wrong answers on 120 sdn calculation questions

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pharmer7

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I just started working on sdn 120 calculations and i'm stuck on number 49. I keep getting 2040 Osmols as the answer but the answer provided here says the answer is 20.4 mOsmols. Looks like i'm off by a few decimal points "if" the answer is correct. Am I off or is the answer provided here wrong? Please help.

I've also heard that there are few questions towards the end of the sheet where the answers are wrong. Can anyone please tell me what numbers they are and correct answers for those if anyone has done them? Thanks

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Hi... I went to check question 49 for you. Actually, the answer to this question is correct. Let me walk you through how I did it.

CaCl2 - 2 (H2O) has Mwt of 147

1 mOs= (Mwt/ electrical pts) / 1000 The number of elect parts= 3 ( 1 Calcium & 2 Chlorides)

So 1 mOs= (147/3)/1000= 0.049 gms therefore 1 mOs has 0.049gms

The concentration given is 10% so every 100 mls has 10g of CaCl2 - 2(H2O)

But the vials have 10mls... So use scissors...

10g ------in------ 100ml
so we have xg ------in------ 10ml

x will be equal to 1g of CaCl2 in 10ml vial

if 1mOsm has 0.049 g then how many mOsm will be in 1 g??? Scissors again...

1 mOsm-------in-------- 0.049g
y mOsm-------in-------- 1g

The final answer y= 20.41 mOsm


I hope that was helpful :) Let me know what other questions u need and I'll help u through them :)
 
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wow, thanks. appreciate it.

I'll take a look at it again and i'll let u know if there's any confusions.

Also did u spot any wrong answers when u were doing this? if so what nubmers are they and wat are the corresponding correct answers?
 
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I don't blame you on that one for question 12... the question was absolutely not clear because it appeared that they want the dextrose to be 10% of the total volume... but according to the answer, they wanted to know how much 10% they needed to add, so by alligation you can figure it out ...
 
Ok, question#91 is wrong answer. The right answer should be 511.5 milliosmoles.
Yes... you're right.. the answer they gave is wrong. They used only the amount provided to the patient and not the total amount of KCl in the IV bag... good catch...
 
anyone know how to solve this calculation? moora? or anyone?

The total energy expenditure (TEE) for a patient is 2,645 kcal/day. The patient is receiving 1,526 kcal from dextrose and 890 kcal from protein. How many kcal should be provided by the lipids?

A. 229 kcal
B. 1,755 kcal
C. 560 kcal
D. 1,017 kcal
E. 1,119 kca

also on the naplex, do we have to type in units? i was told that sometimes the answer had to be typed in. do we include units as well? or just the numerical value?
 
anyone know how to solve this calculation? moora? or anyone?

The total energy expenditure (TEE) for a patient is 2,645 kcal/day. The patient is receiving 1,526 kcal from dextrose and 890 kcal from protein. How many kcal should be provided by the lipids?

A. 229 kcal
B. 1,755 kcal
C. 560 kcal
D. 1,017 kcal
E. 1,119 kca

also on the naplex, do we have to type in units? i was told that sometimes the answer had to be typed in. do we include units as well? or just the numerical value?
The answer is E...

TEE - Dextrose = Calories left to be matched by lipids
2645- 1526= 1119 KCal

The reason why we do not subtract proteins is that proteins are not looked at as an energy source. It is reserved for muscle building rather than for energy requirement...

For the NAPLEX I don't think it would hurt to put in the units... Just watch out for what units they require you to answer in :)
 
ooooh yessss now it rings a bell! that's right! protein is not considered as one of carbs like lipids and dextrose are! ugh, such an easy question. alright.. now i'm beginning to worry for myself. lol. THANKS MOORA!:thumbup::thumbup::thumbup:

I guess you've already taken ur NAPLEX? u must've done very well. If you don't mind asking, what was your naplex score? What state are you from? lol, i'm becoming nosy

so back to my questions, on the test we don't have to include units? it's optional?
 
ooooh yessss now it rings a bell! that's right! protein is not considered as one of carbs like lipids and dextrose are! ugh, such an easy question. alright.. now i'm beginning to worry for myself. lol. THANKS MOORA!:thumbup::thumbup::thumbup:

I guess you've already taken ur NAPLEX? u must've done very well. If you don't mind asking, what was your naplex score? What state are you from? lol, i'm becoming nosy

so back to my questions, on the test we don't have to include units? it's optional?
No, I didn't take my naplex yet. I'm taking it beginning of next month in CA...

