What is the correct value for the weight of Na₃PO₄needed to make 100 mL of a 0.50 molar solution? A) 16.4 g B) 8.2 g C) 0.05 g D) 82 g E) 4.1 g

Question

Quizplus · Accepted Answer

To calculate the amount of Na₃PO₄ needed, we need to use the formula: mass (in grams) = molarity x volume (in liters) x molecular weight First, we need to convert the volume from milliliters to liters: 100 mL = 0.1 L Next, we can plug in the values we know: mass = 0.50 mol/L x 0.1 L x molecular weight Simplifying, we get: mass = 0.05 x molecular weight Now, we need to find the molecular weight of Na₃PO₄: Na = 22.99 g/mol S = 32.06 g/mol O = 15.99 g/mol P = 30.97 g/mol Adding these together, we get a molecular weight of: MW = 22.99 + (2 x 32.06) + 15.99 + 30.97 = 134.08 g/mol Plugging this back into our equation, we get: mass = 0.05 x 134.08 = 6.704 g We should round this to two significant figures, since the molarity only has two significant figures: mass = 6.7 g Therefore, the correct answer is B) 8.2 g.

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What Is the Correct Value for the Weight of Na₃PO₄