Calculations Flashcards

1
Q

Fill in the missing values:

A
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2
Q

What names and units go with the following prefix’s?
m
µ
n
p
k

A

m = milli - mmol/ml/mg
µ = micro - µ”/”/”
n = nano - nmol, ng
p = pico - pmol, pg
k = kilo - kg

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3
Q

By how much do the following prefixes modify an amount?
m
µ
n
p
k

A

m = 1/1000 or 10-3
µ = 10-6
n = 10-9
p = 10-12
k = 1000 times or 10x3

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4
Q

What is 1 mole of any substance?

A

Its molecular (or atomic) weight in grams

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5
Q

What triangle can be used to work out the no. of moles (include units)?

A
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6
Q

What is concentration?

What are the 2 most important ways concentration can be expressed?

What units are most commonly used?

A

Concentration = amount of solute dissolved, in a given amount of solvent

Weight in volume e.g. mg/ml
Weight in volume

ml or L (ml usually used for fluids)

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7
Q

What triangle is used when finding concentration (include units)?

A
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8
Q

What is the concentration of NaCl if 50g of NaCl is dissolved in 200ml of water?

A

50g –> mg = 50x1000
50000/200 = 250 mg/ml

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9
Q

You need to make a 40mg/ml solution of glucose. How much water is required to make this solution if you weigh out 5g of glucose?

A

50g -> 5000 mg
5000/40 = 125ml

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10
Q

If there is a 0.9% saline solution how many grams are in 100ml?

A

0.9g
(1% = 1g in 100ml)

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11
Q

What does w/v stand for?

A

Number of grams in a total of 100 ml of solvent

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12
Q

How many grams of sodium chloride are needed to make 2L of 0.9% sodium chloride?

A

0.9 g per 100ml

2L = 2000ml
2000 – 100 = 20
20 x 0.9 = 18g

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13
Q

When are dilutions used?

What do they usually combine?

A

When the amount of compound required is so small, it cannot be accurately measured

A volume of a solution of known concentration (stock solution) with an appropriate volume of solvent

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14
Q

What is the dilution factor?

A

Total number of unit volumes, in which your material is dissolved or how much more concentrated is one solution compared to the other

Example:
a 1 in 5 (1 in a total of 5) dilution means combining 1 volume of the solution with 4 volumes of the solvent
Dilution factor = 1:5
Dilution ratio = 1:4

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15
Q

Sodium chloride is maintained as a stock solution at 20 mg/ml. What is the final concentration of sodium chloride if 2 ml of stock solution is mixed with 8 ml of water?

A

Total volume = 2ml + 8ml = 10ml
DF = 10ml/2ml = 5ml
Final = stock / DF = 20/5 = 4mg/ml

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16
Q

How would you prepare 20 ml of 10mg/ml NaCl solution from a 200mg/ml stock solution?

A

Dilution factor = 200 mg/ml ÷ 10 mg/ml = 20
Total vol / dil. Fac = 20ml /20 = 1 ml stock
20 – 1 = 19 ml water

17
Q

What is a dose?

A

The quantity of drug to be delivered to a patient

18
Q

You need to administer 0.1 mg/kg of a drug to a 400 kg horse. You are using a solution with a concentration of 20 mg/ml. What volume do you need?

A

Volume? Concentration = 20 Mass = 40mg
0.1 x 400 = 40 mg

M=cxv
V = 40/20
V = 2ml

19
Q

A 15 kg dog requires antibiotic capsules for 21 days. The recommended dose is 5 mg/kg every 12 h. Each capsule is 25 mg. How many tablets are needed?

A

75mg every 12 hours
42 x 75 = 3150mg

126 tablets

20
Q

What can the rate of administering intravenous fluids can be determined from?

A
  • volume of fluid needed
  • time of administration
  • number by the drops per millilitre delivered by the giving set
21
Q

An animal requires 1800 ml over 24 h. Using a standard giving set (20 drops/ml). What is the drip rate?

A

20 drops per 1 ml
36000 drops in 24 hours
86,400 seconds in 24hours
84,400/36,400 = 1 drop every 2.4 seconds

22
Q

What is the common unit used for molarity?

23
Q

What triangle can be used to work out the molarity?

24
Q

What is the amount of solute in 250ml of a 1mol.L-1 (1M) solution?

A

250ml = 0.25L
1mol/L x 0.25L = 0.25mol

25
Q

What is the molarity when 4mol is dissolved in 2L of solution?

A

4mol/2L =
2mol.L-1 = 2M