I'm starting to panic... I have 3 weeks left and didn't even get started on ONCO, HIV, Infectious diseases & Rheumatoid Arthiritis :S

Big topics and lots of meds... We're in the same boat lol Thanks for the compliment though... I need it because I'm very edgy now :\

Oh and about your questions... I'm as new as you, but I still think it won't hurt to include units in your answer...
 
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you'll do fine! and 3 weeks is more than enough time to cover those main topics, i think. Looks like you have the calculation part down. I wouldn't be too worried if I were you.

I'm taking mine in 3 days. getting anxious!
 
Oh goodness gracious... Good luck and please let me know how your test was! I'm dying here lol
 
yap, well i got 509.48 mOsmol on #91 but close enough. the answer was off on the explanation sheet cuz they used KCL that was provided to the patient instead of original amount in the bag, correct? thanks
 
yap, well i got 509.48 mOsmol on #91 but close enough. the answer was off on the explanation sheet cuz they used KCL that was provided to the patient instead of original amount in the bag, correct? thanks
Yea, that's what they did wrong... Good luck :)
 
I think there are more mistake in the 120 questions... Please, feel free to correct me if I'm wrong because I'd like to learn the right answer then...

Question 69... There is NO way that the answer they gave is right...

Why did he multiply 9mOsm to 3?!!!!! They want 9 in the final TPN... not 27!!! That's first... Here's my work out...

Mwt of Na3PO4= 3(23)+ 31+4(16)= 164 and we have 3 electrical Na parts so...

So 1 mOsm of Na2PO4= 164/3 * 1/1000= 0.0546 gm

So to have 9 mOsm= 9 * 0.0546= 0.491gm

Melliquiv we divide my valence sooo...

1meq= 164/1 * 1/1000= 0.164gm

By criss-cross....

1 meq ------ has----- 0.1694gm
so x meq--------has--------- 0.491gm

x= 2.89 meq ~ 3meq!!!!
 
I think there are more mistake in the 120 questions... Please, feel free to correct me if I'm wrong because I'd like to learn the right answer then...

Question 69... There is NO way that the answer they gave is right...

Why did he multiply 9mOsm to 3?!!!!! They want 9 in the final TPN... not 27!!! That's first... Here's my work out...

Mwt of Na3PO4= 3(23)+ 31+4(16)= 164 and we have 3 electrical Na parts so...

So 1 mOsm of Na2PO4= 164/3 * 1/1000= 0.0546 gm

So to have 9 mOsm= 9 * 0.0546= 0.491gm

Melliquiv we divide my valence sooo...

1meq= 164/1 * 1/1000= 0.164gm

By criss-cross....

1 meq ------ has----- 0.1694gm
so x meq--------has--------- 0.491gm

x= 2.89 meq ~ 3meq!!!!

yea i remember that question. I didn't understand why they would multiply 3 to 9. it didn't make sense to me. i thought the explanation was weird. i just let that be and found a similar question and moved on
 
I think there are more mistake in the 120 questions... Please, feel free to correct me if I'm wrong because I'd like to learn the right answer then...

Question 69... There is NO way that the answer they gave is right...

Why did he multiply 9mOsm to 3?!!!!! They want 9 in the final TPN... not 27!!! That's first... Here's my work out...

Mwt of Na3PO4= 3(23)+ 31+4(16)= 164 and we have 3 electrical Na parts so...

So 1 mOsm of Na2PO4= 164/3 * 1/1000= 0.0546 gm

So to have 9 mOsm= 9 * 0.0546= 0.491gm

Melliquiv we divide my valence sooo...

