Concentration problem using absorbance

AI Thread Summary
The discussion revolves around a homework problem involving the calculation of phosphorus elimination based on urine analysis. A patient produced 1122 mL of urine in 24 hours, with a phosphate concentration of 2.5 ppm determined from absorbance measurements. The confusion arises from the distinction between phosphorus and phosphate, as the problem asks for both but uses phosphate standards for analysis. It is clarified that while phosphate contains phosphorus, they are not interchangeable terms in the context of the calculations. Understanding this distinction is crucial for accurately answering the questions posed in the homework.
Rujano
Messages
17
Reaction score
0

Homework Statement



Hi. A patient produced 1122 mL of urine in 24 hours.
A 1.00-mL aliquot of the sample was treated with
Mo(Vl) and ascorbic acid and was diluted to a
volume of 50.00 mL. A calibration curve was pre-
pared by treating 1.00-mL aliquots of phosphate
standard solutions in the same manner as the urine
sample. The absorbances of the standards and the
urine sample were obtained at 650 nm, and then
concentration of 1.00ml diluted aliquots of phosphate is found 2.5ppm.

What mass in grams of phosphorus was eliminated per day by the patient?

What is the concentration of phosphate in the urine (mmol/L)?

Homework Equations



A = abC

The Attempt at a Solution



Ok, what I really don't get is why in the first question they ask me for PHOSPHOROUS and in the second one for PHOSPHATE. And again, in the problem it says that this is a method used to determine PHOSPHOROUS, yet the standards are made of PHOSPHATE.

It's really confusing to me... they shouldn't be the same thing, right?
 
Physics news on Phys.org
Phosphate contains phosphorus - one atom per molecule.
 
Thread 'Confusion regarding a chemical kinetics problem'

Thread 'Confusion regarding a chemical kinetics problem'

TL;DR Summary: cannot find out error in solution proposed. [![question with rate laws][1]][1] Now the rate law for the reaction (i.e reaction rate) can be written as: $$ R= k[N_2O_5] $$ my main question is, WHAT is this reaction equal to? what I mean here is, whether $$k[N_2O_5]= -d[N_2O_5]/dt$$ or is it $$k[N_2O_5]= -1/2 \frac{d}{dt} [N_2O_5] $$ ? The latter seems to be more apt, as the reaction rate must be -1/2 (disappearance rate of N2O5), which adheres to the stoichiometry of the...
View full post »

Thread 'Prove that evolution is constant (Provide at least two arguments to support your position)'

I don't get how to argue it. i can prove: evolution is the ability to adapt, whether it's progression or regression from some point of view, so if evolution is not constant then animal generations couldn`t stay alive for a big amount of time because when climate is changing this generations die. but they dont. so evolution is constant. but its not an argument, right? how to fing arguments when i only prove it.. analytically, i guess it called that (this is indirectly related to biology, im...
View full post »

Similar threads

How to Analyze Palladium Content in a Meteorite Using Standard Addition?
Replies
2
Views
4K
What is the Concentration of Vitamin A in Serum Using HPLC?
Replies
1
Views
5K

Hot Threads

Recent Insights

Back
Top