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6
Q

How do you calculate formal charge?

A

F.C. = val. electrons - (# of sticks + # of dots)

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7
Q

How do you calculate the overall rate of a reaction mechanism?

A

When given a table of values, observe how the concentration of one reactant and the reaction rate changes as you hold another reactant constant

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8
Q

How do you calculate the rate law for an elementary step in a larger reaction mechanism?

A

Elementary reaction steps have a rate that is directly proportional to the concentration of their reactants raised to their stoichiometric coefficients
— (note that overall reactions do not necessarily follow this rule, because they are composed of many elementary steps)

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9
Q

How do you calculate how much heat something absorbs?

A

q = mc(delta T)

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10
Q

What is the formula to calculate Gibbs free energy?

A

Delta G = deltaH - TdeltaS

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11
Q

What is the formula to calculate standard Gibbs free energy?

A

Delta G = -RTln(Keq)

R=8.31 (this has Joules in it)

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12
Q

What is the solubility rule for salts alkali metals?

A

All salts of alkali metals are water-soluble

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13
Q

What is the solubility rule for nitrates?

A

All nitrates are water-soluble

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14
Q

What is the solubility rule for the salts of the ammonium ion (NH4)?

A

All salts of the ammonium ion are water-soluble

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15
Q

What is true about the solubility of carbonates, phosphates, sulfides, and sulfites?

A

They are insoluble except when they’re complexed with alkaline metals or ammonium ( I.e. When they are with the elements that are always soluble in water, rule 1)

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16
Q

What is true about the solubility of every halogen salt other than fluorine (chlorides, bromides, and iodides)?

A

They are always soluble in water except when they contain silver, mercury, or lead ions

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17
Q

All metal oxides are insoluble except when they are combined with which elements?

A

Calcium, strontium, barium, and alkali metals

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18
Q

All hydroxides are insoluble except when they’re combined with which ions?

A

Calcium, strontium, barium, and alkali metals

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19
Q

Also sulfates are soluble with what exceptions?

A

Sulfates combined with calcium, strontium, and barium are insoluble

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20
Q

What is a trick question regarding how to calculate molarity of a solution?

A

If you are given the volume of the solvent, but not the ending volume of the solution. Remember, molarity is moles per liter of solution, NOT moles per liter of solvent

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21
Q

What is molality?

A

The number of moles of solute per kilogram of solvent

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22
Q

What is normality?

A

Molarity multiplied by n, where n represents the moles of reactive species produced per mole of solute

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23
Q

What is the formula to calculate vapor pressure depression?

A

Psolution = Xsolvent * Psolvent

where X is equal to the mole fraction of the solvent

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24
Q

How do you calculate boiling point elevation?

A

deltaT = Kb * m

Where m is molality, and Kb is the boiling point constant specific for each solvent

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25
Q

How do you calculate freezing point depression?

A

deltaT = Kf * m

Note: this is the same formula as for boiling point elevation except we are now using Kf

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26
Q

How do you calculate osmotic pressure?

A

Osmotic Pressure = MRT

where M=molarity, R=0.0821, and T=temperature

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27
Q

When calculating boiling point elevation problems, what is important to keep in mind regarding what is being added to water?

A

Remember that many molecules will dissociate in water, so when you calculate the molality, keep in mind that you could have several ions for each molecule you put into water

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28
Q

In thermal expansion problems how do you calculate the change in length of an object?

A

deltaL = alphaLdeltaT

Where alpha equals the coefficient of linear expansion, L equals the original length of the object, and T is the temperature

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29
Q

How do you calculate and objects change in volume due to some temperature change?

A

deltaV = BVdeltaT

where B is the coefficient of volumetric expansion (also equal to 3*alpha) and V equals the original volume

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30
Q

What is the formula needed to calculate the heat of fusion or heat of vaporization?

A

Q=m*L

where L is the heat of transformation

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31
Q

How would you calculate the amount of energy required to take a block of ice at -10 deg C to 10 deg C?

A

Incorporate Q=mcdeltaT

and Q=m*L

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32
Q

When working with the ideal gas law what is the gas constant you should memorize?

A

R=0.0821 Latm/( Kmol)

33
Q

What is the formula for calculating the change in internal energy for a monatomic gas?

A

deltaU = 1.5nR*deltaT

34
Q

What is the sign convention for work done BY a gas?

A

Positive

35
Q

What is the sign convention for work done ON a gas?

A

Negative

36
Q

How do you calculate the change in internal energy of a gas (first law of thermodynamics)?

A

deltaU = Q-W

37
Q

Given a pressure-volume (PV) plot, how can you calculate the work?

A

The work done by sample of gas during any thermodynamic process is equal to the area underneath its PV curve

38
Q

How do you calculate the total amount of work done by a system for a cyclic process using a PV curve?

A

The total area enclosed within the plot is equal to the total work done by the gas

Remember, that because the process is cyclic the change in internal energy of the gas is zero

39
Q

What is the change in internal energy equal to in an isothermal process?

A

Zero. Q=W

40
Q

What is the difference between an adiabatic process and an isothermal process?

A

Heat can be gained or lost in an isothermal process in order to keep the temperature constant. No heat is gained or lost in an adiabatic process (I.e. Q=0)

41
Q

What is the second law of thermodynamics?

A

The entropy of a system and its surrounding environment together will either increase or remain unchanged for anything thermodynamic process

42
Q

What is the formula to calculate the energy of an electron?

A

E=h*f

Where h=planks constant and f=frequency

43
Q

How do you calculate the energies of electrons at specific energy states?

A

En= -13.6eV / (n^2)

Where En equals the energy of the electron at a given principal quantum number

44
Q

What initially triggers the emission of a photon for a fluorescent substance?

