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Question 1 of 6

A preparation calls for 350 ml of 80 % Ethanol. What volume of Ethanol (96 per cent) BP do you need for the preparation? Answer to 1 decimal place.

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millilitres
You need 290.8 ml of Ethanol (96 per cent) BP.
Ethanol (96 per cent) BP contains 96.0 to 96.6 % Ethanol giving an average of 96.3 %.
Concentration1 x Quantity1 = Concentration2 x Quantity2
  96.3          x Quantity1 =            80          x    350
     Quantity1 =    28000    ml
96.3
Quantity1 = 290.75 ml
Quantity1 = 290.8 ml to 1 dec pl
Formula:
290.8 ml Ethanol (96 per cent) BP to      350 ml    Water

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Question 2 of 6

How many grams of Formaldehyde Solution BP (34-38%, density 1.08 g/ml) are needed to prepare 600 ml of a 8 % solution of Formaldehyde?

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g
You need 144 grams of Formaldehyde Solution BP.
  1. Find the weight of 600 ml of the 8 % W/W solution of Formaldehyde.
    Formaldehyde Solution BP has a density of about 1.08 g/ml. You can assume that the 8 % solution also has a density of about 1.08 g/ml. Thus 1 ml of the 8 % solution weighs 1.08 g. Thus:
    600 ml of the 8 % solution weighs 600 x 1.08 g = 648 g
    You need to prepare 648 g of the 8 % solution.
  2. Find the mass of Formaldehyde Solution BP needed.
    The concentration of Formaldehyde Solution BP is 34-38 % giving an average of 36 %. Using the equation: Concentration1 x Quantity1 = Concentration2 x Quantity2
    36          x Quantity1 =             8           x      648
    Quantity1 =   5184   g = 144 g
    36
    You need 144 grams of Formaldehyde Solution BP.

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Question 3 of 6

An infusion bag has a volume of 500 ml. You need to prepare one infusion bag containing a solution of Potassium Chloride (RMM 74.6) with a concentration of 0.02 millimoles per millilitre. You must prepare the solution from a 15 % (w/v) solution of Potassium Chloride. How many millilitres of the 15 % solution do you need? Answer to 2 decimal places.

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millilitres
You need 4.97 ml of 15 % Potassium Chloride.
  1. Find the required concentration as a percent weight in volume.
    0.02 millimoles per millilitre = 2 millimoles per 100 millilitres
    = 0.002 moles per 100 millilitres
    Mass of KCl in 100 ml of solution = Moles x RMM = 0.002 x 74.6 = 0.1492 g
    The required concentration is 0.1492 g/100 ml ie 0.1492 % w/v.
  2. Find the volume of 15 % Potassium Chloride needed.
    Concentration1 x Quantity1 = Concentration2 x Quantity2
        15          x Quantity1 =        0.1492       x    500
       Quantity1 =    74.6    ml
    15
    Quantity1 = 4.973 ml = 4.97 ml to 2 dec pl

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Question 4 of 6

A preparation calls for 400 ml of 55 % Ethanol. You only have available 80 % Ethanol. How many millilitres of Ethanol do you need to prepare the 55 % Ethanol?

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ml
You need 275 ml of 80 % Ethanol.
Concentration1 x Quantity1 = Concentration2 x Quantity2
  80          x Quantity   =            55          x    400
     Quantity1 =    22000    ml
80
Quantity1 =     275 ml
Formula:
275 ml 80 % Ethanol to   400 ml Water

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Question 5 of 6

A preparation needs 250 ml of 6 % Formalin. You have available Formaldehyde Solution BP 1988 (34-38 %, density 1.08 g/ml). How much Formaldehyde Solution BP 1988 do you need?

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ml
You need 15 ml of Formaldehyde Solution BP.
  1. A 6 % solution of Formalin is the same as a 6 % v/v solution of Formaldehyde Solution BP 1988.
  2. Find the volume of Formaldehyde Solution needed.
    Concentration1 x Quantity1 = Concentration2 x Quantity2
    Since you are diluting Formaldeyde Solution BP itself, Concentration1 is 100 %.
       100           x Quantity1 =           6           x      250
    Quantity1 =   1500   ml
    100
    Quantity1 = 15 ml
    Formula:
    15 ml    Formaldehyde Solution BP to   250 ml Water

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Question 6 of 6

The antiseptic Chlorhexidine Gluconate is available commercially as a 20 % w/v solution. Chlorhexidine Gluconate is issued as a 0.4 % solution. How many millilitres of the commercial product do you need to prepare 5 litres of 0.4 % solution?

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millilitres
You need 100 ml of the commercial product.
Concentration1 x Quantity1 = Concentration2 x Quantity2
  20          x Quantity1 =            0.4          x    5000
Quantity1 =    2000    ml
20
Quantity1 = 100 ml
Formula:
100 ml Chlorhexidine Gluconate (20 %) to   5000 ml Water

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