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Questions and Answers
How is a percent solution defined in terms of components by weight?
How is a percent solution defined in terms of components by weight?
If making a 5% (w/w) aqueous solution of hydrochloric acid, what principle is being used?
If making a 5% (w/w) aqueous solution of hydrochloric acid, what principle is being used?
What volume of HCl is needed to prepare 50 mL of a 2% (v/v) solution?
What volume of HCl is needed to prepare 50 mL of a 2% (v/v) solution?
When preparing a percent solution, which of the following is necessary to ensure accuracy?
When preparing a percent solution, which of the following is necessary to ensure accuracy?
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What is the effect of molecular weight when expressing percent solutions?
What is the effect of molecular weight when expressing percent solutions?
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What happens when the ratio of [A−] to [HA] is equal to 1?
What happens when the ratio of [A−] to [HA] is equal to 1?
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What is the term used to describe the dissociation constant of a weak acid?
What is the term used to describe the dissociation constant of a weak acid?
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Which factor influences the buffering capacity of a solution?
Which factor influences the buffering capacity of a solution?
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What effect does increasing ionic strength have in a buffer solution?
What effect does increasing ionic strength have in a buffer solution?
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What will occur if the dissociation constant Ka of a weak acid is very small?
What will occur if the dissociation constant Ka of a weak acid is very small?
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In buffer solutions, how is the conjugate base often referenced?
In buffer solutions, how is the conjugate base often referenced?
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Which equation can be used to calculate the dissociation constant Ka of a weak acid?
Which equation can be used to calculate the dissociation constant Ka of a weak acid?
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What condition is necessary for a weak acid to achieve maximum buffering capacity?
What condition is necessary for a weak acid to achieve maximum buffering capacity?
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What is the primary purpose of TC devices in laboratory settings?
What is the primary purpose of TC devices in laboratory settings?
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How is a temperature in Celsius converted to Fahrenheit?
How is a temperature in Celsius converted to Fahrenheit?
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What type of glass is commonly used for disposable materials in laboratories?
What type of glass is commonly used for disposable materials in laboratories?
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Which of the following statements about temperature-dependent reactions is correct?
Which of the following statements about temperature-dependent reactions is correct?
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Which glassware category is specifically known for its resistance to acid and alkali?
Which glassware category is specifically known for its resistance to acid and alkali?
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What characterizes plasticware compared to traditional glassware in laboratory settings?
What characterizes plasticware compared to traditional glassware in laboratory settings?
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Which type of glassware should ideally be used for enzyme determinations requiring precise temperature control?
Which type of glassware should ideally be used for enzyme determinations requiring precise temperature control?
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What is a common use of a heating/cooling cell in laboratory practices?
What is a common use of a heating/cooling cell in laboratory practices?
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What is a primary advantage of using automatic pipettes?
What is a primary advantage of using automatic pipettes?
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Which type of pipette is described as being able to select different volumes?
Which type of pipette is described as being able to select different volumes?
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What is a characteristic of micropipettes?
What is a characteristic of micropipettes?
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In what situation should disposable transfer pipettes be used?
In what situation should disposable transfer pipettes be used?
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What does the term 'automatic' imply when referring to automatic pipettes?
What does the term 'automatic' imply when referring to automatic pipettes?
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What defines a fixed volume pipette?
What defines a fixed volume pipette?
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What type of pipette can dispense fluid to multiple wells at once?
What type of pipette can dispense fluid to multiple wells at once?
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What defines an automatic macropipette?
What defines an automatic macropipette?
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How should you properly prepare a solution when adding acid to water?
How should you properly prepare a solution when adding acid to water?
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What is the definition of molarity (M)?
What is the definition of molarity (M)?
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What is a common method for calculating the amount of substance needed for a percent solution?
What is a common method for calculating the amount of substance needed for a percent solution?
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What amount of concentrated HCl is needed to make the solution as described?
What amount of concentrated HCl is needed to make the solution as described?
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What is the meaning of the term 10% (w/v) solution?
What is the meaning of the term 10% (w/v) solution?
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Which solution is a 5% aqueous solution typically calculated from?
Which solution is a 5% aqueous solution typically calculated from?
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What should be done after mixing concentrated HCl with water according to the preparation instructions?
What should be done after mixing concentrated HCl with water according to the preparation instructions?
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What is the equivalent of 1 mol of a substance in terms of grams?
What is the equivalent of 1 mol of a substance in terms of grams?
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Study Notes
Vessel Designations
- TC (Contain) vessels do not deliver measured volume; TD (Deliver) vessels dispense the specified amount.
- Accuracy in delivering liquid is crucial for laboratory processes, especially during transfers.
Temperature Conversion
- Convert Celsius to Fahrenheit using the formula: °F = (°C × 9/5) + 32.
- Convert Fahrenheit to Celsius with: °C = (°F - 32) × 5/9.
Types of Laboratory Glassware
- Common glass types:
- Kimax/Pyrex (borosilicate)
- Corex (aluminosilicate)
- High silica glass
- Vycor (acid/alkali resistant)
- Low actinic (amber colored)
- Flint (soda lime glass)
- Clinical chemistry glassware should be high thermal resistance, such as borosilicate or aluminosilicate.
Temperature Control in Reactions
- Optimal temperature is critical for analytic reactions, especially enzyme determinations.
- Various methods exist for heating or cooling samples, such as heating blocks or water baths.
Automatic Pipettes
- Types include fixed volume, variable volume, and multichannel variants.
- Automatic pipettes enhance safety, stability, and ease of use, reducing the necessity for cleaning due to disposable tips.
- Micropipettes handle less than 1 mL; macropipettes manage over 1 mL volumes.
- Multichannel pipettes can dispense fluid to multiple wells simultaneously, improving efficiency in techniques like assay processes.
Weak Acids and Buffers
- Weak acids have minimal dissociation compared to strong acids; described using the Henderson-Hasselbalch equation.
- The equation includes dissociation constant (Ka) for weak acids, also expressed as pKa.
- Buffer capacity is greatest when the concentration ratio of conjugate base ([A−]) to weak acid ([HA]) is 1.
Ionic Strength and Buffers
- Ionic strength influences buffer behavior, particularly in analytical separation techniques.
- Higher ionic strength decreases particle migration rates, affecting separation efficiency.
Preparing Percent Solutions
- Percent solutions denote concentration as "parts per 100" (e.g., % w/v).
- Weight/volume (% w/v), volume/volume (% v/v), and weight/weight (% w/w) are methods to express concentrations.
- Example procedure for a weight/volume (w/v) solution:
- To create a 10% NaOH solution: Determine grams of NaOH needed for 1000 mL of solution.
Calculation Approaches
- Percent solutions can be calculated using either direct fraction multiplication or ratios, depending on the desired final volume.
- Always add acid to water when diluting to ensure safety.
Molarity
- Molarity expresses concentration as moles per liter (mol/L) or millimoles per milliliter (mmol/mL).
- Conversion from weight to molarity requires understanding molar mass and existing concentration units during preparation.
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Description
Test your knowledge on the functionalities of vessels designed for containing or delivering liquids. This quiz also includes a section on converting temperatures from Celsius to Fahrenheit, integrating practical applications in fluid mechanics.
