If 150 mg of aspirin are rinsed with three portions of 10 mL of water at 25 degrees Celsius, how much aspirin is recovered? Solubility of aspirin in water at 25 degrees Celsius is one gram of aspirin per 300 mL of water.
Solubility is 1g aspirin in 300 mL.
So how much aspirin is lost with a 10 mL rinse and I use the term rinse lightly which I will comment on later.
1000 mg aspirin x 10mL/300 mL = 33.33 for the first rinse.
33.33 for the second rinse.
33.33 for the third rinse.
Total is 100 mg aspirin lost or 150 mg initially - 100 mg lost = 50 mg recovered.
Note about the rinse. If you "rinse" something you don't give it time to equilibrate so the solubility data may be misleading; i.e., in a rinse you don't give the solvent time enough to form a saturated solution. Therefore, you really don't lose this much aspirin; however, from the way the problem is worded I think the author expects rinse to be used in the sense that it dissolves all of the aspirin possible.
To calculate how much aspirin is recovered, we need to determine the amount of aspirin that dissolves in the water and subtract it from the initial amount of aspirin.
Given:
- Amount of aspirin rinsed = 150 mg
- Each portion of water used = 10 mL
- Solubility of aspirin in water at 25 degrees Celsius = 1 g per 300 mL
First, let's convert the solubility limit to the same units as the amount of aspirin rinsed:
- 1 g per 300 mL is equivalent to 1000 mg per 300 mL
- Simplifying, it is approximately 3.33 mg per mL
Now, we can determine the amount of aspirin that dissolves in each portion of water:
- One portion of water is 10 mL, so the amount of aspirin that can dissolve in it is 3.33 mg/mL * 10 mL = 33.33 mg
Since we rinse the aspirin with three portions of water, the total amount of aspirin that dissolves is:
- 33.33 mg * 3 = 99.99 mg (rounded to 100 mg)
Finally, we can calculate the amount of aspirin recovered by subtracting the amount dissolved from the initial amount rinsed:
- Aspirin recovered = Amount rinsed - Amount dissolved
- Aspirin recovered = 150 mg - 100 mg = 50 mg
Therefore, 50 mg of aspirin is recovered after rinsing it with three portions of 10 mL of water at 25 degrees Celsius.