HA: Procedure 5.5: Solution and Dilution work: A. Calculate how much stock solut

Question

HA: Procedure 5.5: Solution and Dilution work: A. Calculate how much stock solution and how much water are needed to prepare 350 ml of a 40 ml solution given a stock solution of 2mg/ml. B. A 3% fructose solution was created in 100 ml of water. For this solution calculate the number of grams, milligrams and micrograms in the solution. 3% fructose solution = g/100 ml g /ml mg/ ml g / ml Using the atomic weight of fructose of 180.16 g/mol. What is the molarity (moles/L) of the above solution? C. You need to make a dilution of an over-the-counter liquid medicine according to your pet dog's weight. The medicine comes in a stock solution of 150 mg/ml. The recommended dose for a 100 pound dog is 150 mg. However, your dog only weighs 18 pounds. Calculate the correct dose for your dog (hint: use a ratio) in milligrams. You would like to give your pet dog 1ml total volume of medicine. To obtain the correct dose, how much medicine and how much water do you need to mix? You have micropipettes at your disposal and would like to give your pet dog the correct dose. ml of 150 mg/ml medicine ml of water 12

Explanation / Answer

A. stock solution: 2mg/ml = 2000g/ml

   working solution= 40g/ml

thus 2000g is in 1ml

so 40 g will be in 40/ 2000=0.02 ml or 20l

thus to prepare 350ml, take 0.2 ml from stock solution and 349.98ml of water.

B. 3% fructose solution means 3 gm of fructose in 100ml

3gm/100ml

=0.03g/ml

=30mg/ml ( as 1g= 1000mg)

=30000ug/ml

Molecular weight of sucrose is 180.16g/mol

or 1000ml 1M solution of sucrose contains 180.16 gm

180.16gm= 1M

thus 3 gm = 3/ 180.16=0.0166M

now, 1000ml of soluiton is 0.0166M

therefoe, 100ml of solution will be 0.0166 X 100 / 1000 =0.00166M or 1.66mM.

c. Stock solution of the medicine is 150mg/ml

recomended dose is 150 mg for 100 pound.

so body weight to medicine ratio is 150:100= 1.5

thus if the pet is 18 pound , the required dose will be 18 X 1.5 mg= 27 mg

now, the stock solution is 150mg/ml

to make it 27mg /ml we need to dilute the medicine 150/27=5.5 times.

for a 1ml solution, 1/5.5 or approximately 0.180 ml of medicine is required.

0.180ml of medicine from 100mg/ml

0.820 ml of water is required.

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