You have titrated an oil sample and used 6.2 mL of 0.01 N sodium thiosulfate (Na2S2O3) solution to reach the endpoint for the oil sample blank. The weight of the oil sample is 2 gr... You have titrated an oil sample and used 6.2 mL of 0.01 N sodium thiosulfate (Na2S2O3) solution to reach the endpoint for the oil sample blank. The weight of the oil sample is 2 grams. Calculate the peroxide value (PV) of the oil sample in milliequivalents per kilogram (meq/kg). Read more

Steps to Solve

1. Calculate the Normality of the Thiosulfate Solution Used for Oil Sample

   The normality of the sodium thiosulfate used for the blank is $0.01 , N$, and the volume used for the blank is $1.2 , mL$. We can calculate the milliequivalents used for the blank:

   [ \text{Milliequivalents (meq)} = \text{Normality (N)} \times \text{Volume (mL)} = 0.01 , N \times 1.2 , mL = 0.012 , \text{meq} ]

2. Calculate the Total Milliequivalents from Titration of Oil Sample

   For the oil sample, the volume of thiosulfate used is $6.2 , mL$. Thus:

   [ \text{Milliequivalents for oil sample} = 0.01 , N \times 6.2 , mL = 0.062 , \text{meq} ]

3. Determine the Milliequivalents of Peroxides in the Oil Sample

   Subtract the milliequivalents from the blank from the total milliequivalents from the oil sample to find the peroxides:

   [ \text{Peroxides (meq)} = \text{Milliequivalents for oil sample} - \text{Milliequivalents for blank} = 0.062 , \text{meq} - 0.012 , \text{meq} = 0.05 , \text{meq} ]

4. Calculate the Peroxide Value (PV)

   Since the weight of the oil sample is $2 , g$, we need to convert it to kilograms. Therefore, the oil sample weighs $0.002 , kg$. To find the PV in milliequivalents per kilogram, we use:

   [ \text{PV} = \frac{\text{Peroxides (meq)}}{\text{Weight of oil sample (kg)}} = \frac{0.05 , \text{meq}}{0.002 , kg} = 25 , \text{meq/kg} ]