G. Determination of the Concentration of the Solution Prepared from Commercial A
ID: 1022785 • Letter: G
Question
G. Determination of the Concentration of the Solution Prepared from Commercial Aspirin or generic brand
1. The absorbance of diluted solution prepared for ASA Tablet was 0.1170. 2.
From the graph plotted in F, such an absorbance corresponds to a concentration of 7.984x10-5 mol/L ASA
H. Determination of the Percentage of Acetylsalicylic Acid in an Aspirin or generic brand Tablet (Tablet = 0.41g)
1. From G, the concentration of tetraaquasalicylatoiron(III) in the dilute solution was ?
2. The concentration of the dianion of salicylic acid in the 100 mL sodium hydroxide stock solution was ?
3. The number of moles of the dianion of salicylic acid in the 100 mL sodium hydroxide stock solution was ?
4. The number of moles of acetylsalicylic acid initially present and therefore also in the Aspirin tablet was ?
Explanation / Answer
The percentage of ASA in aspirin tablet can be determined using the graph. Here Y is the absorbance which is 0.1170, the m= 1663 and y-intercept= 0.01579
The formulae for calculating the concentration of ASA is Y=1663.X + 0.01579
X= [(0.1170-0.01579)/1663 ] = 6.08 *10-5 concentration of ASA
concentration of ASA in 0.41g of Aspirin= 0.41/180.57 =2.27* 10-3
% of ASA in Aspirin= 6.08 *10-5/ 2.27* 10-3 =2.67%
2)The complex is formed by the addition of NaOH and it forms salicylate dianion. The addition of acidified iron (III) ion produces the violet tetraaquosalicylatroiron (III) complex. So the concentration of tetraaquosalicylatroiron (III) complex is 7.984x10-5 mol/L
3) the concentration of dianion of salicylic acid in 100ml NaOH solution is 7.984x 10-5 mol/L x 0.100L =7.984x 10-4 /0.012L = 6.653x 10-3 mol/L-1
4) number of moles of dianion of salicylic acid in 100ml sodium hydroxide solution 6.653 x10-3mol/L-1 x 0.100l
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