ANAL CHEM 4 Flashcards by ROLLIE ESTEVES

Which of the following is the formula for pH calculation?

log10[H+].
-log10[H+].
log2[H+].
-log2[H+].

-log10[H+].

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Pure water is known to be which of the following?

Weak electrolyte
Strong electrolyte
Neither weak nor strong
Not an electrolyte

Weak electrolyte

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Which of the following is the value of hydrogen ion concentration of pure water?

1×107 moles/litre
1×105 moles/litre
1×106 moles/litre
1×108 moles/litre

1×107 moles/litre

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Which of the following is the value of hydroxyl ion concentration of pure water?

1×107 moles/litre
1×105 moles/litre
1×106 moles/litre
1×108 moles/litre

1×107 moles/litre

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Which of the following is the relation between hydrogen and hydroxyl ion concentration of pure water?

Value of hydrogen ion concentration is greater
Value of hydroxyl ion concentration is greater
They are both always the same
The concentrations keep changing

They are both always the same

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The Nernst equation is given by which of the following statements?

E=Eo + 2.303 RT/F log CH
E=Eo – 2.303 RT/F log CH
E=Eo + 2.303 RT×F log CH
E=Eo – 2.303 RT×F log CH

E=Eo + 2.303 RT/F log CH

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Which of the following is the relation between concentration of hydrogen and hydroxyl ions in an acidic solution?

Value of hydrogen ion concentration is greater
Value of hydroxyl ion concentration is greater
They are both always the same
The concentrations keep changing

Value of hydrogen ion concentration is greater

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Which of the following is the relation between concentration of hydrogen and hydroxyl ions in a basic solution?

Value of hydrogen ion concentration is greater
Value of hydroxyl ion concentration is greater
They are both always the same
The concentrations keep changing

Value of hydroxyl ion concentration is greater

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The measurement of hydrogen ion concentration can be made by measuring the potential developed in an electrochemical cell.

True
False

True

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Slope factor is independent of temperature.

True
False

False

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Which of the following is not the characteristic of a reference electrode?

It must have a known output potential
It must have a constant output potential
Its output potential is dependent on the composition of the solution
It is employed in conjunction with the indicator or working electrode

Its output potential is dependent on the composition of the solution

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Why is Standard hydrogen electrode called as the primary reference electrode?

It has a known output potential
It has a constant output potential
Its output potential is independent of the composition of the solution
Its output potential is zero volts

Its output potential is zero volts

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Which of the following is the simple and most convenient hydrogen electrode?

Pascal Hydrogen electrode
Bourne Hydrogen electrode
Hilderbant Hydrogen electrode
West Hydrogen electrode

Hilderbant Hydrogen electrode

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Which of the following is not the disadvantage of hydrogen electrode?

Platinum can be easily poisoned

Presence of oxidising agents alters the potential

It gives salt error

H2 gas at 1 atmospheric pressure is difficult to set up and transport

It gives salt error

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In Hydrogen electrode, the electrode is placed in a solution of ____ M HCl. Fill in the blank.

0.5
1
2
3

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Hydrogen electrode which is the reference electrode can be used as which of the following?

Anode only
Cathode only
Anode or Cathode
Salt bridge

Anode or Cathode

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If hydrogen electrode acts as cathode, hydrogen is reduced.

True
False

True

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The composition of glass membrane in glass electrode cannot have which of the following?

Sodium silicate
Calcium silicate
Lithium silicate
Barium silicate

Barium silicate

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Which of the following is the purpose of added membranes in the glass membrane of the glass electrode?

They act as tightners
They act as filters
They act as conditioners
They act as collectors

They act as tightners

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Which of the following cannot form the inner reference electrode in glass electrodes?

Silver electrode
Copper electrode
Calomel electrode
Silver chloride electrode

Copper electrode

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The pH response of glass electrode is limited entirely to the area of the special glass membrane bulb.

True
False

True

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Which of the following is not the advantage of glass electrodes?

It gives accurate results for high as well as low pH values

It is simple to operate

It has no salt error

Modern electrodes can withstand severe treatment

It gives accurate results for high as well as low pH values

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Which of the following cannot be used as secondary reference electrode?

Calomel electrode
Silver-silver chloride electrode
Mercury-mercury sulphate electrode
Glass electrode

Glass electrode

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Which of the following is known as calomel?

Silver chloride
Mercury chloride
Potassium chloride
Mercury sulphate

Mercury chloride

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The calomel electrodes are classified based on which of the following? Materials used in the electrode Amount of mercury present Concentration of Kcl Purity of mercury

Concentration of Kcl

Which of the following calomel electrodes are used for accurate work? Saturated calomel electrode Electrode with 0.1M Kcl Electrode with 1M Kcl Electrode with 2M Kcl

Electrode with 0.1M Kcl

Calomel electrode can behave as which of the following components? Anode only Cathode only Anode or cathode Salt bridge

Anode or cathode

When the calomel electrode acts as the cathode which of the following does not occur? Mercury ions are discharged at the electrode More calomel passes into the solution There is a decrease in the concentration of chloride ions There is an increase in the concentration of chloride ions

There is an increase in the concentration of chloride ions

Which of the following is not the characteristics of calomel electrode? The potential of electrode is not temperature dependent Preparation of electrode is easy Value of potential or emf is higher for lower concentration of Kcl Value of potential decreases with increasing concentration of Kcl

