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chem1 Flashcards

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1
Q

A student introduces a particle of unknown identity between two oppositely-charged electrodes and notes that it accelerates toward one of the two electrodes. The particle could be any of the following, EXCEPT a(n):
A) anion. B) cation. C) neutron. D) proton.

A

C

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2
Q

A student desiring to eject an electron from a metal sample must choose between three metal elements available to him in the lab: sodium, magnesium, or potassium. To most easily accomplish his objective, the student should choose:
A) Na
B) K
C) Mg
D) Mg or K, because they exhibit equal metallic properties.

A

The periodic table trends indicate that elements to the left and down in the table will most easily give up a valence electron. Mg is one box to the right of Na, and K is one box below Na. Thus, B is the best answer, as Na is easier than Mg and K is easier than Na. The difference between adjacent family members is greater than the difference between adjacent periods, making B the best answer.

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3
Q

3) Two unique light sources are used to bombard a single metal sample with photons (φ = 349J). The first light source delivers photons with an energy of 700J at a rate of 1 x 105 photons per second. The second light source delivers 350 J photons at exactly twice that rate. If each light source is shone onto the surface of the metal for exactly one second, which of the following statements is true?
A) The second light source will eject twice as many electrons as the first.
B) The second light source will eject half as many electrons as the first.
C) Neither light source will eject electrons.
D) Electrons ejected by the second light source will have greater kinetic energy.

A

A

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4
Q

4) In a sealed container at room temperature, a student is observing the endothermic decomposition reaction wherein sulfuric acid is broken down into water, sulfur dioxide and diatomic oxygen. After the reaction has reached equilibrium, the student transfers the entire contents of the reaction vessel into an evacuated vessel with twice the volume. Which of the following is expected AFTER the transfer?
A) Less water will be produced.
B) The amount of sulfur dioxide gas present will increase.
C) Less sulfuric acid will decompose.
D) The reaction rate will increase due to the reduced pressure.

A

B

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5
Q

what does it mean to have metallic character?

A

big radius and low ionization energy

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6
Q

what is ionic bond characteristics?

A

-metal reacts with non-metal
-solid at RT
-high B.P
- great difference in electronegativity
- Conductive when liquid
-

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7
Q

What is true of covalent bond?

A
  • bond between two non metallic atoms which is characterized by the unequal sharing of pairs of electrons between atoms and other covalent bonds.
  • Low melting points
  • Low boiling points. …
  • Low enthalpies of fusion and vaporization
  • Soft or brittle solid forms. …
  • Poor electrical and thermal conductivity.
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8
Q

what happens if you react a group 1 or group 2 metal with water?

A

you get a violent exothermic reaction with H2 gas.

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9
Q

what makes a good insulator?

A
  • high energy of ionization
  • ## nonmetallic solids
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10
Q

what’s ranking for combustion?

A

add +1 for carbon

add +.5 for oxygen

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11
Q

What’s acetone structure?

A

C3O

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12
Q

what’s methane structure?

A

CH4

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13
Q

How do you go from moles to atoms?

A

6.022x10^23 (avogadro’s) / 1 mole

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14
Q

How do you go from moles to moles of another molecule?

A

1 mole of A / X mole of B –> based on reaction

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15
Q

How do you go from moles to grams?

A

moles= grams/mw

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16
Q

How do you go from mole to ions?

A

6.022x10^23 ions / 1 mole

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17
Q

How do you find moles from density?

A

Density = g/ L
so if you are given mL –> L x moles/g

if you are given density as g/cm^3 –> remember cm^3 = mL

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18
Q

Who do you find moles from pressure?

A

PV=nRT –> n = moles

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19
Q

How do you find rate law exponent?

A

1) two trials where only concentration of reactant 1 changes (and reactant 2 stays the same if there’s another reactant).
2) X= factor by which reactant changed and Z= factors by which rate changed –> X^y = Z –> find y= order of reactant.
3) do the same with the other reactant and find a trial where reactant 1 is constant.

