Question

Calculate the normality of each of the following solutions. a. \(0.134 M \mathrm{NaOH}\) b. \(0.00521 M \mathrm{Ca}(\mathrm{OH})_{2}\) c. \(4.42 M \mathrm{H}_{3} \mathrm{PO}_{4}\)

Short answer

The normality of each solution is: a. Sodium Hydroxide (NaOH): 0.134 N b. Calcium Hydroxide (Ca(OH)2): 0.01042 N c. Phosphoric Acid (H3PO4): 13.26 N

Step-by-step solution

Identify the number of hydrogen ions or hydroxide ions in each solution

For all three solutions, we must check how many hydrogen ions or hydroxide ions are in each compound. For NaOH, there is 1 hydroxide ion (OH-). For Ca(OH)2, there are 2 hydroxide ions (2OH-). For H3PO4, there are 3 hydrogen ions (3H+).

Calculate the normality for each solution

Normality is calculated by multiplying the molarity of the solution by the number of hydrogen or hydroxide ions present in the compound. a. Sodium Hydroxide (NaOH) Normality = Molarity × number of hydroxide ions Normality = \(0.134 M \times 1\) Normality = 0.134 N b. Calcium Hydroxide (Ca(OH)2) Normality = Molarity × number of hydroxide ions Normality = \(0.00521 M \times 2\) Normality = 0.01042 N c. Phosphoric Acid (H3PO4) Normality = Molarity × number of hydrogen ions Normality = \(4.42 M \times 3\) Normality = 13.26 N

Write down the answers

The normality of each solution: a. Sodium Hydroxide (NaOH): 0.134 N b. Calcium Hydroxide (Ca(OH)2): 0.01042 N c. Phosphoric Acid (H3PO4): 13.26 N

Key concepts

Solution Concentration

When we talk about solution concentration, we are referring to the amount of a substance present in a specific volume of solution. This allows us to describe how 'strong' or 'dilute' a solution is.
One of the most common ways to measure solution concentration is by molarity, which denotes the number of moles of solute per liter of solution. However, normality is another way to express concentration, particularly useful when dealing with reactions involving acid and base neutralization.
In our examples, knowing the normality of Sodium Hydroxide, Calcium Hydroxide, and Phosphoric Acid gives insights into their reaction capacity based on the available hydrogen or hydroxide ions.

Hydrogen Ions

Hydrogen ions ( ext{H}^+) play a crucial role in determining the reactivity of acids. The more hydrogen ions a solution has, generally the stronger the acid and its ability to cause chemical reactions.
For example, Phosphoric Acid (H extsubscript{3}PO extsubscript{4}) provides three hydrogen ions, showing its potential to donate these ions in reactions. In this way, understanding the number of dissociable hydrogen ions helps in predicting the normality of the solution.
Thus, calculating normality in Phosphoric Acid involves its molarity and the three hydrogen ions, resulting in a high normality value, indicative of its strong reactive nature.

Hydroxide Ions

The hydroxide ion ( ext{OH}⁻) is an integral part of understanding base reactions. When bases dissolve in water, they release hydroxide ions, which can neutralize acids.
For instance, in Sodium Hydroxide (NaOH) and Calcium Hydroxide (Ca( ext{OH}) extsubscript{2}), these compounds release hydroxide ions that define their base characteristics. NaOH releases one hydroxide ion, while Ca( ext{OH}) extsubscript{2} provides two, allowing Ca( ext{OH}) extsubscript{2} to neutralize twice as many hydrogen ions.
Recognizing the number of hydroxide ions can help determine the normality of these solutions, where higher numbers of ions result in increased normality.

Molarity

Molarity is a fundamental concept in chemistry involving the concentration of a solute in a solution. It is particularly useful for calculating how much of a substance is present and is defined as moles of solute per liter of solution.
For example, a 0.134 M solution of Sodium Hydroxide contains 0.134 moles of NaOH in one liter. Molarity simplifies calculations related to chemical equations and reactions, as seen when converting molarity to normality.
In our exercise, we used molarity as a starting point to calculate the normality of solutions, showing its importance in understanding solution behaviors and interacting compounds.

Chemical Compounds

Chemical compounds consist of two or more elements bonded together, representing matter's basic form. In the context of solution chemistry, these compounds dissolve in solvents like water, forming solutions with significant chemical implications.
Compounds like Sodium Hydroxide, Calcium Hydroxide, and Phosphoric Acid contribute to solution properties through their ability to dissociate and release ions.
Understanding the makeup and behavior of these compounds helps us calculate properties like normality, allowing us to predict how these solutions will behave in various chemical reactions, ensuring that calculations like those for molarity and concentration are accurate and applicable in practical scenarios.