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A 50.0 mL sample of a 0.200 M aqueous solution of Na3PO4 was added to 50.0 mL of a 0.100 M aqueous solution of BaCl2. The mixture was stirred and the precipitate was collected, dried carefully, and weighed. How many grams of precipitate should be obtained

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Answer:

1.02 grams

Explanation:

The reaction between Na₃PO₄ and BaCl₂ is:

2Na₃PO₄(aq) + 3BaCl₂(aq) → Ba₃(PO₄)₂(s) + 6NaCl(aq)            

We need to find the number of moles of Na₃PO₄ and BaCl₂:

[tex] n_{Na_{3}PO_{4}} = C*V = 0.200 M*0.050 L = 0.01 moles [/tex]

[tex] n_{BaCl_{2}} = C*V = 0.100 M*0.050 L = 0.005 moles [/tex]

Now, we need to find the limiting reactant:

[tex] n_{Na_{3}PO_{4}} = \frac{2}{3}*0.005 moles = 0.0033 moles [/tex]

We have that it is needed 0.0033 moles of Na₃PO₄ to react with BaCl₂ and we have 0.01 moles of Na₃PO₄, so the limiting reactant is BaCl₂.

The number of moles of Ba₃(PO₄)₂ is:

[tex] n_{Ba_{3}(PO_{4})_{2}} = \frac{0.005}{3} = 0.0017 moles [/tex]

Finally, the mass of Ba₃(PO₄)₂ is:

[tex] m = n_{Ba_{3}(PO_{4})_{2}}*M = 0.0017 moles*601.93 g/mol = 1.02 g [/tex]

Therefore, should be obtained 1.02 grams of the precipitate.

I hope it helps you!

The mass of the precipitate that should be obtained is 1.005 g

First, we will write the balanced chemical equation for the reaction.  

The balanced chemical equation for the reaction is  

2Na₃PO₄ + 3BaCl₂ → Ba₃(PO₄)₂ + 6NaCl

This means 2 moles of Na₃PO₄ react with 3 moles of BaCl₂ to produce 1 mole of Ba₃(PO₄)₂ and 6 moles of NaCl

Now, we will determine the number of moles of each reactant present

For Na₃PO₄

Volume = 50.0 mL = 0.050 L

Concentration = 0.200 M

From the formula

Number of moles = Concentration × Volume

∴ Number of moles of Na₃PO₄ present = 0.200 × 0.050

Number of moles of Na₃PO₄ present = 0.01 mole

For BaCl₂

Volume = 50.0 mL = 0.050 L

Concentration = 0.100 M

∴ Number of moles of BaCl₂ present = 0.100 × 0.050

Number of moles of BaCl₂ present = 0.005 mole

Since

2 moles of Na₃PO₄ react with 3 moles of BaCl₂ to produce 1 mole of Ba₃(PO₄)₂

Then,

[tex]\frac{0.005\times 2}{3}[/tex] mole of Na₃PO₄ react with 0.005 mole of BaCl₂ to produce [tex]\frac{0.005}{3}[/tex] mole of Ba₃(PO₄)₂

That is,

0.0033 mole of Na₃PO₄ react with 0.005 mole of BaCl₂ to produce 0.00167 mole of Ba₃(PO₄)₂

Number of moles of the precipitate [Ba₃(PO₄)₂] formed is 0.00167 mole

Now, for the mass of the precipitate that should be formed

Using the formula

Mass = Number of moles × Molar mass

Molar mass of Ba₃(PO₄)₂ = 601.93 g/mol

∴ Mass of the precipitate that should be produced = 0.00167 × 601.93

Mass of the precipitate that should be produced = 1.005 g

Hence, the mass of the precipitate that should be obtained is 1.005 g

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