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Questions and Answers
What type of reaction occurs at the cathode of an electrolytic cell?
What type of reaction occurs at the cathode of an electrolytic cell?
In an electrolytic cell, which statement about the electrodes is true?
In an electrolytic cell, which statement about the electrodes is true?
What is required to initiate the reaction in an electrolytic cell?
What is required to initiate the reaction in an electrolytic cell?
What happens to electrons in a galvanic cell?
What happens to electrons in a galvanic cell?
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Which of the following best describes an electrolytic cell?
Which of the following best describes an electrolytic cell?
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At the anode of an electrolytic cell, what type of reaction occurs?
At the anode of an electrolytic cell, what type of reaction occurs?
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What distinguishes a galvanic cell from an electrolytic cell?
What distinguishes a galvanic cell from an electrolytic cell?
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What is the primary function of a salt bridge in an electrochemical cell?
What is the primary function of a salt bridge in an electrochemical cell?
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In a redox reaction, what happens to the species that is oxidized?
In a redox reaction, what happens to the species that is oxidized?
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What happens to the net voltage of an electrochemical cell when equilibrium is reached?
What happens to the net voltage of an electrochemical cell when equilibrium is reached?
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Which of the following statements best describes primary cells?
Which of the following statements best describes primary cells?
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In a standard Daniell Cell, what is the role of the zinc electrode?
In a standard Daniell Cell, what is the role of the zinc electrode?
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Which process is responsible for the production of electrical energy in galvanic cells?
Which process is responsible for the production of electrical energy in galvanic cells?
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What defines an electrode's potential in an electrochemical cell?
What defines an electrode's potential in an electrochemical cell?
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Which statement accurately describes the flow of electrons in an electrochemical cell?
Which statement accurately describes the flow of electrons in an electrochemical cell?
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What characterizes secondary cells compared to primary cells?
What characterizes secondary cells compared to primary cells?
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Which process occurs at the electrode connected to the positive terminal in an electrolytic cell?
Which process occurs at the electrode connected to the positive terminal in an electrolytic cell?
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What is the function of ion-selective electrodes (ISE) in analytical chemistry?
What is the function of ion-selective electrodes (ISE) in analytical chemistry?
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What distinguishes an electrolytic cell from a galvanic cell?
What distinguishes an electrolytic cell from a galvanic cell?
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Which characteristic is NOT associated with ion-selective-membrane electrodes?
Which characteristic is NOT associated with ion-selective-membrane electrodes?
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How do ion-selective electrodes generate a potential difference?
How do ion-selective electrodes generate a potential difference?
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What is the role of the reference electrode in potentiometry?
What is the role of the reference electrode in potentiometry?
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Why are ion-selective electrodes considered transducers?
Why are ion-selective electrodes considered transducers?
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In potentiometry, what type of voltmeter is used to measure the potential between two electrodes?
In potentiometry, what type of voltmeter is used to measure the potential between two electrodes?
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What is the main function of sodium in the body?
What is the main function of sodium in the body?
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Which hormone is primarily responsible for the adjustment of sodium levels in the body?
Which hormone is primarily responsible for the adjustment of sodium levels in the body?
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What is the normal range of serum sodium levels in adults?
What is the normal range of serum sodium levels in adults?
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What can occur if serum sodium levels drop below 125 mEq/L?
What can occur if serum sodium levels drop below 125 mEq/L?
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Which condition is characterized by a serum sodium level of less than 150 mmol/L?
Which condition is characterized by a serum sodium level of less than 150 mmol/L?
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Which of the following ions can be measured using ion selective electrodes?
Which of the following ions can be measured using ion selective electrodes?
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What does an increase in serum sodium above 152 mEq/L typically cause?
What does an increase in serum sodium above 152 mEq/L typically cause?
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What is the typical sodium excretion range in urine over 24 hours?
What is the typical sodium excretion range in urine over 24 hours?
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What potassium level indicates critical values that can cause muscle irritability, including myocardial irritability?
What potassium level indicates critical values that can cause muscle irritability, including myocardial irritability?
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Which scenario is most likely to result in a spurious hyperkalemia reading?
Which scenario is most likely to result in a spurious hyperkalemia reading?
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What is the recommended anticoagulant of choice for potassium analysis?
What is the recommended anticoagulant of choice for potassium analysis?
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Which of the following is NOT a reason for artifactual hyperkalemia during potassium analysis?
Which of the following is NOT a reason for artifactual hyperkalemia during potassium analysis?
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What is the acceptable 24-hour urinary potassium output range for analysis?
What is the acceptable 24-hour urinary potassium output range for analysis?
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What can lead to an elevated serum K+ concentration after blood collection?
What can lead to an elevated serum K+ concentration after blood collection?
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Why is it important to analyze serum and plasma potassium levels promptly after collection?
Why is it important to analyze serum and plasma potassium levels promptly after collection?
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Which potassium level range indicates normal serum potassium concentrations in adults?
Which potassium level range indicates normal serum potassium concentrations in adults?
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Study Notes
Electrochemical Cells
- Electrochemical cells are devices that convert chemical energy into electrical energy or vice versa.
