What is the osmolarity of a 3.3%(w/v) Na₃PO₄ solution? A) 0.20 osmolar B) 0.40 osmolar C) 0.80 osmolar D) 1.6 osmolar

Question

Quizplus · Accepted Answer

To calculate osmolarity, we need to first find the molarity of the solution. To do this, we can assume 100g of the solution (since it's a percent by weight/volume), which would give us 3.3g of Na₃PO₄. We can then divide this by the molecular weight of Na₃PO₄ (142.04 g/mol) to get 0.0232 moles of Na₃PO₄. To find the osmolarity, we need to multiply the molarity by the number of particles the molecule dissociates into. Na₃PO₄ dissociates into 2 ions (Na+ and ₃PO₄-), so the total number of particles is 0.0232 x 2 = 0.0464 osmoles. Finally, we divide the number of osmoles by the volume of the solution in liters. We don't have the volume of the solution in the question, so we can't give an exact value for osmolarity. However, we can assume a volume (e.g. 100 mL) and calculate the osmolarity based on that. Assuming a volume of 100 mL (0.1 L), the osmolarity would be 0.0464/0.1 = 0.464 osmolar. However, this answer is not one of the multiple choice options. The closest option is C, 0.80 osmolar, which is higher than our calculated value but still the best choice out of the options given.

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