Problem 62 - Chemistry Matter and Change

Question

Write formulas for the following substances and designate their physical states. a. nitrogen dioxide gas b. liquid gallium c. barium chloride dissolved in water d. solid ammonium carbonate

Step-by-Step Solution

Answer

The chemical formulas along with their physical states are: a. Nitrogen dioxide gas: \(NO_2(g)\) b. Liquid gallium: \(Ga(l)\) c. Barium chloride dissolved in water: \(BaCl_2(aq)\) d. Solid ammonium carbonate: \((NH_4)_2CO_3(s)\)

Step 1: Write the chemical formula for nitrogen dioxide

Nitrogen dioxide is a compound made up of one nitrogen atom and two oxygen atoms. The chemical formula is NO_2.

Step 2: Designate the physical state of nitrogen dioxide

Since it is given that nitrogen dioxide is in the gaseous state, we can represent it as NO_2(g). #b. Liquid gallium#

Step 3: Write the chemical formula for gallium

Gallium is an element, so its chemical formula is Ga.

Step 4: Designate the physical state of liquid gallium

As given, gallium is in the liquid state, so we represent it as Ga(l). #c. Barium chloride dissolved in water#

Step 5: Write the chemical formula for barium chloride

Barium chloride is a compound made up of one barium atom and two chlorine atoms. The chemical formula is BaCl_2.

Step 6: Designate the physical state of barium chloride dissolved in water

Since it is dissolved in water, we represent it as BaCl_2(aq), where (aq) stands for aqueous, meaning dissolved in water. #d. Solid ammonium carbonate#

Step 7: Write the chemical formula for ammonium carbonate

Ammonium carbonate is a compound containing two ammonium ions (NH_4^+) and one carbonate ion (CO_3^{2-}). The chemical formula is (NH_4)_2CO_3.

Step 8: Designate the physical state of solid ammonium carbonate

Since it is given that ammonium carbonate is in the solid state, we represent it as (NH_4)_2CO_3(s).

Key Concepts

Physical States of Matter

The physical states of matter describe the different forms in which substances can exist. These states significantly influence how substances behave and interact. There are three primary states of matter: solid, liquid, and gas. The physical state of a substance can be represented in its chemical formula using a letter in parentheses:

• Solid is indicated by (s), characterized by a rigid structure and definite shape.


• Liquid is indicated by (l), having a fixed volume but taking the shape of its container.


• Gas is indicated by (g), with no fixed shape or volume, expanding to fill its container.

Understanding these states helps in predicting how substances will behave under different conditions. Thermal energy adds kinetic energy, causing substances to change states, such as from liquid to gas when heated.

Chemical Compounds

Chemical compounds are substances formed by the chemical combination of two or more elements. Each compound has a fixed composition and specific properties. The chemical formula of a compound conveys essential information about the elements that constitute it and their ratios. For example, nitrogen dioxide ( O_2) consists of one nitrogen atom and two oxygen atoms. This simple notation encapsulates the essence of the compound, such as its reactivity and properties.

Chemical compounds can be:

• Molecular compounds: typically formed by nonmetals sharing electrons, like nitrogen dioxide.


• Ionic compounds: formed by metals and nonmetals exchanging electrons, such as barium chloride (BaCl_2).

Recognizing chemical formulas helps understand the nature of compounds, predicting their reactions and interactions with other substances.

Aqueous Solutions

Aqueous solutions are a specific type of mixture where a substance is dissolved in water. The term "aqueous" refers to the presence of water as a solvent. In chemical formulas, aqueous solutions are denoted with (aq). This designation is crucial because it indicates the substance is dissolved, altering its properties and behavior compared to its undissolved state. For instance, barium chloride (BaCl_2) behaves differently when dissolved as BaCl_2(aq). The process of dissolving involves the interaction between solute particles and water molecules, dispersing the particles uniformly throughout the solution. This often affects conductivity, boiling, and freezing points, and reactivity. Understanding aqueous solutions is vital in both academic investigations and real-world applications, like in medicinal or industrial formulations.