1meq= 164/1 * 1/1000= 0.164gm

By criss-cross....

1 meq ------ has----- 0.1694gm
so x meq--------has--------- 0.491gm

x= 2.89 meq ~ 3meq!!!!

They want the result in mEq not mMole, so if you do the calculations 9 mMole = 27 mEq
 
They want the result in mEq not mMole, so if you do the calculations 9 mMole = 27 mEq
I did reply in mEq... look at the end of the answer...
How did you get 9 mOsm =27 meq?!

1mOsm= 0.0546gm so
9 mOsm= 0.491gm...
and 1 meq= 0.164gm

so if you do the work out u'll get 3... 27 is impossible...

Show me ur work out,if you please, but not the one written in the answers of the 120 STD questions...
 
Yes true if we consider whole bag than I got 511.62 in question 91.But the question says IV fluid being administered ,so if we consider fluid that administered over 15 hours....which means 720ml then answer will be 368.37.
 
I thought the unit of MW is gram/mole or gram not mg. So that 74g (MW) of lithium carbonate = 2milimoles of lithium

74000mg of Lithcarbonate= 2mMoles of lithium
900mg of lithiumcarbonate= 900mg X 2mMoles / 74000

ANS: 164.4mMoles of lithiumcarbonate per day
 
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Molecular weight of lithium carbonate is 74.
you are right mole is in gram but millimole is mol wt in mg or mol wt (g)/1000
300x3 = 900mg dose
millimole of lithium = 900x2/74 = 24.3mMol
 
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If that is the case can somebody please explain to me what I did wrong in my work out????

Plus... in the question they want 9mOsm in the final preparation bag and not 27 (9 * 3mOsm)!!!

If you don't understand what I mean just please point out my mistake in the workout ...
 
Convert the milli moles to mg first and use the formula Meq = mg x valence/mol wt.or do it the way it is explained above.
 
Convert the milli moles to mg first and use the formula Meq = mg x valence/mol wt.or do it the way it is explained above.
you know Shahis?! I'm realllly good in maths... and so far I finished solving almost all the 120 questions correctly! That was the only one I can't still figure out!!!!!! And that's why sometimes I just hate maths!!!! Because of questions like these :D

Thankyou so much for your effort to help me out... I guess I'll just let that question be lol I think I'm missing something.... But I really do appreciate your help. And thanks to 3boooda too :)

Best of luck to you guys...
 
you know Shahis?! I'm realllly good in maths... and so far I finished solving almost all the 120 questions correctly! That was the only one I can't still figure out!!!!!! And that's why sometimes I just hate maths!!!! Because of questions like these :D

Thankyou so much for your effort to help me out... I guess I'll just let that question be lol I think I'm missing something.... But I really do appreciate your help. And thanks to 3boooda too :)

Best of luck to you guys...
No problem. and that's all about math. Crazy stuff .-))
 
Good luck to you all....keep posting new questions and queries till we all pass the boards..
 
Can anyone help me with #57 in the 120 SDN? I don't understand why you would multiply 50% x 1.40 = 70% w/v? And I also don't remember how to calculate mEq , millimoles, & mOsm ? Like #82, 83, & 84. Please help! Thank you
 
Anymore input on which questions are wrong? Thought this thread needed a bump up because this is really important for those that are studying to know which wrong answers to look out for.
 
I did reply in mEq... look at the end of the answer...
How did you get 9 mOsm =27 meq?!

1mOsm= 0.0546gm so
9 mOsm= 0.491gm...
and 1 meq= 0.164gm

so if you do the work out u'll get 3... 27 is impossible...

Show me ur work out,if you please, but not the one written in the answers of the 120 STD questions...


My friend, you asked for a FULL AND DETAILED workout, so here it is, please be patient because I will write with lots of details:

++++++++++++++++++++++++++

PROFESSOR WROTE:

MW of Na phosphate = 164

How do we get above?