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20
Q

what is an isotope?

A

atoms with same number of protons but different numbers of neutrons–> different atomic weight

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21
Q

What do metals form … but non metals form …

A

cations … anions

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22
Q

metals are found in groups?

A

group 1-13 (apart from metalloids) + Sn, Pb, FI, Bi, Uup, Lv

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23
Q

What are the metalloids?

A

Bull Shit Girls Are Smart Too Po!

B, Si, Ge, As, Sn, Te, Po

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24
Q

Which are smaller, cations or anions?

A

Cations are smaller because there’s a bigger + charge on the nucleus bring the few electrons closer.

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25
Q

What increases as you go to the RIGHT of the periodic table?

A

electronegativity, ionization, electron affinity

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26
Q

What increases as you go to the LEFT of the periodic table?

A

atomic radius

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27
Q

What increases as you go left and down the periodic table? (diagonally to the left)

A

metallic character

28
Q

Why do metals want to lose electrons?

A

large atoms with loosely held electrons –> enable them to form noble gas configuration.

29
Q

Why are large atoms (like metals and transition metals) better at stabilizing charges?

A

because they don’t form pi bonds and have d orbitals where they can house extra valence electrons.

30
Q

What is the quantum address of electrons set up as?

A

n (shell), l(momentum quantum #), ml(magnetic quantum #), ms (electron spin quantum #)

31
Q

What is Heisenberg’s uncertainty?

A

states that position and velocity of an object cannot both be measured exactly at the same time, even in theory.

32
Q

1) Beaker A contains 2.55 g of FeCl3 dissolved in 100 mL of water. Beaker B contains 10.20 g of FeCl3 dissolved in 400 mL of water. If the specific heat capacity of the solution in Beaker A is known to be 1.33 cal/g ̊C, what is the expected specific heat capacity of the solution in Beaker B?
A) 1.33 cal/g ̊C
B) 2.66 cal/g ̊C
C) 5.32 cal/g ̊C
D) Solutions do not have specific heat capacities.

A

A

33
Q

What is convection?

A

type of heat exchange that happens as fluid movement leads to cooler portions sinking and hotter portions rising (boiling water on a pan)

34
Q

what is heat radiation?

A

Electromagnetic waves emitted from hot body to surrounding. In the summer you want to wear lighter color because they absorb less heat and radiate less. Darker colors absorb more and radiate more heat.

35
Q

What is heat conduction?

A

High heat = high collision = high conduction because more particle hitting each other and moving along.

36
Q

What is the difference between heat and specific heat capacity?

A

heat capacity is energy absorbed/ unit change in a system . Equation is C=q/deltaT.

Specific heat is the energy absorbed for one individual substance only and is defined per unit mass. equation is c= q/mCAT or q=mcdelataT (mcat)

37
Q

What is the specific heat of water?

A

1 cal/gC or 4.18 J/gC

38
Q

What is the coffee cup calorimeter compared to Bomb calorimeter?

A

Coffee cup –> constant pressure –> q=mcAt (A= delta)

Bomb calorimeter –> q=CAT

39
Q

The hydration of ammonium nitrate is a highly exothermic dissolution reaction. Which of the following statements is NOT true of this process?
A) The reaction must be spontaneous because it is both exothermic and has a favorable entropy change.
B) The reaction could be spontaneous or non-spontaneous depending on the temperature at which the
reaction is run.
C) The products of the reaction have greater entropy than do the reactants.
D) The total bond energy of all the products exceeds the total bond energy of all the reactants.

A

B

40
Q

a reaction with a high energy of activation also has…

A
  • fast reaction rate
  • negative delta G
  • large Keq
41
Q

What changes Keq?

A

temperature

42
Q

what’s Keq?

A

products/reactants at equilibrium

43
Q

what are units of specific heat?

A

Joukes/g*C

44
Q

A substance that produces the greatest amount of heat per mole upon combustion has…?

A

highest delta H formation = high bond energy = least stable

45
Q

what is formula for heat capacity? what does it mean?

