Gravimetric Analysis to calculate wgt%?

  • Thread starter Antonio8
  • Start date
  • Tags
    Analysis
In summary, a solid 0.5330-g sample containing only AgNO3 and Hg2(NO3)2 was dissolved in an aqueous medium, and the metal cations were precipitated as a mixture of the respective insoluble cobalticyanide salts. The precipitate was washed and dried, and its mass was found to be 0.5571 g. Using a gravimetric analysis method, the weight percent of AgNO3 in the original sample was attempted to be calculated, but the answer was incorrect. This may be due to the system of equations being ill-conditioned or dependent.
  • #1
Antonio8
2
0
A solid 0.5330-g sample which contains only AgNO3(s) and Hg2(NO3)2(s) is dissolved in aqueous medium and the metal cations are precipitated as a mixture of the respective insoluble cobalticyanide salts.
3Ag+(aq) + Co(CN)63−(aq) → Ag3[Co(CN)6](s)
3Hg22+(aq) + 2Co(CN)63−(aq) → (Hg2)3[Co(CN)6]2(s)
The washed and dried precipitate has mass 0.5571 g.
What was the wt% of AgNO3 in the original sample?I tried to solve this using (weight precipitate)*(gravimetric factor)(100) / weight of sample but i got the wrong answer!? can someone please shed some light on this for me !?
 
Physics news on Phys.org
  • #2
Antonio8 said:
I tried to solve this using (weight precipitate)*(gravimetric factor)

Which gravimetric factor? Your precipitate is a mixture of TWO solids.

The idea behind this type of the question is to write two independent equations - for example assume nAg (number of moles of Ag) and nHg2 are your unknowns. Express masses of the initial and final mixtures using these numbers of moles (and respective molar masses) and you have two equations in two unknowns - just solve.

But I have a feeling it won't work as expected in this case, as the system of equations is ill-conditioned (or perhaps they are even just dependent).
 

1. What is gravimetric analysis?

Gravimetric analysis is a quantitative method used in analytical chemistry to determine the amount or concentration of a substance in a sample. It involves the measurement of the mass of a substance or its component after a chemical reaction has taken place.

2. How does gravimetric analysis work?

In gravimetric analysis, a known amount of sample is subjected to a specific chemical reaction to form a precipitate. The precipitate is then filtered, dried, and weighed to determine its mass. This mass is then used to calculate the amount of the substance in the original sample.

3. What is the principle behind gravimetric analysis?

The principle behind gravimetric analysis is that the mass of a substance can be used to determine its amount or concentration. This is based on the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.

4. What is the formula for calculating weight percent using gravimetric analysis?

The formula for calculating weight percent using gravimetric analysis is: weight percent = (mass of substance/mass of sample) x 100%. This formula assumes that the substance being analyzed is the only component in the sample.

5. What are the factors that can affect the accuracy of gravimetric analysis?

The accuracy of gravimetric analysis can be affected by factors such as contamination of the sample, incomplete precipitation, and errors in measurement of the mass of the precipitate. It is important to carefully control these factors in order to obtain accurate results.

Similar threads

Percent yield crazy--help with calculations?
    • Biology and Chemistry Homework Help
Replies
2
Views
1K
Checking Answers of Chemistry Assignment
    • Biology and Chemistry Homework Help
Replies
2
Views
7K
A question about gravimetric analysis
    • Chemistry
Replies
2
Views
8K

Hot Threads

Recent Insights

Back
Top