Knowledge: Na phosphate = Sodium Phosphate = Na + Na + Na + P + O + O + O + O = Na3PO4

GIVEN: Na = 23, P = 31, O = 16

Combined, we get: 23 + 23 + 23 + 31 + 16 +16 +16 +16 = 164

This means:

1 MOLE of Sodium Phosphate = 164 grams of Sodium Phosphate

This also means:

1 miliMOLE of Sodium Phosphate = 164 miligrams of Sodium Phosphate

This DOES NOT mean:

1 OS-MOLE of Sodium Phosphate = 164 grams of Sodium Phosphate

This DOES NOT mean:

1 miliOS-MOLE of Sodium Phosphate = 164 miligrams of Sodium Phosphate

With that in mind, let's continue:

++++++++++++++++++++++++++

PROFESSOR WROTE:

So, 164 mg = 3 millimoles of Na per millimole Na phosphate

How do we get above?

Knowledge: Na phosphate = Sodium Phosphate = Na + Na + Na + P + O + O + O + O = Na3PO4

That means:

1 MOLE of Na phosphate = 3 MOLES of Na

We found out earlier: 1 MOLE of Na phosphate = 164 grams of Na phosphate

Combined, we get:

1 MOLE of Na phosphate = 3 MOLES of Na = 164 grams of Sodium Phosphate

This also means:

1 mili-MOLE of Na phosphate = 3 mili-MOLES of Na = 164 mili-grams of Sodium Phosphate

With that in mind, let's continue:

++++++++++++++++++++++++++

PROFESSOR WROTE:

9 mMoles of Na phosphate (x) 3 = 27 mMoles of sodium

How do we get above?

GIVEN: WE WILL ADD INTO BAG: 9 mMoles of Na phosphate.

We found out earlier: 1 mili-MOLE of Na phosphate = 3 mili-MOLES of Na

Combined, we setup CROSS MULTIPLY like this:

WE KNOW: 1 mili-MOLE of Na phosphate = 3 mili-MOLES of Na

WE WANT TO KNOW: 9 mili-MOLES of Na phosphate = X mili-MOLES of Na?

TOOL: CROSS MULTIPLY, we get:

[(9 mili-MOLES of Na phosphate) MULTIPLY (3 mili-MOLES of Na)] THEN DIVIDE OVER (1 mili-MOLE of Na phosphate) = 27 mili-MOLES of Na

So, we know now:

9 mili-MOLES of Na phosphate = 27 mili-MOLES of Na

With that in mind, let's continue:

++++++++++++++++++++++++++

PROFESSOR WROTE:

1 mMole of Na = 1 mEq of Na because Na is monovalent

How do we get above?

Here is my formula, I memorized this for exam (Valence means Charge means +):

If 1 charge, then, 1 Eq= 1 MOLE.
If 2 charge, then, 2 Eq= 1 MOLE.
If 3 charge, then, 3 Eq= 1 MOLE.
+++++++
Side note: Is that hard to remember? What is my trick?
Eq can be thought creatively as Excellent Queen.
MOLE can be thought creatively as Muscular John
If Muscular John has only 1 Power Charge, Muscular John will have only 1 Excellent Queen.
If Muscular John has only 2 Power Charge, Muscular John will have only 2 Excellent Queens.
If Muscular John has only 3 Power Charge, Muscular John will have only 3 Excellent Queens.
Now, to remember even better, we can substitute that P Charge as symbol, remember symbol of charge is a symbol like this +

If Muscular John has only 1 +, Muscular John will have only 1 Excellent Queen.
If Muscular John has only 2 +, Muscular John will have only 2 Excellent Queen.
If Muscular John has only 3 +, Muscular John will have only 3 Excellent Queen.
NOW USE YOUR CREATIVE MIND, PICTURE a JOHN, with 3 +++, and YOU WILL NEVER FORGET THIS HORRIBLE JOHN.
(I am not going to draw out the picture, you have to imagine the picture.)
(I was explained like this and given the picture of this in college and the picture stuck with me to solve this Eq problem.)

