Question

(a) Is the number of moles of ions present in a solution an intensive or an extensive property? (b) Can you identify which one between \(0.10 \mathrm{~mol} \mathrm{ZnCl}_{2}\) and \(0.1 \mathrm{M} \mathrm{ZnCl}_{2}\) contains more \(\mathrm{Zn}^{2+}\) ion? Why?

Short answer

(a) The number of moles of ions present in a solution is an extensive property, as it depends on the quantity of the substance. (b) We cannot identify which contains more Zn2+ ions since the volume of the solution for 0.1 M ZnCl2 is not provided.

Step-by-step solution

Understanding Intensive and Extensive Properties

Intensive properties are properties that do not depend on the quantity of matter, such as density, boiling point, or color. Extensive properties, on the other hand, depend on the amount of substance present. These include mass, volume, and the number of moles of a substance.

Determining Property of Moles of Ions in a Solution

The number of moles of ions in a solution depends on the quantity of the substance; therefore, it is an extensive property. Answer for part (a): The number of moles of ions present in a solution is an extensive property.

Understanding Mole and Molarity

Moles represent the quantity of a substance, while molarity represents the concentration of a substance in a solution, which is defined as moles of solute per liter of solution (\(\mathrm{M = \dfrac{moles}{L}}\)).

Identify the Total Amount of Zn2+ ions in Given Cases

In the first case, we have 0.10 mol ZnCl2. Each molecule of ZnCl2 dissociates into one Zn2+ ion and two Cl- ions. Therefore, the number of Zn2+ ions will be equal to the number of moles of ZnCl2, which is 0.10 mol. In the second case, we have 0.1 M ZnCl2 solution. To compare with the first case, we need to know the volume of solution in the second case. However, since the volume of solution is not provided, we cannot determine the number of moles of Zn2+ ions in the second case. Without this information, we cannot identify which case contains more Zn2+ ions. Answer for part (b): We cannot identify which contains more Zn2+ ions since the volume of the solution for 0.1 M ZnCl2 is not provided.

Key concepts

Moles of Ions

In chemistry, moles of ions refer to the quantity of ions present in a solution. This concept is crucial because it helps us understand how much of a substance is dissolved. Moles are a measure of the number of entities (like atoms or ions) in a substance. When dissolved, compounds typically dissociate into ions. For example, a molecule of ZnCl extsubscript{2} dissociates into one \[\mathrm{Zn}^{2+} \text{ ion and two } \mathrm{Cl}^{-} \text{ ions.}\] The number of moles of ions is an extensive property. This means it depends on the amount of solute present. If you double the substance, you double the moles of ions. Thus, understanding moles of ions enables us to predict the behavior and reactivity of solutions.
Keep in mind, the number of moles directly affects the properties and reactions of a solution.

Solution Concentration

Solution concentration tells us how much solute is present in a given volume of solvent. It's crucial to know, because it helps determine the strength of a solution. Concentration can be expressed in various ways: molarity, molality, and parts per million.

• Importance: Solution concentration is vital for calculating reaction yields and determining reaction rates.
• Applications: Used in industries for formulations, chemical reactions, and environmental monitoring.

Whether preparing a medical solution or diluting a chemical mix, knowing the concentration is essential. An accurate understanding ensures correct dosages and reaction outcomes.

Chemical Dissociation

Chemical dissociation is the process by which compounds split into their ions in a solution. It's crucial for understanding how substances interact when dissolved. For example, ZnCl extsubscript{2} dissociates as follows: \[\mathrm{ZnCl}_2 \rightarrow \mathrm{Zn}^{2+} + 2 \mathrm{Cl}^{-}\] This splitting is necessary for reactions in solutions, such as electrical conductivity and acid-base reactions.

• Electrical Conductivity: Dissociated ions move freely, allowing electricity to pass.
• Reaction Rates: Dissociation affects how quickly a reaction occurs.

Understanding dissociation helps predict how solutions will react and change under different conditions.

Molarity

Molarity is a common measure of solution concentration, defined as moles of solute per liter of solution. It's represented as M and calculated using the formula: \[M = \frac{\text{moles of solute}}{\text{liters of solution}}\] Molarity gives insight into how concentrated a solution is, guiding how it might react or be diluted.

• Measurement: Essential for laboratory settings where solutions need precise concentrations.
• Comparison: Helps in comparing different solutions and predictions in equilibrium reactions.

When working with solutions, molarity is a key value that affects preparation, reactivity, and outcome in chemical experiments.

Properties of Matter

Properties of matter help us understand and categorize different materials. They are divided into two main types: extensive and intensive properties.

• Extensive Properties: Depend on the amount of matter. Examples include mass, volume, and total moles.
• Intensive Properties: Independent of the amount of matter. Examples include density, boiling point, and color.

Knowing these properties is essential in fields like material science and engineering to predict how substances will behave. For instance, understanding that the number of moles of ions is an extensive property allows chemists to determine quantities necessary for reactions. Recognizing these properties helps with practical applications like chemical reactions, manufacturing, and quality control.