Podcast Beta
Questions and Answers
The difference between the volume of diluted (weaker) solution prepared and the volume of stronger solution used represents the volume of ______ (diluent) to be used.
water
How many milliliters of ______ should be added to a pint of a 5% w/v solution to make a 2% w/v solution?
water
How much ______ should be mixed with 5000 mL of 85% v/v alcohol to make 50% v/v alcohol?
water
The dilution of solids in pharmacy occurs when there is need to achieve a lower concentration of an active component in a more concentrated ______ .
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This may be accomplished by the addition of active ingredient or by the admixture with a calculated quantity of a like-product of greater concentration. 10 Example If a cough syrup contains in each teaspoonful, 1 mg of chlorpheniramine maleate and if a pharmacist desired to double the strength, how many milligrams of that ingredient would need to be added to a 60-mL container of the syrup.Assume no increase in volume. 11 Stock Solutions Stock solutions are concentrated solutions of active (e.g., drug) or inactive (e.g., colorant) substances and are used by pharmacists as a convenience to prepare solutions of lesser concentration. 12 Example Calculations of Stock Solutions How many milliliters of a 1:400 w/v stock solution should be used to make 4 liters of a 1:2000 w/v solution? 13 How many milliliters of a 1:400 w/v stock solution should be used in preparing 1 gallon of a 1:2000 w/v solution. 14 Some interesting calculations are used in pharmacy practice in which the strength of a diluted portion of a solution is defined, but the strength of the concentrated stock solution used to prepare it must be determined. 15 How much drug should be used in preparing 50 mL of a solution such that 5 mL diluted to 500 mL will yield a 1:1000 solution? 1:1000 means 1 g of drug in 1000 mL of solution 16 The accompanying diagrammatic sketch should prove helpful in solving the problem. 17 How many grams of sodium chloride should be used in preparing 500 mL of a stock solution such that 50 mL diluted to 1000 mL will yield a (0.3% w/v) for irrigation? 1000 (mL) × 0.003 = 3 g of sodium chloride in 1000 mL of (0.3% w/v), which is also the amount in 50 mL of the stronger (stock) solution to be prepared. 18 How many milliliters of water should be added to 300 mL of a 1:750 w/v solution of benzalkonium chloride to make a 1:2500 w/v solution?
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The percentage or ratio strength (concentration) of a component in a pharmaceutical preparation is based on its quantity relative to the total quantity of the preparation. If the quantity of the component remains constant, any change in the total quantity of the preparation, through dilution or concentration, changes the concentration of the component in the preparation inversely. An equation useful in these calculations is: (1st quantity) × (1st concentration) = (2nd quantity) × (2nd concentration). The concentration/quantity relationship is based on the principle of ________.
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Stock solutions are concentrated solutions of active (e.g., drug) or inactive (e.g., colorant) substances and are used by pharmacists as a convenience to prepare solutions of lesser concentration. Example Calculations of Stock Solutions: How many milliliters of a 1:400 w/v stock solution should be used to make 4 liters of a 1:2000 w/v solution? Stock solutions are typically used to prepare solutions of ______ concentration.
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Some interesting calculations are used in pharmacy practice in which the strength of a diluted portion of a solution is defined, but the strength of the concentrated stock solution used to prepare it must be determined. How much drug should be used in preparing 50 mL of a solution such that 5 mL diluted to 500 mL will yield a 1:1000 solution? 1:1000 means 1 g of drug in 1000 mL of solution. The accompanying diagrammatic sketch should prove helpful in solving the problem. The strength of the concentrated stock solution used to prepare a diluted portion of a solution must be ________.
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The percentage or ratio strength (concentration) of a component in a pharmaceutical preparation is based on its quantity relative to the total quantity of the preparation. If the quantity of the component remains constant, any change in the total quantity of the preparation, through ______ or concentration, changes the concentration of the component in the preparation inversely. An equation useful in these calculations is: (1st quantity) × (1st concentration) = (2nd quantity) × (2nd concentration) 2 Problems in this section generally may be solved by any of the following methods: 1. Inverse proportion. 2. The equation: (1st quantity)(1st concentration)=(2nd quantity)(2nd concentration), or Q1 C1 = Q2 C2. 3.
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If the quantity of the component remains constant, any change in the total quantity of the preparation, through ______ or concentration, changes the concentration of the component in the preparation inversely.
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An equation useful in these calculations is: (1st quantity) × (1st ______) = (2nd quantity) × (2nd ______) 2 Problems in this section generally may be solved by any of the following methods: 1. Inverse proportion. 2. The equation: (1st quantity)(1st ______)=(2nd quantity)(2nd ______), or Q1 C1 = Q2 C2. 3.
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