math problems

[flowerchildnc]

I am having problems with 3 math problems and need help on how to solve.

1) How many g of licocaine HCl does a patient receive when 23 mL of a 1% solution is administered?

2) 0.33 Sodium Chloride contains _____g of Sodium Chloride per mL.

3) 21.5 mL of 0.25% bupivacaine HCl has been administered to a patient. The patient has received _____g pf bipivacaine HCl.

I know they are probably fairly easy ones but am having trouble....please help.

[Tharem]

When you see a problem with % solution read it as 'grams per 100mL'. So a 1% solution contains 1g of pure drug per 100mL of solution. Using dimensional analysis with the first problem (dots added for formatting):

23mL...X.... 1g ...=....0.23g licocaine HCL

................100mL

The second problem:

0.33 is equal to 33%, or 33g per 100mL, so the problem is:

1mL...X.... 33g ....=....0.33g NaCL

...............100mL

And the last problem is:

21.5mL....X.... 0.25g ....=....0.054g bipivacaine

....................100mL

[Daytonite, BSN, RN]

how many g of lidocaine hcl does a patient receive when 23 ml of a 1% solution is administered?

a 1% solution = 10mg/ml (per my nursing drug handbook)

23ml/

x

mg = 1 ml/10 mg, then

x

= 230, so 23 ml contains 230 mg

230 mg =

0.230 grams

0.33 sodium chloride contains _____g of sodium chloride per ml.

.033% of 1,000 ml = 3.3 grams/liter

this is

0.0033 grams/ml

21.5 ml of 0.25% bupivacaine hcl has been administered to a patient. the patient has received _____g pf bipivacaine hcl.

http://www.drugs.com/pro/bupivacaine.html

- per this reference a 0.25% solution contains 2.5 mg/ml

21.5ml/

x

mg = 1 ml/2.5 mg, then

x

= 53.75, so 21.5 ml contains 53.75 mg

53.75 mg =

0.05375 grams

[Tharem]

0.33 sodium chloride contains _____g of sodium chloride per ml.

.033% of 1,000 ml =

3.3 grams

i think you're mistaken on this. ns only contains about 1g per ml.

[Daytonite, BSN, RN]

I think you're mistaken on this. NS only contains about 1g per mL.

This is not normal saline. Normal saline is 0.9%. I checked my resources. There is no 0.3% saline manufactured that I know of--only 3% which is a hypertonic solution. I did put a % sign on the problem which the OP did not do and would have clarified the entire situation.

[Tharem]

This is not normal saline. Normal saline is 0.9%. I checked my resources. There is no 0.3% saline manufactured that I know of--only 3% which is a hypertonic solution. I did put a % sign on the problem which the OP did not do and would have clarified the entire situation.

But this is a school problem, it doesn't have to correspond to the real world. I assumed the OP stated the problem correctly for that reason. For the data given, the correct answer is 0.33g/mL.

[Daytonite, BSN, RN]

1 liter of 5% Dextrose contains 50 grams of dextrose

.05 x 1000 mL = 50 grams

By the same token a liter of 33% Sodium Chloride would contain

.33 x 1000 = 330 grams

.33% Sodium Chloride would contain 3.3 grams

0.0033 x 1000 = 3.3 grams

1 mL would contain 3.3 grams/1000, or

0.0033 grams

[Tharem]

1 liter of 5% Dextrose contains 50 grams of dextrose

.05 x 1000 mL = 50 grams

By the same token a liter of 33% Sodium Chloride would contain

.33 x 1000 = 330 grams

.33% Sodium Chloride would contain 3.3 grams

0.0033 x 1000 = 3.3 grams

1 mL would contain 3.3 grams/1000, or

0.0033 grams

These are correct, but again, the original problem does not state '.33%', but '0.33'. There is a difference of a factor of 100 between those two values, and that is what is leading to our differing answers. I'm not sure why you feel it's necessary to change the value of the original problem by a factor of 100, but I don't feel comfortable doing that.

[Tharem]

I think you're mistaken on this. NS only contains about 1g per mL.

Correction: NS contains 9mg NaCL per mL, the total mass of 1mL of NS is 1.009g

Daytonite, since NS contains 9mg NaCL per mL, your addition of % to the OP problem makes more sense in the real world, since it would make the solution 3.3mg per mL as opposed to 330mg per mL as in the original problem, which is clearly a fatal value, so it was most likely an error on the OP part, or in the test question itself. Still, the numbers given by the OP lead correctly to 330mg per mL, and if such an answer were marked wrong on my test I would argue it.

[flowerchildnc]

These are school practice test questions for the first math test written as they are on the paper. I do not have the correct answers from school yet. Thanks to everyone for their help with these problems. I think I can set them up and work them out from your information. Thanks again!

[Tharem]

these are school practice test questions for the first math test written as they are on the paper. i do not have the correct answers from school yet. thanks to everyone for their help with these problems. i think i can set them up and work them out from your information. thanks again!

thanks flowerchildnc. i'd be curious what the correct answer for #2 is. would you post it when you get it? from a practical viewpoint i think it should be formulated the way daytonite did it (with the addition of the % value) but in reality it wasn't, so mathematically my answer is correct, so i'm wondering if it's a typo on the test or if the school intended it that way. and good luck on your test! do you have to get 100% correct?

[Daytonite, BSN, RN]

Actually, once sodium chloride goes into solution it's proper form of concentration in the world of healthcare is referred to as "milli-equivalents" of sodium and chloride since the compound loses its identity and breaks down into it's component elements.