An impure sample contains 0.95g of benzoic acid and 0.05 of salicylic acid. Solubilities in water of the two compounds are given in the following table.
Solubility at 20 degrees (g/10mL)
benzoic acid: 0.029
salicylic acid: 0.22
Solubility at 100 degrees (g/10mL)
benzoic acid: 0.680
salicylic acid: 6.67
what is the minimum volume of boiling water needed to dissolve the 1.0g sample?
The least soluble in benzoic acid and you have 0.95 g of it. Solubility is 0.680g benzoic acid/10 mL 100 degree water. We have 0.95 g sample.
10 mL x (0.95g/0.68g) = ? mL needed.
14.04ml
23 ml
To find the minimum volume of boiling water needed to dissolve the 1.0g sample, we need to determine the solubility of each compound in boiling water. Based on the given information, the solubilities at 100 degrees for benzoic acid and salicylic acid are 0.680 g/10mL and 6.67 g/10mL, respectively.
Since we have 1.0g of the sample, we can calculate the amount of each compound present in the sample:
Amount of benzoic acid = 0.95g
Amount of salicylic acid = 0.05g
Next, we need to determine how many milliliters (mL) of boiling water are required to dissolve the given amounts of each compound.
For benzoic acid:
Amount of benzoic acid (g) / Solubility of benzoic acid (g/10mL) = Volume of boiling water (mL)
0.95g / 0.680 g/10mL = 1.397 mL
For salicylic acid:
Amount of salicylic acid (g) / Solubility of salicylic acid (g/10mL) = Volume of boiling water (mL)
0.05g / 6.67 g/10mL = 0.007 mL
Since the solubility of salicylic acid is much higher than that of benzoic acid at 100 degrees, we can assume that the salicylic acid will completely dissolve in a negligible volume of boiling water.
Therefore, the minimum volume of boiling water needed to dissolve the 1.0g sample is approximately 1.397 mL.