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Questions and Answers
Which of the following dictates the movement of ions in a solution when a weak electrical current is applied?
Which of the following dictates the movement of ions in a solution when a weak electrical current is applied?
- The charge of the electrodes (correct)
- The presence of nonelectrolytes
- The viscosity of the solution
- Random Brownian motion
What is the primary context in which milliequivalents (mEq) are used?
What is the primary context in which milliequivalents (mEq) are used?
- Calculating the volume of a chemical reaction
- Measuring gas pressure in industrial processes
- Determining the pH of a solution
- Expressing the concentration of electrolytes in solution (correct)
What does the valence of ions signify in the context of milliequivalents?
What does the valence of ions signify in the context of milliequivalents?
- The ion's solubility in water
- The total number of ionic charges in solution (correct)
- The hydration status of the ion
- The ion's atomic mass
If a solution contains 50 mEq of $K^+$ ions per liter, what can be definitively stated about the $Cl^-$ ion concentration if potassium chloride (KCl) is the only solute?
If a solution contains 50 mEq of $K^+$ ions per liter, what can be definitively stated about the $Cl^-$ ion concentration if potassium chloride (KCl) is the only solute?
A milliequivalent is defined as which of the following?
A milliequivalent is defined as which of the following?
What is the equivalent weight of a substance, given its atomic or formula weight and valence?
What is the equivalent weight of a substance, given its atomic or formula weight and valence?
If the molecular weight of $\text{NH}_4\text{Cl}$ is 53.5, what is the mass of $\text{NH}_4\text{Cl}$ required to prepare 100 mEq per liter?
If the molecular weight of $\text{NH}_4\text{Cl}$ is 53.5, what is the mass of $\text{NH}_4\text{Cl}$ required to prepare 100 mEq per liter?
A solution contains 20 mg/100 mL of $K^+$ ions. If the atomic weight of $K^+$ is 39, what is this concentration in terms of milliequivalents per liter (mEq/L)?
A solution contains 20 mg/100 mL of $K^+$ ions. If the atomic weight of $K^+$ is 39, what is this concentration in terms of milliequivalents per liter (mEq/L)?
How many milliequivalents of $Na^+$ are present in a 50-mL dose of a solution containing 24 g of disodium hydrogen phosphate ($Na_2HPO_4 \cdot 7H_2O$) and 72 g of sodium biphosphate ($NaH_2PO_4 \cdot H_2O$) per 100 mL?
How many milliequivalents of $Na^+$ are present in a 50-mL dose of a solution containing 24 g of disodium hydrogen phosphate ($Na_2HPO_4 \cdot 7H_2O$) and 72 g of sodium biphosphate ($NaH_2PO_4 \cdot H_2O$) per 100 mL?
What is the defining characteristic of a 'mole' in chemistry?
What is the defining characteristic of a 'mole' in chemistry?
What value does the Standard International (SI) system use to express electrolyte concentrations?
What value does the Standard International (SI) system use to express electrolyte concentrations?
Calculate the approximate number of millimoles present in 250 g of a substance with a molecular weight of 50.
Calculate the approximate number of millimoles present in 250 g of a substance with a molecular weight of 50.
If blood plasma levels of a drug are 1.0 µg/mL, what is this concentration in µmol/L given the drug's molecular weight is 500?
If blood plasma levels of a drug are 1.0 µg/mL, what is this concentration in µmol/L given the drug's molecular weight is 500?
Which property is directly proportional to the total number of particles in a solution?
Which property is directly proportional to the total number of particles in a solution?
What distinguishes osmolarity from osmolality?
What distinguishes osmolarity from osmolality?
What is the osmolarity of a 1 mmol solution of $CaCl_2$ assuming complete dissociation?
What is the osmolarity of a 1 mmol solution of $CaCl_2$ assuming complete dissociation?
A 1.8% solution of sodium chloride (NaCl) is prepared. Given the formula weight of NaCl is 58.5, what is the approximate osmolarity of this solution?
A 1.8% solution of sodium chloride (NaCl) is prepared. Given the formula weight of NaCl is 58.5, what is the approximate osmolarity of this solution?
Which scenario would result in the highest degree of dissociation in an electrolyte solution?
Which scenario would result in the highest degree of dissociation in an electrolyte solution?
What is the milliequivalent per liter concentration of a solution containing 0.05 M of $Ca^{2+}$?
What is the milliequivalent per liter concentration of a solution containing 0.05 M of $Ca^{2+}$?
In a parenteral fluid containing 77 mEq of $Na^+$, 20 mEq of $K^+$, and chloride ions, if the molecular weight of anhydrous dextrose is 180, how many millimoles of anhydrous dextrose are present if 50 g are used in the solution?
In a parenteral fluid containing 77 mEq of $Na^+$, 20 mEq of $K^+$, and chloride ions, if the molecular weight of anhydrous dextrose is 180, how many millimoles of anhydrous dextrose are present if 50 g are used in the solution?
A solution is prepared by dissolving 10 g of NaCl (molecular weight = 58.5 g/mol) in enough water to make 1 liter of solution. Assuming complete dissociation, what is the approximate osmolarity of this solution?
A solution is prepared by dissolving 10 g of NaCl (molecular weight = 58.5 g/mol) in enough water to make 1 liter of solution. Assuming complete dissociation, what is the approximate osmolarity of this solution?
Distinguish which of the following solutions would theoretically exhibit the highest osmotic pressure.