A

UV light is absorbed causing an electron to be excited to a higher energy level. While returning to its ground state it emits a photon

45
Q

When should you apply E=mc^2 on Test Day?

A

When calculating binding energy and mass defect of a nucleus

46
Q

What is Binding Energy?

A

The energy which holds the nucleus together

47
Q

How do you oh calculate mass defect?

A

The difference between the sum of the masses of the nucleons (protons + neutrons) and the mass of the nucleus

48
Q

How are mass defect and Binding Energy related mathematically?

A

BE=delta(m)*c^2

E=mc^2

49
Q

What is the conversion between amu to kg?

A

1 amu= 1.66*10^-27 kg

50
Q

What is planks constant equal to?

A

h=4.1510^-15 eVs

51
Q

What is the trend for whether an ionic radius or atomic radius is larger?

A

Cations ionic radius is smaller than the atomic radius, whereas anions ionic radius is larger.

52
Q

What is the volume that a gas will occupy at STP?

A

22.4 liters

Standard temperature and pressure are 1 atm, and 273 K, with a gas constant of 0.0821

53
Q

What is Dalton’s law of partial pressures?

A

It states that the pressure exerted by each gas in the mixture will be equal to the pressure that gas would exert if it were the only one in the container

54
Q

The three assumptions of the Kinetic Theory of Gases?

A
  • -An ideal gas is composed of particles of negligible volume and in constant the random motion
  • -No interactions among the particles and any collisions are completely elastic
  • -The average kinetic energy of the particles is proportional to the absolute temperature
55
Q

Where are the active metals found on the periodic table?

A

On the far left, particularly those in the lower left-hand corner

56
Q

Where are the active nonmetals found on the periodic table?

A

In the upper right hand corner, but not in the last column

57
Q

What is the shortcut used to calculate the pH of a substance?

A

-log(m*10^-n)= (n-1).(10-m)

58
Q

What is ionization energy?

A

The amount of energy required to remove an electron completely from a gaseous atom or ion

59
Q

What is the formula for calculating EMF?

A

Ered+Eox

For galvanic cells the standard emf is positive, while for electrolytic cells it is negative

60
Q

How do you know if a solution is saturated?

A

Ksp=ion product

61
Q

What does it mean when: ion product < Ksp ?

A

No precipitate will form and more of the solute can be added to the solvent

62
Q

What happens when the ion product is greater than Ksp?

A

Precipitate will form, and no more salt can be dissolved

63
Q

What is the common ion effect?

A

The solubility of sparingly soluble salts goes down in the presence of a common ion (for example the solubility of AgCl will decrease if NaCl is added to the solution)

64
Q

What is the formula for percent error?

A

100*(theoretical yield-actual yield)/theoretical yield

65
Q

What is beta- decay?

A

When a neutron becomes a proton and an electron

67
Q

What happens in beta+ decay?

A

A proton becomes a neutron and a positron

68
Q

Every slightly soluble salt of the general formula A_B3 (B sub 3) will have a general Ksp of:

A

Ksp=27*x^4

69
Q

Every slightly soluble salt of the general formula A_B2 (B sub 3) will have a general Ksp of:

A

Ksp=4*x^3

70
Q

Does the solubility of a gas in a liquid increase or decrease with a decrease in temperature, and why?

A

It will increase
Dissolving a gas in solution releases heat. If you reduce the heat the equilibrium will shift to dissolve more gas in the solution and produce more heat

71
Q

What are the qualities of a paramagnetic substance?

A
  • -Contains one or more unpaired electrons
  • -Magnetic moments are randomly arranged
  • -When placed in a magnetic field the magnetic moments align
  • -These are attracted into a magnetic field
72
Q

What are the qualities of a ferromagnetic substance?

A
  • -These substances can be made into permanent magnets

- -Also contains unpaired electrons, which align permanently after being placed in a magnetic field

73
Q

What is the best way to rank ionization energies?

A

Ionization energy increases up and to the right, with Helium having the highest ionization energy.
Simply count the number of electrons (which equals the number of protons for a neutral atom) to find which element you have

74
Q

How can you simplify a “find the rate” problem?

A

Write each number in the column as a small, whole number multiple of the smallest number in the column

75
Q

How do you solve a rate problem when there isn’t two values held constant in a column?

A

You should be able to solve the rate for one of the reactants. See how it changes from 1-2 and then from 2-3. If, for example, B is double and the rate quadruples from 1-2, and the same thing happens from 2-3, then the rate is zero order with respect to column A and second order with respect to B

76
Q

You have 8 different types of gasses in a closed container of 22.4 L. At STP how many total moles of gas do you have?

A

1 mole
Remember, at STP with a volume of 22.4 L you always have 1 mole of gas (no matter how many different types of gas are filling the container, that is the total amount by definition)

77
Q

What are the two types of double-displacement reactions?

A

Precipitation and Neutralization

78
Q

How can you tell the difference between an intermediate and a catalyst in a reaction?

A

An intermediate will be created as part of the reaction process and then will be used up. A catalyst will exist at the beginning and end of the reaction unchanged.

79
Q

When is the gas constant 8.314 used?

A

When your pressure is in kilopascals.

80
Q

When do you use 0.082 as the gas constant?

A

When your pressure is in atmospheres

81
Q

How do you calculate the bond length between two molecules when you’re given the bond lengths of those molecules in the pure form (I.e. Cl-Cl length is 199 pm and C-C length is 154 pm, what is the Cl-C length)?

A

Simply take the average of the two lengths, which in this case would be 176.5 pm

82
Q

What must you be careful of calculating osmotic pressure?

A

Remember osmotic pressure will increase if you have

DAT Prep (14 decks)

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