Question

Which of the following is the odd one with regard to mass? (a) \(1 \mathrm{~g}\) atom of sulphur (b) \(0.5\) moles of \(\mathrm{CO}_{2}\) (c) 1 mole of \(\mathrm{O}_{2}\) (d) \(3 \times 10^{23}\) molecules of \(\mathrm{SO}_{2}\)

Short answer

Option (b) 0.5 moles of  is the odd one with 22 g mass.

Step-by-step solution

Identify Molar Masses

To solve this problem, we first need to know the molar masses of each substance. The molar mass of oxygen () is approximately 16 g/mol, so  is 32 g/mol. The molar mass of carbon dioxide () is approximately 44 g/mol (12 + 16*2). Sulfur () has a molar mass of 32 g/mol, and sulfur dioxide () has a molar mass of 64 g/mol (32 + 16*2).

Calculate Mass of Each Option

Now we calculate the masses for each option. (a) 1 gram atom of sulfur has a mass of 32 g. (b) 0.5 moles of : Mass = 0.5 * 44 = 22 g. (c) 1 mole of : Mass = 1 * 32 = 32 g. (d) For  molecules, calculate the number of moles: Number of moles = rac{3 imes 10^{23}}{6.022 imes 10^{23}}, so mass = 0.5 * 64 = 32 g.

Compare Masses

Compare the masses calculated for each option: - (a) 32 g - (b) 22 g - (c) 32 g - (d) 32 g. The option that has a significantly different mass is option (b) with 22 g.

Key concepts

Mole Concept

The mole concept is a cornerstone of chemistry that helps us understand the quantity of particles in a given substance. It's akin to a dozen in everyday language, but while a dozen refers to 12, a mole refers to Avogadro's number, which is approximately \[6.022 \times 10^{23}\]. This number is significant as it provides a link between the atomic scale and the macroscopic quantities we deal with in the lab or real life.

• One mole of any substance contains exactly \(6.022 \times 10^{23}\) particles, whether they are atoms, molecules, or ions.
• The mass of one mole of a substance in grams is equal to its molecular weight or formula mass.

For example, in the exercise provided, when calculating the mass of \(0.5\) moles of \(\mathrm{CO}_2\), we use its molar mass, which is \(44\, g/mol\). Therefore, \(0.5\) moles of \(\mathrm{CO}_2\) would weigh \(22\, g\). Thus, the mole concept enables precise measurements in chemical reactions.

Chemical Reactions

Chemical reactions involve the transformation of substances through the breaking and forming of bonds. This process is central to the study and application of chemistry. Understanding chemical reactions is essential for predicting how different substances will interact and change.

• Each chemical reaction can be described by a balanced chemical equation, where the number of atoms for each element is equal on both the reactant and product sides.
• The physical and chemical properties of the reactants are different from those of the products.

When considering the problem above, the calculation of molar masses involves understanding the composition of compounds like \(\mathrm{CO}_2\), \(\mathrm{SO}_2\), and their individual atomic weights, which are essential in predicting and analyzing reactions. Knowing the product's mass also helps in understanding the yield and efficiency of a chemical reaction.

Stoichiometry

Stoichiometry is the area of chemistry that uses the quantitative relationships between reactants and products in a chemical reaction. It allows chemists to predict the amounts of substances consumed and produced in a given reaction.

• To perform stoichiometric calculations, one needs to understand the concept of a mole and molar masses.
• It involves using balanced chemical equations to calculate the quantities of reactants and products.

In the provided exercise, stoichiometry helps determine which among the given options does not conform to the mass equivalency of substances. By calculating the mass of each mole ratio through stoichiometry, we predict and compare the mass of compounds like \(\mathrm{CO}_2\) and \(\mathrm{SO}_2\) against their molar proportions. Therefore, mastering stoichiometry enables a comprehensive understanding of chemical equations and their practical applications in both academic and industrial settings.