Lab Final Flashcards Preview

Chemistry 101 > Lab Final > Flashcards

Flashcards in Lab Final Deck (111):
1

precision vs accuracy (A)

precision- how well repeated measurements agree with each other
accuracy- how well the measurement agrees with the accepted value

2

error vs relative error (A)

error- sum of errors
relative error (percent)- sum of errors/found value * 100

3

sig figs when adding/subtracting vs when multiplying/dividing (A)

add/sub- smallest number of figures to the RIGHT of the decimal (ie 15.16 + 0.168- answer is 15.33)
mult/div- smallest number of figures OVERALL is used

4

if log(100) = 2 is equivalent to 10^2 = 100, solve:
log(1/T) = A for T
(A/J)

log(1/T) = A
10^A = 1/T
T = 1/10^A
*log(100) is equivalent to log10(100)*

5

what type of spectrum does sunlight vs light emitted by gases give? (A)

sun- continuous
gas- discontinuous

6

3 common applications of light emissions by elements (A)

1. flame test (ID's presence of elements)
2. fireworks
3. fluorescent lights (mercury tubes)

7

symbol and units for frequency (A)

v, cycles/second, Hz

8

what is Z the symbol for? (A)

nuclear charge (aka atomic number)

9

in what order do wavelengths of the visible spectrum increase? (A)

violet < blue < green < yellow < orange < red

10

formula for c (A)

λv = c

11

formula for Ephoton (A)

Ephoton = hv = hc/λ]

12

Consider green, yellow and red lights. Arrange these in order from highest to lowest energy and explain why. (A)

Highest- green, yellow, red
- energy and wavelength have an inverse relationship, meaning the shorter the wavelength, the higher the energy

13

For the H atom, the longest wavelength of the spectral lines in Balmer series (all transitions to n=2) corresponds to the transition from n=x to n=2. What is the value of x? Explain. (A)

X = 3
- the e- is only dropping one level from n=3 to n=2, therefore releasing a low amount of energy. Since energy and wavelength have an inverse relationship, the e- has the longest wavelength in the Balmer series.

14

For the H atom (Balmer series, all transitions to n=2), the shortest wavelength of the spectral series corresponds to the transition between n=x to n=2. What is x? Explain. (A)

X = infinity
- the higher the value of x, the more energy is released, therefore the shorter the wavelength (inverse relationship)

15

Incandescent (bulb) (A)

Emits light as a result of being heated

16

Incandescent bulbs show which type of spectrum? (A)

Continuous

17

Fluorescent lights have which type of spectrum? (A)

Discontinuous

18

When using a spectrometer, light is split into a range of wavelengths and passed through a sample. Some of this light might be ____. (also what is this function called) (A)

absorbed (function A- absorption)

19

2 possible reasons for an object to show a particular colour (A)

1. reflection of the object's colour
2. absorption of the complementary colour

20

____ is the most abundant metal in the Earth's crust and third most abundant metal behind oxygen and silicon (B)

aluminum

21

BONUS CARD- the main ore of Al is ____ (B)

bauxite

22

AL(OH)3 is/is not amphoteric, meaning... (B)

is, it can react either with acid or base

23

t/f- P2O5 is abundant in fertilizers (B)

false- the usual phosphorus compound is (NH4)H2PO4

24

give the empirical, molecular and structural formulae for hydrogen peroxide, also describe what info each formula provides (B)

empirical- HO (shows relative number of atoms (lowest whole # of moles))
molecular- H2O2 (shows actual amount of atoms of each element in molecule)
structural- H-O-O-H (shows relative placement and connections of atoms)

25

BONUS CARD- molecular formula for acetic acid (B)

CH3COOH(aq)

26

when calculating molar mass of a hydrate, do we incorporate the ·xH2O? (B)

yes

27

hydrate vs anhydrate (B)

hydrate- has ·xH2O at the end
anhydrate- substance that remains after the water is removed from a hydrate