- They consist of two half-cells, each containing an electrode and an electrolyte.
- The half-cells are connected by a salt bridge, which allows ionic contact without mixing the electrolytes.
- Oxidation (loss of electrons) occurs at the anode, and reduction (gain of electrons) occurs at the cathode.
- The potential difference between the electrodes is called the cell potential or electromotive force (EMF).
Galvanic Cells (Voltaic Cells)
- Convert chemical energy into electrical energy via spontaneous redox reactions.
- The anode is negative and the cathode is positive.
- Electrons flow from the anode to the cathode through an external circuit.
- A common example is the Daniell cell, which consists of a zinc anode in a zinc sulfate solution and a copper cathode in a copper sulfate solution.
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Example Daniell cell:
- Anode: Zinc metal electrode, Zn(s) in 1 mol L-1 ZnSO4(aq)
- Cathode: Copper metal electrode, Cu(s) in 1 mol L-1 CuSO4(aq)
- Oxidation reaction: Zn(s) → Zn2+(aq) + 2e-
- Reduction reaction: Cu2+(aq) + 2e- → Cu(s)
Electrolytic Cells
- Convert electrical energy into chemical energy via non-spontaneous redox reactions.
- An external power source is required to drive the reaction.
- The anode is positive and the cathode is negative.
- Electrons flow from the external power source through the cathode to the anode.
- Electrolytic cells are used in processes like electroplating and electrolysis.
Potentiometry
- A technique used in analytical chemistry to measure the concentration of a solute in solution.
- It involves measuring the potential difference between two electrodes, one of which is ion-selective.
- Ion-selective electrodes (ISEs) are widely used analytical tools for detecting specific ions in various samples.
- ISEs convert the activity of a specific ion into an electrical potential.
Ion-Selective Electrodes (ISEs)
- Electrochemical sensors that work based on the principle of a galvanic cell.
- They generate a potential in response to the presence of a specific ion in solution.
- They consist of a membrane that allows only the specific ion to pass through, creating a potential difference that is proportional to the concentration of the ion.
- ISEs have various applications in clinical, industrial, environmental, and research settings.
Sodium (Na+)
- The major extracellular cation, playing a crucial role in water balance and osmotic pressure.
- Serum sodium levels are used to diagnose various conditions related to water balance, electrolyte imbalances, and acid-base balance.
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Normal values:
- Adults: 136–145 mEq/L (136–145 mmol/L)
- Children (1–16 years): 136–145 mEq/L (136–145 mmol/L)
- Full-term infants: 133–142 mEq/L (133–142 mmol/L)
- Premature infants: 132–140 mEq/L (132–140 mmol/L)
- In urine (24h): 40-220 mmol/day.
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Critical values:
- < 125 mEq/L (_125 mmol/L) causes weakness and dehydration.
- 90–105 mEq/L (90–105 mmol/L) causes severe neurologic symptoms and vascular problems.
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152 mEq/L (_152 mmol/L) results in cardiovascular and renal symptoms.
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160 mEq/L (_160 mmol/L) can cause heart failure.
Potassium (K+)
- Major intracellular cation, crucial for muscle function, nerve impulse transmission, and maintaining normal heart rhythm.
- Serum potassium levels are used to diagnose various conditions related to electrolyte imbalances, kidney function, and metabolic disorders.
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Normal values:
- Adults: 3.5–5.2 mEq/L (3.5–5.2 mmol/L)
- Children (1–18 years): 3.4–4.7 mEq/L (3.4–4.7 mmol/L)
- Infants: (7 days–1 year): 4.1–5.3 mEq/L (4.1–5.3 mmol/L)
- Neonates (0–7 days): 3.7–5.9 mEq/L (3.7–5.9 mmol/L)
- In urine (24h): 25-125 mmol/day.
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Critical values:
- 8.0 mEq/L (_8.0 mmol/L) causes muscle irritability, including myocardial irritability.
Hypokalemia
- A decrease in serum potassium below the normal range (less than 3.5 mmol/L),
- May be caused by various factors, including decreased intake, increased renal excretion, or cellular redistribution.
- Can lead to muscle weakness, fatigue, cramps, and abnormal heart rhythms.
Hyperkalemia
- An increase in serum potassium above the normal range (over 5.5 mmol/L),
- May be caused by factors such as impaired kidney function, excessive potassium intake, or certain medications.
- Can lead to muscle weakness, paralysis, and potentially life-threatening heart rhythm abnormalities.
Proper sample handling for potassium measurement:
- Avoid hemolysis as this releases K+ from erythrocytes falsely elevating the result.
- Heparin is preferred anticoagulant for potassium testing.
- Platelet counts should be considered as thrombocytosis can lead to false hyperkalemia.
- Sample storage should be at room temperature and analyzed promptly or centrifuged to remove the cells.
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Description
Explore the fascinating world of electrochemical cells and their applications in converting chemical energy into electrical energy. This quiz covers the structure of galvanic cells, their components, and the fundamental processes of oxidation and reduction. Test your understanding of key concepts like cell potential and specific examples such as the Daniell cell.
