February 26, 2024, 12:40:13 AM
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Topic: How do I calculate the uncertainty of varying concentrations of Sodium Thiosulfa  (Read 544 times)

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Offline RoronoaAoes

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I have the percentage uncertainty of a 0.15 M solution, but I don't know how to calculate the uncertainty for the 0.12, 0.09, 0.06 and 0.03 solutions, can someone help me?

Na2S2O3 Solution:
A 0.15 mol/dm3 solution of sodium thiosulfate was made by finding the mass amount of solid sodium thiosulfate needed to produce the solution using this formula
C = nv
C = Concentration (mol/L)
n = Mols
v = Volume (L)
0.15 = n1
n = 0.151
n = 0.15

Through this formula, it was found that 0.15 mols of sodium thiosulfate was needed. To find this amount in grams, this equation was used.
n = mMM
n = Mols
m = Mass (g)
MM = Molar mass (g/mol)
Molar mass of Sodium Thiosulfate, Na2S2O3 =(22.992) + (32.07 2) + (16.00 3)
= 158.12 g

0.15 = m158.12
m = 0.15158.12
m =23.718 g
23.718 g of sodium thiosulfate was measured on a scale then added to 1 L volumetric flask with water to make the 0.15 mol/L solution

1000 cm3 0.15 M  Sodium Thiosulfate solution;
%uncertainty mass = 0.0123.718100 = 0.04216%
%uncertainty volume = 0.51000100=  0.05%
Total uncertainty =0.04216 +0.05 = 0.09216% 

Offline mjc123

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Sort your formatting out!!! At present your statements are at best confusing, at worst plain wrong.
e.g. C = nv is wrong. It should be C = n/v.
Are the / and * keys not working on your keyboard?
When you say %uncertaintyvolume = 0.51000100, do you mean 0.5/1000*100? Write that!
Are you saying that the uncertainty in the mass is 0.01g, and the uncertainty in the volume is 0.5mL? Make that explicit in the method statement.
What's your problem calculating the uncertainty for the other solutions? Are they made in the same way? Calculate the uncertainty in the same way. Are they made by diluting the first solution? What's the procedure for that?

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