The potential of electrode is not temperature dependent

Which of the following is not the characteristics of silver/silver chloride electrode? These electrodes have good electrical and chemical stability It can be used in temperatures greater than 600oC It can be used in places or solutions that have strong reducing agents It should not be used in solutions that contain proteins, sulphide or bromide

It can be used in places or solutions that have strong reducing agent

While using reference electrodes, the internal liquid level should always be kept above that of the sample solution. True False

True

Which of the following salt bridge solutions must be used for silver/silver chloride electrode? Saturated KCl Saturated K2SO4 Saturated LiCl Saturated KNO3

Saturated KCl

LiCl salt bridge is more suitable in organic solvents than KCl. True False

True

pH meters can be considered as voltage sources with which of the following internal resistances? Very low resistance Moderate resistance Very high resistance No resistance

Very high resistance

The electrodes used in pH measurement have which of the following internal resistances? Very low resistance Moderate resistance Very high resistance No resistance

Very high resistance

Which of the following is not a failure in pH meters? Defective electrodes Defective input circuitry Defective electronic circuitry Defective calibration

Defective calibration

Which of the following is the simplest of pH meters? Null-detector type pH meter Direct reading type pH meter Digital pH meter Modern pH meter

Null-detector type pH meter

In which of the following ways can zero drift be reduced in pH meters? Using filter Giving zero adjustment arrangement Keeping the input impedance high Using balanced and differential amplifiers

Using balanced and differential amplifiers

Which of the following can be used to provide automatic temperature compensation? Proper insulation Calibration for different temperatures Thermistor Thermometer

Thermistor

Which of the following is not the characteristic of null-detector type pH meter? It can be battery operated It has less accuracy It is easy to maintain Its electronic circuits are simple

Its electronic circuits are simple

Which of the following is not the characteristic of direct reading type pH meters? Simple operation Quick to use Continuous indication output It requires balancing process

Quick to use

Which of the following is not the characteristic of chopper amplifier pH meter? Direct voltage from the electrodes is chopped at the main frequency Using choppers for high-input resistance gives rise to spikes of waveforms at the output It leads to stability in DC output of phase-sensitive rectifier Magnitude of surge increases in the glass electrode output

It leads to stability in DC output of phase-sensitive rectifier

In which of the following ways can the disadvantages of chopper amplifier type pH meter be overcome? Using zero corrected DC amplifier Using modern design Using digital design Using vibrating condenser

Using vibrating condenser

The zero stability of vibrating condenser amplifier type pH meter is much better than direct coupled amplifier. True False

True

In vibrating condenser amplifier type pH meter, to maintain good performance which of the following has to be done? Frequency of the vibrator should be stable Frequency of the vibrator should be constant Amplitude of the vibrator should be constant Both frequency and amplitude of the vibrator should be constant and stable

Both frequency and amplitude of the vibrator should be constant and stable

If an instrument fails to balance at zero, it is most likely that the electrodes are defective. True False

False

Given below is the block diagram of digital pH meter. Identify the unmarked component. Filter Buffer A/D converter D/A converter

A/D converter

Which of the following is not the characteristic of ion selective electrodes? It is fragile Easy to use Available in different sizes and shapes It is insensitive to many ions

It is fragile

In glass membrane electrode, the glass containing 11% Na2O, 18% Al2O3, 71% SiO2 is highly sensitive to which of the following ions? Sodium Hydrogen Nitrogen Chlorine

Sodium

In liquid membrane electrode, the liquid ion exchanger is held in a porous disc of _____________ Solid material Semi-permeable membrane Hydrophobic material Water absorbing material

Hydrophobic material

In recent liquid membrane electrodes, the porous liquid membrane is replaced with which of the following? Polyvinyl chloride Polyacryl chloride Polyester membrane Polyacryl amide

Polyvinyl chloride

Which of the following is used in potassium electrode in liquid membrane electrodes? Ionomycin Valinomycin Nonactin Gramicidin

Valinomycin

In solid state membranes, the body of the electrodes are made of which of the following? Polyvinyl chloride Plastic Polythene Teflon

Teflon

Which of the following is not the characteristic of ion selective electrodes? Simple to use Inexpensive Narrow concentration range Operates in wide range of temperature

Narrow concentration range

Ion selective electrode are unaffected by colour or turbidity of the solution. True False

True

Which of the following is not a problem of ion selective electrodes? Interference with other ions Output is influences by ionic strength Drift in electrode potential during a sequence of measurements Can measure only positive ions

Can measure only positive ions

Which of the following is the effective concentration measured at the electrode head? Selectivity co-efficient Ionic strength Activity Activity co-efficient

Activity

The value of activity co-efficient is always in which of the following ranges? Zero Less than zero Less than 1 Greater than 1

Greater than 1

Which of the following specifies the relation between ionic strength and activity co-efficient? Directly proportional Inversely proportional Equal No particular relation

Inversely proportional

The difference between measured activity and actual concentration becomes higher at higher concentration. Is this statement true or false? True False

True

Ion selective electrodes have ________ linear range and _________ detection limit than the pH electrode. Lower, lower Lower, higher Higher, lower Higher, higher

Lower, higher

END