Accurately weigh (to 0.1 mg) about 0.1g of pure salicylic acid (weight by differ
ID: 474897 • Letter: A
Question
Accurately weigh (to 0.1 mg) about 0.1g of pure salicylic acid (weight by difference using a weighing bottle) and quantitatively transfer to a 100 ml volumetric flask. After thorough mixing dilute to the mark with a NaOH solution so that the final concentration is 0.1 M NaOH. Calculate the salicylic acid concentration (mg/L) in this Stock solution. Prepare five dilutions of your stock solution using 1,2,3,4, and 5 mls diluted to 100ml with 0.1 M NaOH. Calculate the salicylic acid concentration (mg/L) in your stock solution and each standard
Explanation / Answer
0.1g of pure salicylic acid is 100 mg
Calculate the salicylic acid concentration (mg/L) in this Stock solution.
Now the stock solution has 100 mg / 100 ml but we need answer in mg / L
We know that 1 ml = 10-3 L substuting above 100 mg / (100 X 10-3) L = 1000 mg/L = 1 g/L
Each ml of stock contains 1 mg of salicylic acid therefore 1,2,3,4 and 5 mls of stock solution diluted to 100 ml correspond to 1 mg/100 ml, 2 mg/100 ml, 3 mg/ 100 ml, 4 mg / 100 ml and 5 mg / 100 ml
so the concentration in mg/L is given as 10 mg/L, 20 mg/L, 30 mg/L, 40 mg/L and 50 mg/L