What volume of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid according to the equation:

H3PO4(aq) + 3NaOH(aq) + Na3PO4(aq) + 3H2O(aq)

A) O 0.05 L
B) O6.93 L
C) O0.44 L
D) 03.01 L
E) 436.43 L

Taking into account the definition of molarity and the stoichiometry of the reaction, the correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.

The balanced reaction is:

H₃PO₄ (aq) + 3 NaOH (aq) → Na₃PO₄ (aq) + 3 H₂O(aq)

Then, by stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

Molarity is the number of moles of solute that are dissolved in a given volume.

Molarity is determined by:

 Molarity is expressed in units .

In this case, 0.42 L of 2.39 M phosphoric acid reacts. So, by definition of molarity, the number of moles that participate in the reaction is calculated as:

Solving:

number of moles of phosphiric acid= 2.39 * 0.42 liters

number of moles of phosphiric acid= 1.0038 moles ≅ 1 mole

Approaching 1 mole of the amount of phosphoric acid required, then by stoichiometry of the reaction, 3 moles of NaOH are necessary to react with 1 mole of the acid.

Then by definition of molarity and knowing that 6.9 M NaOH is needed, you can calculate the necessary volume amount of NaOH by:

Solving:

6.9 * volume= 3 moles

volume= 0.44 L

The correct option is option C) 0.44 L of 6.9 M NaOH is needed to completely titrate 0.42 L of 2.39 M phosphoric acid.

Learn more about molarity with this example:

heat or electricity in the atmosphere- c.

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