28

t/f- copper readily reacts with sulfuric and hydrochloric acids, provided they are strong enough (C)

false- does not react

29

copper reacts with ____ acid (molecular formula), which is a strong ____ ____, and forms the water soluble... (C)

copper reacts with NITRIC acid (HNO3), which is a strong OXIDIZING AGENT, and forms the water soluble copper (II) nitrate

30

What are the two common oxidation states of copper? Which one is more stable? (C)

copper (I) and copper (II)
copper (II) [+2 oxidation state] is more stable

31

Copper (II) nitrate can be formed by adding nitric acid to copper metal. One by product of this reaction is water. The other is the colourless gas ... (also describe what would happen if this reaction was in the presence of O2) (C)

nitrogen monoxide (NO)
- if exposed to air, the NO immediately reacts to form the poisonous reddish brown nitrogen dioxide (NO2) gas

32

copper (II) carbonate is ____ and it ____ (C)

insoluble, precipitates

33

filtrate (C)

liquid that passes through filter into filtrate flask

34

BONUS CARD- the filtrate for copper (II) carbonate should be what colour? Why? (C)

- clear because copper (II) carbonate is insoluble in water

35

traditional copper cycle experiment process when transforming copper into copper (II) sulfate [4 steps- chemical equation] (C)

Cu → Cu(NO3)2 → CuCO3 → CuSO4

36

Addition of small amounts of aqueous ammonia to copper sulfate sol'n leads to the formation of ___ ___ Cu(OH)2. However, if large amounts are added, the ammonia bonds to __+, producing the ___ ___ ion Cu(NH3)4 2+ (C)

light blue
Cu2+
dark blue

37

What VSEPR arrangement does tetraamminecopper (II) sulfate monohydrate (Cu(NH3)4(SO4)·H2O) have? What 2 things are added to make it? (C)

square pyramidal
NH3 + copper (II) sulfate

38

tetraamminecopper (II) sulfate monohydrate (Cu(NH3)4(SO4)·H2O) is very soluble in ____, but not in ____ (C)

soluble- water
insoluble- ethyl alcohol

39

What is formed by the addition of NaOH to copper (II) sulfate (has light blue colour)? What happens when excess NaOH is added? (C)

- Cu(OH)2(s)
- more precipitate forms

40

molecular formula for copper (II) sulfate (C)

CuSO4

41

Give the oxidation-redution reaction in the lab manual for when Zn(s) is added to CuSO4. For the experiment, what is the effect of this? (C)

Zn(s) + Cu2+ → Zn2+ + Cu(S)
- precipitates out the metallic copper (which is the goal)

42

Does zinc prefer to react with H2SO4 (sulfuric acid) or Cu2+? Describe what this means (C)

H2SO4
- only when H2SO4 is consumed will zinc start to replace copper

43

water of hydration (water of crystallization) (D)

water that is chemically combined with a substance to form a hydrate

44

hydrates that spontaneously lose water to the atmosphere are termed ____ (D)

efflorescent

45

why do efflorescent hydrates lose water to the atmosphere? (D)

vapor pressure of water exerted by efflorescent solids is greater than vapour pressure of water in atmosphere

46

compounds that spontaneously absorb water from the atmosphere are termed ____(D)

hygroscopic

47

efflorescent/hygroscopic compounds are used to dry liquids/gases, and are sometimes called ____ (D)

hygroscopic, desiccants

48

why do hygroscopic compounds absorb water from the atmosphere? (D)

vapor pressure of water exerted by hygroscopic compounds is less than vapour pressure of water in atmosphere

49

compounds that absorb water from the atmosphere that they dissolve in their own water of hydration are called...(D)

deliquescent

50

how do we remove the water of hydration/crystallization fro a hydrate? (D)

heat at temperature where vapour pressure of water exerted by hydrate > partial pressure of water in atmosphere above the hydrate