Let's continue......
that also means:

If 1 charge, then, 1 mili-Eq= 1 mili-MOLE.
If 2 charge, then, 2 mili-Eq= 1 mili-MOLE.
If 3 charge, then, 3 mili-Eq= 1 mili-MOLE.

Therefore, automatically, we HAVE TO KNOW THIS AUTOMATICALLY:

because Na is monovalent,
1 mMole of Na = 1 mEq of Na

With that in mind, let's continue:
++++++++++++++++++++++++++

PROFESSOR WROTE:

Thus, 27 mMoles = 27 mEq of sodium added with the Na phosphate

How do we get above?

We found earlier:

9 mili-MOLE of Na phosphate = 27 mili-MOLES of Na

We know in our head: If 1 charge, then, 1 mili-Eq= 1 mili-MOLE.

Combined, we set up CROSS MULTIPLY like this:

WE KNOW: 1 mili-Eq of Na = 1 mili-MOLE of Na.

WE WANT TO KNOW: X mili-Eq of Na = 27 mili-MOLES of Na?

TOOL: CROSS MULTIPLY, we get:

X mili-Eq of Na = [(1 mili-Eq of Na) MULTIPLY (27 mili-MOLES of Na)] THEN DIVIDE OVER (1 mili-MOLE of Na)

X mili-Eq of Na = 27 mili-Eq of Na

Answer: 27 mili-Eq of Na


Meaning:

Question was:

How many mEq’s of sodium will be added as a result of using sodium phosphate?

Answer is: When we use 9 mMol of Sodium Phosphate, we will add 27 mili-Eq of Na.

Answer is: When we use 9 mMol of Sodium Phosphate, we will add 27 mili-Eq of Sodium.

Conclusion: 3 posters here agreed: in Packet 120 math question from SDN, the answer of question 69 was correct at 27 mili-Eq of Sodium.
(Posters: 3booda, Shahis77,molyhelp)

Good luck. And please help others. Thank you very much in advance.
[email protected]
 
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I think there are more mistake in the 120 questions... Please, feel free to correct me if I'm wrong because I'd like to learn the right answer then...

Question 69... There is NO way that the answer they gave is right...

Why did he multiply 9 mOsm to 3?!!!!! They want 9 in the final TPN... not 27!!! That's first... Here's my work out...

Mwt of Na3PO4= 3(23)+ 31+4(16)= 164 and we have 3 electrical Na parts so...

So 1 mOsm of Na3PO4= 164/3 * 1/1000= 0.0546 gm

So 1 mOsm of Na3PO4= 164/4 * 1/1000 = 0.041 gm


My dear friend, sorry, you asked us to clarify where the key was in your work out, so, here I gently, friendly explain:
Question gave us and I quote:
Sodium Phosphate 9 mMol

You wrote and I quote:
So to have 9 mOsm= 9 * 0.0546= 0.491gm

Here is the key: The question asked us to add 9 mMol, not 9mOsm

Let's work together as a team here. I like your approach to convert everything into gram.
If you want to convert everything into gram and then find the answer, then, let's do by gram:

(LINE :) 1 Mol of Sodium Phosphate = 164 grams of Sodium Phosphate (Calculated, confirmed).
(LINE 2:) 1 mMol of Sodium Phosphate = 164 mgrams of Sodium Phosphate (Converted Mol to mMol, gram to mgram))
(LINE 3:) 9 mMol of Sodium Phosphate = 1476 mgrams of Sodium Phosphate (question asked to use 9 mMol, Line 2 multiplied by 9 on both sides)

(LINE 4:) 1 Mol of Sodium Phosphate = 3 mol of Sodium Alone (Na3Po4 = 3 Na = 3 Sodium).
(LINE 5:) 1 mMol of Sodium Phosphate = 3 mmol of Sodium Alone. (Line 4 converted to mMol)
(LINE 6:) 9 mMol of Sodium Phosphate = 27 mmol of Sodium Alone. (Line 5 multiplied by 9 (question asked: 9 mMol))