A

c= q/ delta T

Heat capacity is the amount of energy we can add before system increases by one temperature unit.

46
Q

what is formula for specific heat capacity?

A

q=mcat

47
Q

What is the coffee cup calorimeter? what are characteristics?

A

use q=mcat and has constant pressure + allows PV work because of the change in volume

48
Q

What is bomb calorimeter?

A

Does not allow for change in volume because volume stays constant –> q=CdeltaT

49
Q

On a pressure (y) vs volume graph, where is work?

A

area under graph

50
Q

what is the first law of thermodynamics?

A

energy can neither be created nor destroyed

51
Q

what is the second law of thermodynamics?

A

entropy in an isolated system can never decrease because heat cannot be changed completely into work in a cyclical process.

52
Q

what is the third law of thermodynamics?

A

pure crystalline substance at absolute zero have entropy of zero

53
Q

What is the zeroth law of thermodynamics?

A

if A is in thermal equilibrium with B and B is in thermal equilibrium with C then A and C ar win thermal equilibrium.

54
Q

What is temperature? what is the related kinetic energy formula for it?

A

Temperature is the average kinetic energy of molecules. Ke= 3/2 KbT –> shows direct relationship between T and Ke.

55
Q

How do you go from celsius to kelvins?

A

C +273 K

56
Q

What is enthalpy?

A

energy contained within chemical bonds –> delta H

if delta H is negative –> exothermic - spontaneous
if delta H is positive –> endothermic

57
Q

what is entropy?

A

measure of randomness/ disorder in a system.
has randomness increases (becomes more positive), energy is released and is available to dow work –> spontaneous process.

deltaS is positive = increased randomness(liquid to gas) and thus more energy = spontaneous.

deltaS is negative = decreases randomness (gas to liquid) and less energy = non spontaneous

58
Q

what increases as randomness/ entropy increases?

A

1) # of particles
2) volume
3) temperature
4) disorder
5) complexity (more complex molecules have more disorder than less complex molecules)

59
Q

What is the value of Gibbs free energy when the reaction is exothermic/ spontaneous?

A

Delta G negative

60
Q

what equation relates gibbs free energy to equilibrium constant?

A

DeltaG= -RTlnKeq

61
Q

what equation relate gibbs free energy to entropy and enthalpy?

A

DeltaG= deltaT- DeltaS

62
Q

what is the conceptual understanding of the henderson hasselbach equation?

A

pH = pKa - log([HA]/[A-]).
Namely, for every 1.0 unit difference between the pKa and the pH, the ratio of acid to base (or base to acid) will change by a factor of 10 (and following that trend, for every 2 units it would differ by a factor of 100, for every 3 units by a factor of 1,000 and so on).

63
Q

What is the relationship between acid, pKa, Ka ?

A

small pka= large Ka (over 1x10^0) = strong acid = 100% dissolution

64
Q

what is the pea of a substance A the has a KA of 1x10^2 and of substance B that has KA of 2x10^-5

A

a) pKa= -log(1x10^2) = -2

b) pKa= -log (2x10^5)= -(-5)= 5

65
Q

Which species has lowest KA?

a) HCLO4
b) HCLO3
c) HCLO2
d) HCLO

A

D- in a series of oxyacids, acid strength decreases as the number of oxygens decreases.

66
Q

What are polyatomic compounds?

A 
Hydroxide - OH-
Nitrate NO3 -1
Nitrite No2 -1
Perchlorate ClO4 -
Bicarbonate NaHCO3 -
Sulfate SO4 -2
Manganite MnO(OH)
Cyanide CN -1
Chlorate Clo3 -1
Chlorite ClO2 -1
Hypochlorite ClO -1
Carbonate CO3 -2 
Ammonium NH4 +1
Phosphate PO4 -3 
Permanganate Mn(VII)O4 -1
67
Q

What is order to balance reaction?

A

1) carbon
2) hydrogen
3) oxygen
4) remaining elements

chem (4 decks)

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