51

a hydrate where all water of hydration has been driven off is in its ____ form (D)

anhydrous

52

as a hydrate is heated, the compound may undergo any of these 3 changes: (D)

1. colour change
2. form of crystal may change (dry, powdery solid usually results)
3. may dissolve in own water of hydration (if continue to heat, this water will evaporate, leaving anhydrous solid behind)

53

formula for mass % of water in a hydrate (D)

mass water/original mass of hydrate * 100

54

what is the formula for ratio when calculating formula of a hydrate? (D)

larger # moles/ smaller # moles
or
mol H2O/ mol hydrate

55

describe what happened when (initially blue) CuSO4 hydrate was heated and when water was re-added (D)

heating- turned white
water- when added back, returned blue colour to Cu2+ ions

56

describe what happened when sucrose was heated and when water was re-added (D)

heating- decomposed into carbon and H2O (CHEMICAL CHANGE, not just physical)
water- ^ therefore, re-adding water had no impact

57

ascorbic acid is another name for...(give formula as well) (F)

vitamin C, C6H8O6

58

limiting reactant (F)

substance with less moles present ("limits" the rxn)

59

stoichiometric point (graph) represents the point at which reactants are in stoichiometric proportion/factor, meaning...(F)

they are in the mole ratio such that neither reactant remains after the reaction

60

experimentally, what is a common way to determine the stoichiometric point? (F)

titration (indicated by colour change)

61

difference between endpoint and equivalence point in a titration (F)

endpoint- titration is finished, change of colour occurs
equivalence- reactants are stoichiometrically equal

62

How do you calculate the moles of acidic p+ due to an unknown acid "H2B" (assuming you have the total moles of acidic p+ and the number caused by vitamin C)? How do you calculate the moles of H2B (say each equivalent of H2B reacts with 2 equivalents of NaOH)? (F)

mol acidic p+ - mol of acidic p+ due to vitamin C
moles due to H2B/ # equivalents

63

intensive vs extensive property (G)

intensive- doesn't depend on amount of matter
extensive- depends on amount of matter

64

heat capacity C (G)

amount of heat needed to change temperature of an object per degree

65

specific heat capacity c vs molar heat capacity Cm (G)

specific- amount of heat needed to change 1kg of mass by 1K
molar- amount of heat needed to change 1 mole by 1K

66

t/f- systems contain heat (G)

false- contain internal energy (heat or work is the means by which energy is transferred between bodies)

67

specific heat capacity C formula (G)

C = q/Tf-Ti OR ΔH/Tf-Ti
where q = heat (energy), q = ΔH for this lab

68

how do we calculate C from c or Cm? (G)

C = c * mass substance
C = Cm * mass substance

69

enthalpy H (G)

total "heat" (internal energy) of a system

70

for this lab, ΔH of a system =...(G)

0

71

Cblock formula (G)

-(Cwater * (Tf-Ti)water)/(Tf-Ti)block

72

cblock formula (G)

Cblock/mass of block

73

ΔH block = -ΔH...(2) (G)

water or 2-PrOH

74

ΔH fusion + ΔH ice water =...(G)

-ΔH water

75

what is a calorimeter used for? (G)

measuring enthalpy changes of rxns

76

how do we calculate the factor by which 2 heat capacities vary? (G)

higher C/lower C

77

BONUS CARD- atomic radii AND metallic character increase/decrease from left to right and increase/decrease from top to bottom (I)

decrease left right
increase top to bottom

78

BONUS CARD- ionic vs covalent bonds (I)

ionic- transfer of e-
covalent- sharing e-

79

what is the measure of an atom's ability to attract e- in a molecule called? (I)

electronegativity (X)

80

how do we calculate ΔX (electronegativity) of a bond? (I)

larger X - smaller X

81

BONUS CARD- London forces are due to instantaneous...(I)

dipoles that occur in a molecule

82

what are the typical IMFs in covalent compounds? (I)

van der Waals forces

83

hydrogen bonding is a strong form of ... bonding, and occurs between H in a bond with... (I)

dipole-dipole
electronegative atom

84

what are the acid-base statuses of the oxides of the elements (ionic vs covalent compounds) [2 names each] (I)

ionic oxides- basic, "base anhydride"
covalent oxides- acidic, "acid anhydride"