(LINE 7:) 27 mmol of Sodium Alone = 1476 mgrams of Sodium Phosphate (Combined Line 3 and 6)
(LINE 8:) 27 mEq of Sodium Alone = 1476 mgrams of Sodium Phosphate (Converted mMol to mEq, Sodium is 1 charge, Automatically: 1 mmol = 1 mEq, (memorized))

(LINE 9 = Answer) 27 mEq of Sodium Alone = 9 mMol of Sodium Phosphate (Combined line 8 and 3)
Answer in word, when we add 9 mMol of Sodium Phosphate, we are adding 27 mEq of Sodium Alone.

(Sorry for repeating a few lines, I wanted to be clear for you.)

Guide:
MOLE of WHOLE = GRAM of WHOLE
MOLE of WHOLE = OSMOL of WHOLE
MOLE of WHOLE= MOL of ION
MOL of ION = Eq of ION


MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: GRAM of Sodium Phosphate
MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: OSMOL of Sodium Phosphate
MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: MOLE of Sodium Alone

1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 164 GRAM of Sodium Phosphate
1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 4 OSMOL of Sodium Phosphate
1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 3 MOLE of Sodium Alone

1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 3 MOLE of Sodium Alone
9 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 27 MOLE of Sodium Alone
9 mili-MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 27 mili-MOLE of Sodium Alone

1 MOLE of Sodium Alone CAN BE CONVERTED TO BE: 1 EQ of Sodium Alone
27 MOLE of Sodium Alone CAN BE CONVERTED TO BE: 27 EQ of Sodium Alone
27 mili-MOLE of Sodium Alone CAN BE CONVERTED TO BE: 27 mili-EQ of Sodium Alone

Answer in word, when we add 9 mMol of Sodium Phosphate, we are adding 27 mEq of Sodium Alone.

I hope that helped some friends out there.
Good luck and please help others. Thank you very much in advance.
 
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To future exam candidate: Quick Test to yourself and hopefully, I can help you avoid fatal mistake:
What is 1 grain?
1 grain is 60 grams or milligrams or grams or milligrams or grams or milligrams?
Confused?
Try this trick from a nursing math book:
Think of 1 grain is like a clock at 1 hr.
1 grain is like 1 gr is like 1 hr is like 60 minutes is like 60 milli-grams. For sure. See the mi of minute matching the mi of milligrams? For sure, 1 gr is 60 milligrams, not 60 grams
(Or 65 milligrams, or 64.8 milligrams, depending on you want to use.
In packet, answer of question 38 explained like this:
NOTE: Hyoscine HBr is a potent alkaloid and, as such, the grain to mg equivalent is reduced to
60 mg per grain to provide a safety factor when administering the drug. This same concept is the
usual reason for drug products where 60 mg = 1 grain. Again, with NAPLEX being multiple choice,
you can get the answer they want. NAPLEX would likely set up the answer to be based on the 64.8
mg grain.)

The point is: 1 gr is about 60 milligrams, not grams.)
Proof? Reference? See picture below this line (from Google).

Good luck and please help others. Thank you very much in advance.
 

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Can anyone help me with #57 in the 120 SDN? I don't understand why you would multiply 50% x 1.40 = 70% w/v? And I also don't remember how to calculate mEq , millimoles, & mOsm ? Like #82, 83, & 84. Please help! Thank you



My friends, let me help you carefully and slowly so you can fly later during exam time:

Question 57. Dimethyl Sulfoxide Liquid is supplied as a 50% weight / weight solution with a specific gravity of 1.40. What is the percent weight / volume of liquid dimethyl sulfoxide?