Distinguish which of the following solutions would theoretically exhibit the highest osmotic pressure.
Flashcards
Nonelectrolytes
Nonelectrolytes
Substances that do not dissociate into ions when dissolved in a solution.
Electrolytes
Electrolytes
Substances that dissociate into ions when dissolved in a solution, allowing the solution to conduct electricity.
Cations
Cations
Positively charged ions that move towards the cathode (negative electrode).
Anions
Anions
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Acid-base Balance
Acid-base Balance
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Milliequivalent (mEq)
Milliequivalent (mEq)
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Milliequivalent
Milliequivalent
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Mole
Mole
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Milliosmole (mOsmol)
Milliosmole (mOsmol)
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Osmotic Pressure
Osmotic Pressure
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Osmolarity
Osmolarity
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Osmolality
Osmolality
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Study Notes
- Electrolyte solutions involve milliequivalents, millimoles, and milliosmoles.
- Electrolytes include potassium, calcium, chloride, magnesium, and sodium ions.
Electrolytes vs. Nonelectrolytes
- Nonelectrolytes do not dissociate in solutions, for example, urea and dextrose.
- Electrolytes dissociate in solutions to varying degrees, for example, sodium chloride.
- Sodium chloride in water yields Na+ and Cl- ions, which carry electric charges.
- In an electric field, Na+ ions (cations) move to the negative electrode (cathode).
- Cl- ions (anions) move to the positive electrode (anode).
Electrolytes in Body Fluids
- Electrolytes play a role in maintaining acid-base balance.
- They are involved in controlling body water volumes.
- They help regulate body metabolism.
- Electrolytes are provided as oral solutions or syrups.
- They are also available as dry granules, tablets, capsules, or intravenous infusions.
Milliequivalent (mEq)
- Milliequivalent (mEq) is used to express electrolyte concentrations in solution, especially in the United States.
- A milliequivalent is related to the total number of ionic charges in solution.
- It takes valence of the ions into consideration.
- It expresses the amount of chemical activity of an electrolyte.
- For a chemical compound, the milliequivalents of cation equals milliequivalents of anion.
- Blood plasma contains 154 mEq of cations and the same number of anions.
- If potassium chloride is dissolved in water to give 40 mEq/L of K+, there will be 40 mEq/L of Cl-.
- Milliequivalent represents the amount in milligrams of a solute equal to 1/1000 of its gram equivalent weight.
- The calculation accounts for the valence of ions.
- mEq = (mg x Valence) / (Atomic, Formula, or Molecular Weight)
- mg = (mEq x Atomic, Formula, or Molecular Weight) / Valence
- mg/mL = (mEq/mL x Atomic, Formula, or Molecular Weight) / Valence
- Equivalent weight = Atomic or formula weight / Valence
- mEq = 1/1000 x g eq wt
- Example calculation: Concentration of a solution containing 2 mEq of KCl per milliliter is calculated to be 149 mg/mL.
- Molecular weight of KCl = 74.5
- Equivalent weight of KCl = 74.5
- 1 mEq of KCl = 1/1000 × 74.5 g
- A solution containing 4 mEq of calcium chloride (CaCl2·2H2O) has a concentration of 0.294 g/mL.
- The percent (w/v) concentration of a solution containing 100 mEq of ammonium chloride per liter is 0.535%.
- A solution containing 10 mg/100 mL of K+ ions has a concentration of 2.56 mEq/L.
- 16.7 mEq of magnesium sulfate in 1 g of anhydrous magnesium sulfate is reppresented
Sample Problem Calculation
- Disodium hydrogen phosphate and Sodium biphosphate solution contains 144.6 mEq of Na+.
- Formula for Disodium hydrogen phosphate is Na2HPO4.7H2O.
- Formula for Sodium biphosphate is NaH2PO4.H2O.
Millimoles and Micromoles
- The SI system expresses electrolyte concentrations in millimoles per liter (mmol/L).
- One mole is the molecular weight of a substance in grams.
- Monobasic sodium phosphate (m.w. 138) in 100 g of the substance has 725 mmol.
- Blood plasma levels of 0.5 µg/ml is equal to 1.07 µmol/L.
- Blood plasma levels of 2µg/ml. is equal to 4.28 µmol/L.
Osmolarity
- Osmotic pressure is proportional to the total number of particles in a solution.
- Milliosmole (mOsmol) is the unit to measure osmotic concentration.
- For dextrose, 1 mmol equals 1 mOsmol.
- For electrolytes, the total number of particles depends on the degree of dissociation.
- 1 mmol of NaCl dissociates into 2 mOsmol (Na+ + Cl-).
- 1 mmol of CaCl2 dissociates into 3 mOsmol (Ca++ + 2Cl-).
- Osmolarity is milliosmoles of solute per liter of solution.
- Osmolality is the milliosmoles of solute per kilogram of solvent.
- For dilute aqueous solutions, osmolarity and osmolality are nearly identical.
- Osmometers are used to measure osmolality.
- Solution of sodium chloride at 0.9% has the concentration of 308 mOsmol.
Calculation Sample Fluid
- A parenteral fluid containing dextrose, sodium chloride KCl, and water has:
- 77 mEq of Na+
- 77 mEq of Cl-
- 20 mEq of K+
- 97 mEq of Cl-
- 20 mEq of K+
- 278 mmol of dextrose
- 472 mOsmol
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