iron standard solutions

Request or contribute your recipes here. You can also try doing a search, as there are some old recipe posts which have not or cannot be moved over to this forum.
Post Reply
User avatar
Kathryn
Posts: 389
Joined: 01 Jun 2006, 10:00
Job Title: Lab Technician
School: Cedars Christian College
Suburb: Farmborough Hts, Wollongong
State/Location: NSW

iron standard solutions

Post by Kathryn »

Hi
Hoping someone can help me out with making standard iron solutions. The chem students are going to be doing the Colorimetric analysis of iron in foods (Pearson) and need standard solutions of iron:
0.0050%
0.0025%
0.0013%
0.0010%
0.0005%

Why doesn't the textbook provide instructions on how to make these???
We did the experiment last year but I can not find the instructions and that teacher has recently moved on. It's definitely above my pay scale to figure this out!
Thanks in advance for your help. :unsure:
Kathryn
Merilyn1
Posts: 1476
Joined: 12 Mar 2013, 08:10
Job Title: Labbie
School: Wollondilly Anglican College
Suburb: Tahmoor
State/Location: NSW

Re: iron standard solutions

Post by Merilyn1 »

I think Pearsons provide on-line notes for the labbie. I've just never worked out how to access them!
Marama T
Posts: 214
Joined: 01 Aug 2017, 12:19
Job Title: Laboratory technician
School: College
State/Location: NSW

Re: iron standard solutions

Post by Marama T »

Hi Kathryn. I think you work this out as follows. I will assume the percentage is weight of solute/weight of solution. Start with your desired volume of solution. If you need 500mL of each, for example, each solution will weigh 500g. Then multiply the weight of the solution by the percentage required.
0.0050 x 500 = 2.5. In this case, add 2.5g of your iron compound to 497.5mL water.
I don't know which Pearson book to look in - it might help if I could read the prac.
Also, if the percentage is of iron alone then that complicates matters. Get back to me if you need help.
User avatar
Wayne
Posts: 305
Joined: 17 May 2006, 10:00
School: Mount Carmel College
Suburb: Sandy Bay
State/Location: TAS

Re: iron standard solutions

Post by Wayne »

0.0050% is 0.0050g made up to 100mL, so would be 0.025g for 500mL. I am fairly sure if you making standard solutions of iron the percentage will have to be of the iron not of, for example, iron chloride (or whatever other iron salt you are using).
Marama T
Posts: 214
Joined: 01 Aug 2017, 12:19
Job Title: Laboratory technician
School: College
State/Location: NSW

Re: iron standard solutions

Post by Marama T »

Oh yes! My mistake. It should be 0.0050 x 5, not 500. Thank you, Wayne. That'll teach me for doing calculations first thing in the morning.
User avatar
Kathryn
Posts: 389
Joined: 01 Jun 2006, 10:00
Job Title: Lab Technician
School: Cedars Christian College
Suburb: Farmborough Hts, Wollongong
State/Location: NSW

Re: iron standard solutions

Post by Kathryn »

Managed to find the calculations from last year - it is more complicated than just weighing out a percentage as they have to be made from combining potassium thiocyanate and iron nitrate. If anyone is interested I will put up what I am doing.
doconnor
Posts: 3
Joined: 31 May 2007, 09:54
State/Location: NSW

Re: iron standard solutions

Post by doconnor »

this is what we did last year
make up a fresh solution of FeCl3 (iron 111 chloride) 5%
0.5g 10ml H2O This is solution A
1ml solution A in 999ml H20 = 0.005% = solution B
then dilute solution B
0.0025% 50/50
0.0013% 25/75
0.0010% 20/80
0.0005% 10/90
hope this makes sense
Delma
Post Reply