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Chem 1B > Lab Exam 2 > Flashcards

Lab Exam 2 Flashcards

1
Q

The electrode which oxidation occurs is called

Where is it

A

Anode

On the left

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2
Q

The electrode which reduction occurs is called

Where is it

A

Cathode

On the right

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3
Q

Electrons flow from where to where

A

Anode to cathode

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4
Q

Anions flow from the _____ to the _______

A

Cathode to the anode

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5
Q

Cations flow from ______ to the ______

A

Anode to the cathode

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6
Q

In NaCl what is the anions and what is the cations

A

Anions is Cl-

Cations are Na+

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7
Q

For a cell reaction to occur spontaneously what must be what

A

E ^cell must be positive

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8
Q

Cell potential is represented by

What else is it known as

Units are

A

E^cell

standard emf

volts

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9
Q

Formula for E^cell

Important note…

A

E^cathode - E^anode

DO NOT CHANGE SIGNS FROM TABLE

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10
Q

The half reactiopn with the smallest reduction potential is…

A

The most easily reversed

Becomes an oxidation reaction

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11
Q

The more positive (+) the E^red from the table…

A

The more likely the reactant will be reduced

Therefore oxidise another species

THE STRONGER IT IS AS AN OXIDISING AGENT

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12
Q

The more negative (-) the E^red from the table…

A

THE STRONGER IT IS AS A REDUCING AGENT

  • = reducing
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13
Q

The formula for delta G using electrochem

A

Delta G = -nFE

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14
Q

What is the F constant

What is the R constant

A

96485 J/Vmol

8.314J/kmol

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15
Q

What is the other formula for Delta G using equilibrium constant

A

Delta G = -RTlnK

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16
Q

What is the formula for Ecell

A

Ecell = E^cell - 0.0592/n log(Q)

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17
Q

Which electrode is negative

A

Anode

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18
Q

What electrode is positive

A

Cathode

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19
Q

Lowest pH will contain…

A

The highest number of moles of H+ ions

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20
Q

What kind of acid will have the smallest Ka

A

The one with the highest pH

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21
Q

In exp 19 what does Al convert

A

Fe+3 into Fe+2

22
Q

In exp 19 Thiosulfate only reacts with

A

Fe+2

23
Q

Why if you skip the heating process Fe does it affect the concentration of Fe reported

A

Not all Fe is converted to Fe+2. Thiosulfate only reacts with Fe+2. Therefore the concentration of FE reported will be lower than the true value

24
Q

In exp 18, what is HCL required for

A

Turning all Hln into the red form

25
Q

In exp 18, what would happen if no HCL is added

A

Absorbance would be lower
Which makes the slope less steep = smaller value of slope

This is because HCL is what turns the Hln into the red mythl red

26
Q

What is the equation for absorbance

A

Slope X concentration

27
Q

What is the red form of mythl red

What is the yellow form of mythl red

A

Hln

In-

28
Q

Hln is what colour

A

RED

29
Q

Ln- is what colour

A

YELLOW

30
Q

What is the equilibrium set up of Hln

What is Keq of this

A

Hln H + ln

Keq = [H+][ln-]/[Hln]

31
Q

[Hln initial] is calculated by

A

[Hln]eq + [ln-]eq

32
Q

Why cant we just calculate H+ using 1:1 ratio

A

Because H is coming from another source in the water (H2O)

33
Q

In exp 21, what indicator is added

What does it react with

What colour does it produce

A

Starch

I2

Gives blue colour

34
Q

In exp 21, what is solution titrated with

What does it react with

What does it produce

A

Thiosulfate

Reacts with I2

Gives I-

35
Q

In exp 21, what two things do we mix

What solid does it form

A

KIO3 and CaCl2

Calcium iodate = Ca(IO3)2

36
Q

The iodate in exp 21 is converted all to

A

Iodine

37
Q

In exp 21, as you titrate the solution what colour change occurs

A

Goes from dark blue to light blue and then colourless

38
Q

How many moles of thiosulfate are required to titrate a mole of iodate

A

6 mol : 1 mol
6 thiosulfate
1 mol iodate

39
Q

in exp 21, going over the equilivence point caused the calculated value of Ksp to

A

Get bigger

40
Q

in Exp 21, not having any solid present in the tub when titrating caused the calculated value of Ksp to

A

Get smaller

41
Q

In exp 21, what was the ratio between thiosulfate and iodate

What was the ration between iodate and calcium

A

6: 1
2: 1

42
Q

An acid with a larger Ka will have a ______ pH

A

Lower pH

43
Q

An acid with a smaller Ka will have a ______ pH

A

Higher pH

44
Q

What is the units for keq

A

No units

45
Q

What is the R constant

What is the R constant for gases

A
  1. 314 J/Kmol

0. 08206

46
Q

What is the formula for Kp

A

Kp = Kc (RT)^ product mol - reactant mol

R = 0.08206

Stoichio coeff matters on R and T

47
Q

When Keq < 1

When Keq > 1

When Keq = 1

A

Reactant favored = moves to product

Product favored = moves to reactant

Equilibrium

48
Q

When Q < K

When Q > K

When Q = K

A

Reactant favored = moves to product

Product favored = moves to reactant

Equilibrium

49
Q

Endothermic reaction
What happens when temperature increases

What happens when temperature decreases

A

Shifts to Product
Increases Keq

Shifts to Reactants
Decreases Keq

50
Q

Exothermic reaction
What happens when temperature increases

What happens when temperature decreases

A

Shifts to Reactants
Decreases Keq

Shifts to Product
Increases Keq

51
Q

What happens when Pressure increases

What happens when Pressure decreases

A

Shifts towards whatever has LESS MOLES

Shifts towards whatever has MORE MOLES

52
Q

What happens when Volume increases

What happens when Volume decreases

A

Shifts towards whatever has MORE MOLES

Shifts towards whatever has LESS MOLES

Chem 1B (6 decks)

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