85

ionic oxides ALWAYS involve..., what is the use of this? (I)

metals (used to distinguish between basic metal oxides and acidic non-metallic oxides)

86

do covalent or ionic oxides dissociate in water? (I)

ionic

87

for a weak acid HA, the [H3O+] concentration at equilibrium increases/decreases as [HA]initial (initial molarity) decreases, but the % dissociation is smaller/greater for dilute solutions of HA than for more concentrated solutions (I)

decreases, greater

88

2 reasons for greater strength of hydrogen bonding (I)

1. greater bond polarity
2. small size of H atoms

89

requirements for electronegativity in a bond for ionic, polar covalent and covalent bonds (I)

ionic- 2+
polar covalent- <2
covalent- 0

90

Arrhenius and BL definition of a base (I)

Arrhenius- substance with OH-
BL- any substance that accepts a p+

91

is NaCl more soluble in water or hexane? (I)

water

92

are halogens more soluble in water r hexane? (I)

hexane

93

dissociation vs dissolution (I)

dissolution- molecule unchanged
dissociation- molecule changed

94

2 factors affecting the strength of acid as R = (H3-xClxC)changes from CH3 to CCl3 (I)

1. ability of Cl (most electronegative element present) to draw e- away from O-H bonds
2. how stable the formed anion is

95

spectroscopy- definition and 2 things it can provide insight on (J)

study of interaction of EMR with a chemical
1. what atoms are present
2. how they're connected

96

qualitative vs quantitative spectroscopy (J)

qualitative- determines what is in a sample by looking at line shapes, intensities, wavelengths
quantitative- determines how much of a given component is present in a mixture

97

spectra (J)

graph of the amount of radiation absorbed/not absorbed* vs some function of light energy
*not absorbed = transmitted

98

formula for amount of radiation transmitted (transmittance) (J)

T = I/I0
where I0 is intensity of incident radiation and I is intensity after passage through the sample

99

formula for absorption (J)

A = log(1/T)

100

UV-vis (spectroscopy type) (J)

- used qualitatively and quantitatively
- qualitative rarely used alone (spectra can be similar for different molecules)
- good when you know what molecules are present and just want to know how many there are

101

IR- infrared (spectroscopy type) (J)

- used qualitatively
- gives info re molecule structure
- causes molecule to vibrate, specific functional groups absorb radiation at characteristic wavelengths (helps ID parts of, and therefore, the molecule)

102

NMR- nuclear magnetic resonance (spectroscopy type) (J)

- uses radio frequency, light
- used qualitatively (deduces molecule structure)
- especially useful because is element specific (each element as normal range over which it will be resonant, different frequencies within this range correspond to certain environments)
- also used for medical imaging

103

multiplicity (NMR) (J)

number of peaks in a group

104

the area under the peaks in a group is related to... (J)

the number of p+ connected to the same atom

105

transmission increases/decreases with concentration (J)

decreases

106

absorption increases/decreases with concentration (J)

increases

107

Beer-Lambert law (J)

A = εbc
where ε= molar absorptivity (L/cm*mol)
b = cuvette length
c = concentration

108

1 ppb = (J)

0.001 ppm

109

1 ppm = how many grams/kg? (J)

10^-6

110

3 compound types with -C=O functional group, but not hydroxyl OH group (J)

1. aldehyde
2. ketone
3. ester

111

mole ratio for:
1 mol...
P2O5 to MgNH4...H2O
KIO3 to vitamin C (C6H8C)
NaOH to vitamin C (C6H8C)

1 mol P2O5 : 2 mol MgNH4...
1 mol KIO3 : 3 mol vitamin C
1 mol NaOH : 1 mol vitmanin C