FULL Answer of 57 was:
50% wt/wt (x) 1.40 Sp Gr = 70% wt/vol


For question 57, the detailed explanation is:

To simplify the writing, the STUFF we talk about today is Dimethyl Sulfoxide Liquid

STUFF = Dimethyl Sulfoxide Liquid

MIXED SOLUTION = Dimethyl Sulfoxide Liquid MIXED with Diluent


In the end, we want answer to have percent in WEIGH / VOLUME

In the end, we want answer to have grams of STUFF in 100 ml MIXED SOLUTION


Given specific gravity of mixed solution = 1.788

We know: if we measure 1 ml MIXED in lab, and weigh, we will have 1.788 grams of MIXED SOLUTION

1 ml of MIXED = 1.788 grams OF MIXED

Multiply 100 at both sides

WE GET:

100 ml of MIXED = 178.8 grams of MIXED

Flip both sides, we have the same:

178.8 grams of MIXED = 100 ml of MIXED


Given fact that this mixed solution also is 90% weight / weight

We know: if we make 100 grams of MIXED in lab, we will use 90 grams of REAL STUFF

100 grams of MIXED = 90 grams OF STUFF

WE KNOW: 100 grams of MIXED = 90 grams OF STUFF

WE WONDER: 178.8 grams of MIXED = X grams OF STUFF

Setup math:

100 grams of MIXED = 90 grams OF STUFF

178.8 grams of MIXED = X grams of STUFF

TOOL: CROSS MULTIPLY

[(178.8 grams of MIXED)MULTIPLY (90 grams OF STUFF)] THEN DIVIDE OVER (100 grams OF MIXED)

WE GET: X = 178.8 * 90 / 100 = 160.92 grams of STUFF

Meaning: In word, we have:

178.8 grams of MIXED = 160.92 grams of STUFF


We know now: 178.8 grams of MIXED = 160.92 grams of STUFF

We knew earlier: 178.8 grams of MIXED = 100 ml of MIXED


Combined, we get:

160.92 grams of STUFF = 100 ml of MIXED

We then can legally announce the name of this Mixed Solution as:

160.92 % MIXED SOLUTION (WEIGHT / VOLUME)

ANSWER: 160.92%


ANOTHER WAY
But, I spent 20 minutes to ALIGN this below MATH writing, somehow, I see I lose lots of spaces so items are group together even though I went back and forth to space them out:

(90 grams of STUFF)
-------------------------
(100 grams of MIXED)


MULTIPLY WITH
(1.788 grams of MIXED)
------------------------------
(1 ml of MIXED)



MULTIPLY WITH
(100)
-----
(100)





(90 grams of STUFF) (1.788 grams of MIXED) (100)
----------------- * -------------------- * ---------

(100 grams of MIXED) (1 ml of MIXED) (100)





We get
160.92 grams of STUFF
= --------------------- -------------------
100 ml of MIXED

Therefore, we then can legally announce the name of this Mixed Solution as:
160.92 % MIXED SOLUTION (WEIGHT / VOLUME)
ANSWER: 160.92%

That explained why professor wrote:
FULL Answer of 57 was:
50% wt/wt (x) 1.40 Sp Gr = 70% wt/vol

Professor was using an official formula from math book to convert between w/w and w/v

(Percent in weight/weight) MULTIPLY (Specific Gravity) = (Percent in weight/volume).
I just MULTIPLIED the left with (100/100)

(Percent in weight/weight) MULTIPLY (Specific Gravity) MULTIPLY (100/100) = (Percent in weight/volume).





I hope that I helped you pass this exam.

Good luck and please help others. Thank you very much in advance.
 
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hi can anyone help me understand question no. 30 ? I didn't get how it is 1000ml/20.4 parts ? I thought it is 1000 ml / 22.5 parts
 
If you solve by allegation method,
3%-0.9% = 2.1 parts of 23.4%
23.4% - 3% = 20.4 parts of 1000 ml.(0.9%)

If 20.4 parts are present in 1000ml
2.1 parts are present in how many mls?
Answer: 102.9 ml is added to 1000 ml
 
