Problem 176 - Introductory Chemistry Atoms First

Question

Identify the solvent and the solute in each solution: (a) Brass, which is 60 to \(80 \% \mathrm{Cu}\), and 18 to \(40 \% Z n\) (b) Household ammonia cleaner, which is \(1 \%\) by mass ammonia gas in water (c) \(2.59 \mathrm{~g}\) of sucrose in \(1.00 \mathrm{~g}\) of water at \(50^{\circ} \mathrm{C}\)

Step-by-Step Solution

Answer

(a) Solvent: Copper (Cu), Solute: Zinc (Zn) (b) Solvent: Water (H2O), Solute: Ammonia gas (NH3) (c) Solvent: Water (H2O), Solute: Sucrose (C12H22O11)

Step 1: Identifying solvent and solute in Solution (a)

For a brass solution, which contains 60 to 80% Copper (Cu) and 18 to 40% Zinc (Zn), we have to determine which component is present in the highest amount, which will make it the solvent. Since the percentage of Copper ranges from 60 to 80% and Zinc ranges from 18 to 40%, there is a higher amount of Copper in the solution. Therefore, the solvent in this solution is Copper (Cu), and the solute is Zinc (Zn).

Step 2: Identifying solvent and solute in Solution (b)

In the case of a household ammonia cleaner, the solution contains 1% by mass Ammonia gas in water. Since there is a larger amount of water compared to the ammonia gas, water acts as the solvent in this solution, and ammonia gas (NH3) is considered to be the solute.

Step 3: Identifying solvent and solute in Solution (c)

Lastly, in this solution, we have 2.59 g of sucrose (C12H22O11) dissolved in 1.00 g of water at 50°C. In this case, despite water being present in a lower amount, because water is the medium in which sucrose is dissolved, it is considered the solvent. Therefore, the solvent in this solution is water (H2O), and the solute is sucrose (C12H22O11).

Key Concepts

Brass Composition

Brass is an interesting alloy that we encounter in everyday objects such as door handles and musical instruments. It is primarily composed of copper and zinc. In a brass solution, the component that is present in the larger proportion acts as the solvent. In typical brass, copper makes up 60% to 80% of the mixture, while zinc comprises about 18% to 40%. This means that copper is more abundant and thereby acts as the solvent. Thus, zinc serves as the solute. Understanding the composition of brass helps us appreciate its flexibility and strength, which are benefits derived from the combination of its two components.

Ammonia Solution

Household ammonia cleaners are a common example of a solution where gases are dissolved in liquids. These solutions typically contain 1% ammonia gas by mass dissolved in water. Here, water is present in a much larger amount and serves as the solvent. Ammonia gas, even though in a gaseous state, acts as the solute.

The distinctive characteristic of such solutions is how a small amount of ammonia can significantly alter the properties of water, making it an effective cleaner. The water, in this case, provides a medium for the ammonia to disperse, which allows it to interact with surfaces for cleaning purposes.

Sucrose in Water

The solution of sucrose in water demonstrates a fascinating aspect of solutions, where the solvent is not always the most abundant component by mass. Here, 2.59 g of sucrose is dissolved in 1.00 g of water at a temperature of 50°C. Despite the larger mass of sucrose, water acts as the solvent. This is because it is the medium in which the dissolving process occurs.

This type of solution highlights the principle that the solvent is typically the substance that defines the state of the solution, whether solid, liquid, or gas. Thus, in liquid solutions such as this one, water remains the solvent while sucrose is the solute, emphasizing the solvent's role in the dissolving process.

Solution Chemistry

Solution chemistry is the study of homogeneous mixtures where one substance is dissolved in another. The solvent, which is usually in a larger quantity, is the medium in which the solute is dispersed. Understanding solution chemistry helps explain everyday processes like how sugar dissolves in tea or how salt dissolves in water.

Key points in solution chemistry involve determining which component in a solution is the solvent or solute, which depends not only on concentration but sometimes on the context of the solution, such as the medium used. Grasping these principles is crucial because solutions play a significant role in chemical reactions, biological processes, and industrial applications. Solutions can involve various states of matter but are defined by the uniform mixing of solute and solvent.