Question

What volume of \(0.105 \mathrm{N} \mathrm{H}_{3} \mathrm{PO}_{4}\) is required to neutralize \(18.7 \mathrm{mL}\) of \(0.204 \mathrm{M} \mathrm{NaOH}\) solution?

Short answer

Approximately \(35.94 \mathrm{mL}\) of \(0.105 \mathrm{N} \mathrm{H}_{3} \mathrm{PO}_{4}\) solution is required to neutralize \(18.7 \mathrm{mL}\) of \(0.204 \mathrm{M} \mathrm{NaOH}\) solution.

Step-by-step solution

Identify the given values

In this problem, we are given the following: n1 = 0.105 N (normality of H3PO4) v1 (volume of H3PO4) - This is the value we need to find n2 = 0.204 M (concentration of NaOH) v2 = 18.7 mL (volume of NaOH)

Convert Molarity to Normality for NaOH solution

Molarity and normality are related by: Normality = Molarity * No. of OH- ions in the chemical formula Since NaOH has only one OH- ion, its normality is the same as its molarity. n2 = 0.204 N

Use the neutralization formula to find the volume of H3PO4

Now, we can use the neutralization formula (n1 * v1 = n2 * v2) to find the volume of H3PO4 (v1) required to neutralize the given volume of NaOH solution. We can plug in the known values into the formula: 0.105 * v1 = 0.204 * 18.7 Now, we solve for v1 by dividing both sides of the equation by 0.105: v1 = (0.204 * 18.7) / 0.105

Calculate the final volume of H3PO4

By solving for v1, we find: v1 ≈ 35.94 mL So, approximately 35.94 mL of 0.105 N H3PO4 solution is required to neutralize 18.7 mL of 0.204 M NaOH solution.

Key concepts

Acid-Base Neutralization

Acid-base neutralization is a fundamental chemical process in which an acid and a base react to form water and a salt. This type of reaction is important in various fields including chemistry, biology, medicine, and environmental science. Neutralization occurs when the hydrogen ions (H+) from the acid combine with the hydroxide ions (OH-) from the base to create water (H2O).

The general equation for an acid-base neutralization reaction is:
\[\text{acid} + \text{base} \rightarrow \text{water} + \text{salt}\]
Understanding neutralization is key in calculating the amount of an acidic or basic solution needed to neutralize the other. This is especially useful in titration experiments in chemistry labs, where the goal is to determine the concentration of an unknown solution by neutralizing it with a solution of known concentration.

Normality

Normality (N) is a measure of concentration that expresses the number of equivalents of reactive species per liter of solution. It's related to molarity, but while molarity refers to the number of moles of solute per liter, normality considers the reactivity (equivalents) of the solute.

For acid-base reactions, one equivalent of an acid or a base is the amount that will donate or accept one mole of hydrogen ions (H+) or hydroxide ions (OH-), respectively. For an acid like H3PO4, which has three acidic protons, the number of equivalents is three times the molarity because it can potentially release three moles of H+ ions per mole of acid.

The formula to convert molarity to normality for an acid or base is:
\[ Normality = Molarity \times n \]
where \( n \) is the number of equivalents. For bases like NaOH, where there is only one equivalent per mole of solute, the normality is equal to the molarity.

Molarity

Molarity (M) is another measure of concentration, expressed as the number of moles of a solute per liter of solution. It's a fundamental concept in chemistry used to describe the concentration of compounds in solution. The formula to calculate molarity is:
\[Molarity (M)=\frac{moles \ of \ solute}{liters \ of \ solution}\]
In practice, knowing the molarity of a solution allows scientists and students to calculate how much of a chemical is present in a given volume of solution. This is particularly important in quantitative analysis and chemical reactions where precise reactant quantities are crucial for the desired outcomes.

In titration and neutralization calculations, molarity can be used to determine the volume or the amount of one reactant needed to completely react with another based on stoichiometry.

Chemical Stoichiometry

Chemical stoichiometry involves the calculation of the relative quantities of reactants and products involved in a chemical reaction. It is grounded in the law of conservation of mass, which states that matter is neither created nor destroyed in a chemical reaction. Therefore, the amount of reactants must equal the amount of products.

Stoichiometry uses the balanced chemical equation to understand the ratio of reactants and products. This allows for calculations on how much of a reactant is needed to react with a certain amount of another reactant, or what volume of product will be produced.

The stoichiometric coefficients in a balanced chemical equation indicate the proportions of each substance in the reaction. For example, in a neutralization reaction between an acid and a base, stoichiometry helps determine the volume of acid needed to neutralize a known volume of a base with a known concentration, which ties into the problem at hand where we calculate the volume needed for neutralization using the chemical stoichiometry derived from the reaction's balanced equation.