Hi there! I'm having a lot of difficulty with figuring out when to do allegation or use a ratio - such as the problems on the SDN 120 like #12 and, #30, #78. For example #12 I solved it setting up proportional ratios - I set up like:
1) I need 10% which is 10g/100mL = x/1000mL (total IV is 1L)
X= 100g needed
2) if I need 100g, how many mLs of the 70% dextrose will I need so:
70g/100mL = 100g/x
X = 142.9mL needed
--- this is way off from the answer key as they used allegation. However I'm SO confused as to when to set up direct ratios like I did above and when I need allegation. Please help if you can my exam is in 4 days and I'm borderline panic attack :(

My dear friend, sorry, you asked us to clarify where the key was in your work out, so, here I gently, friendly explain:
Question gave us and I quote:
Sodium Phosphate 9 mMol

You wrote and I quote:
So to have 9 mOsm= 9 * 0.0546= 0.491gm

Here is the key: The question asked us to add 9 mMol, not 9mOsm

Let's work together as a team here. I like your approach to convert everything into gram.
If you want to convert everything into gram and then find the answer, then, let's do by gram:

(LINE :) 1 Mol of Sodium Phosphate = 164 grams of Sodium Phosphate (Calculated, confirmed).
(LINE 2:) 1 mMol of Sodium Phosphate = 164 mgrams of Sodium Phosphate (Converted Mol to mMol, gram to mgram))
(LINE 3:) 9 mMol of Sodium Phosphate = 1476 mgrams of Sodium Phosphate (question asked to use 9 mMol, Line 2 multiplied by 9 on both sides)

(LINE 4:) 1 Mol of Sodium Phosphate = 3 mol of Sodium Alone (Na3Po4 = 3 Na = 3 Sodium).
(LINE 5:) 1 mMol of Sodium Phosphate = 3 mmol of Sodium Alone. (Line 4 converted to mMol)
(LINE 6:) 9 mMol of Sodium Phosphate = 27 mmol of Sodium Alone. (Line 5 multiplied by 9 (question asked: 9 mMol))

(LINE 7:) 27 mmol of Sodium Alone = 1476 mgrams of Sodium Phosphate (Combined Line 3 and 6)
(LINE 8:) 27 mEq of Sodium Alone = 1476 mgrams of Sodium Phosphate (Converted mMol to mEq, Sodium is 1 charge, Automatically: 1 mmol = 1 mEq, (memorized))

(LINE 9 = Answer) 27 mEq of Sodium Alone = 9 mMol of Sodium Phosphate (Combined line 8 and 3)
Answer in word, when we add 9 mMol of Sodium Phosphate, we are adding 27 mEq of Sodium Alone.

(Sorry for repeating a few lines, I wanted to be clear for you.)

Guide:
MOLE of WHOLE = GRAM of WHOLE
MOLE of WHOLE = OSMOL of WHOLE
MOLE of WHOLE= MOL of ION
MOL of ION = Eq of ION


MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: GRAM of Sodium Phosphate
MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: OSMOL of Sodium Phosphate
MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: MOLE of Sodium Alone

1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 164 GRAM of Sodium Phosphate
1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 4 OSMOL of Sodium Phosphate
1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 3 MOLE of Sodium Alone

1 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 3 MOLE of Sodium Alone
9 MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 27 MOLE of Sodium Alone
9 mili-MOLE of Sodium Phosphate CAN BE CONVERTED TO BE: 27 mili-MOLE of Sodium Alone

1 MOLE of Sodium Alone CAN BE CONVERTED TO BE: 1 EQ of Sodium Alone
27 MOLE of Sodium Alone CAN BE CONVERTED TO BE: 27 EQ of Sodium Alone
27 mili-MOLE of Sodium Alone CAN BE CONVERTED TO BE: 27 mili-EQ of Sodium Alone

Answer in word, when as add 9 mMol of Sodium Phosphate, we are adding 27 mEq of Sodium Alone.

I hope that helped some friends out there.
Good luck and please help others. Thank you very much in advance.
 
When the question asks you to prepare X% of solution by using two different solutions with Y% and Z%, you will have to solve the problem by allegation method!
 
How did they solve for 4.14 mL on question 33, I solved it by allegation method and another method and got 4 mL.
 
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