Photo AI
The percentage purity of powdered, impure magnesium sulfate, MgSO₄, can be determined by gravimetric analysis - VCE - SSCE Chemistry - Question 1 - 2008 - Paper 1
Question 1
The percentage purity of powdered, impure magnesium sulfate, MgSO₄, can be determined by gravimetric analysis. Shown below is the method used in one such analysis. ... show full transcript
Worked Solution & Example Answer:The percentage purity of powdered, impure magnesium sulfate, MgSO₄, can be determined by gravimetric analysis - VCE - SSCE Chemistry - Question 1 - 2008 - Paper 1
Step 1
Calculate the mass of BaSO₄ precipitate
Answer
To find the mass of barium sulfate (BaSO₄) formed, refer to the graph provided in the marking scheme that shows a leveling off at a specific volume of BaCl₂ added. Given that the maximum mass of BaSO₄ is 2.00 g, this tells us the limits of the precipitate formation.
Step 2
Identify the relationship with BaCl₂ concentrations
Answer
With 0.200 M BaCl₂, it is noted from the marking scheme that the volume necessary to reach the plateau in mass is half the volume used with 0.100 M. This signifies that concentration directly influences the amount required to achieve the same amount of precipitate.
Step 3
Calculate the percentage purity of the sample
Answer
The percentage purity of the sample can be calculated using the equation:
From the known mass of the sample (32.50 g) and the amount of BaSO₄ precipitated, we can calculate the mass of pure MgSO₄ from stoichiometry, then apply it to this formula to find the percentage purity.