Problem 13 - Chemistry A Guided Inquiry

Question

Based on your answers to CTQ 12, calculate: a) the mass (in grams) of one mole of methane molecules (to two decimal places). Show your work. b) the mass (in grams) of one mole of carbon tetrachloride molecules (to two decimal places). Show your work.

Step-by-Step Solution

Answer

Therefore, the mass of one mole of Methane (CH4) molecules is 16.05 g, and the mass of one mole of Carbon tetrachloride (CCl4) molecules is 153.81 g.

Step 1: Identify the molar mass of each element

Firstly, get the molar mass of each element in the molecules. The molar mass of Carbon (C) is approximately 12.01 g/mol, that of Hydrogen (H) is 1.01 g/mol, and the molar mass of Chloride (Cl) is 35.45 g/mol. The mole in a chemical substance can be determined using Avogadro's number, which is approximately \(6.022 \times 10^{23}\) entities.

Step 2: Calculate the molar mass of one mole of Methane (CH4) molecules

A Methane molecule (CH4) is composed of one Carbon atom and four Hydrogen atoms. Therefore, the total weight of one mole of Methane (CH4) molecules is given by the sum of the molar mass of one mole of Carbon (C) and four moles of Hydrogen (H). So, the molar mass of methane = Molar mass of Carbon + 4 * Molar mass of Hydrogen = 12.01 g/mol + 4 * 1.01 g/mol = 16.05 g/mol.

Step 3: Calculate the molar mass of one mole of Carbon tetrachloride (CCl4) molecules

A Carbon tetrachloride molecule (CCl4) consists of one Carbon atom and four Chlorine atoms. Thus, the entire mass of one mole of Carbon tetrachloride E(CCl4) molecules is obtained by adding the molar mass of one mole of Carbon (C) and four moles of Chlorine (Cl), i.e. molar mass of carbon tetrachloride = Molar mass of Carbon + 4 * Molar mass of Chlorine = 12.01 g/mol + 4 * 35.45 g/mol = 153.81 g/mol.

Key Concepts

Mole Concept

The mole concept is essential in chemistry for understanding how substances react and combine. A "mole" in chemistry is a unit that helps us count particles, much like a dozen counts for eggs. A mole is defined by Avogadro's number, which is approximately \(6.022 \times 10^{23}\) entities, representing atoms, molecules, ions, or other particles.

• The mole allows chemists to predict the mass of a substance needed for a chemical reaction.
• It connects microscopic atomic scale activities to macroscopic observable properties, such as mass.
• One mole of any substance will have its molar mass in grams equal to its relative atomic or molecular mass.

This concept simplifies calculations in stoichiometry, where we balance chemical equations by measuring out reactants in moles. Understanding the mole concept makes it easier to grasp how reactants convert to products and how mass relates to substance quantity.

Chemical Compounds

Chemical compounds consist of two or more different types of atoms bonded together, forming unique substances with specific properties. Based on their composition, compounds can be organic, such as methane \((\text{CH}_4)\), or inorganic like carbon tetrachloride \((\text{CCl}_4)\).

• Methane is a simple organic compound made of one carbon atom bonded to four hydrogen atoms.
• Carbon tetrachloride is an organic compound with one carbon atom bonded to four chlorine atoms.

The properties of compounds depend on the elements within them and how these elements are bonded. For example, changing the bonding in methane dramatically alters its properties. When calculating the molar mass of compounds, sum the molar masses of each constituent element, considering the number of each type of atom.

Avogadro's Number

Avogadro's number is a fundamental constant in chemistry, approximating \(6.022 \times 10^{23}\), defining the number of units in one mole of any substance. Named after the scientist Amedeo Avogadro, this number links the macroscopic scale that we can observe to the microscopic world of atoms and molecules.

• Avogadro's number allows us to convert between the number of atoms/molecules and the grams of a substance.
• It provides a bridge enabling us to comprehend the immense number of atoms in a tangible amount of material.

When using Avogadro's number, the vastness of atomic quantities shrinks into comprehendible gram amounts, simplifying calculations in chemistry. Whether calculating the number of particles in a given mass or understanding the scale of chemical reactions, Avogadro's constant is an indispensable tool in the chemist's toolkit.