Question

Thionyl chloride, \(\mathrm{SOCl}_{2}\), is used as a very powerful drying agent in many synthetic chemistry experiments in which the presence of even small amounts of water would be detrimental. The unbalanced chemical equation is $$ \mathrm{SOCl}_{2}(l)+\mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{HCl}(g) $$ Calculate the mass of water consumed by complete reaction of \(35.0 \mathrm{~g}\) of \(\mathrm{SOCl}_{2}\)

Short answer

The mass of water consumed by the complete reaction of 35.0 g of SOCl₂ is 5.89 g.

Step-by-step solution

Balance the chemical equation

To balance the chemical equation, we need to make sure the number of atoms of each element is the same on both sides of the equation. For the given equation: $$ \mathrm{SOCl}_{2}(l)+\mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{SO}_{2}(g)+\mathrm{HCl}(g) $$ We can see that there are the same number of S and O atoms on both sides. However, there are 2 H atoms and 2 Cl atoms on the left and only 1 H atom and 1 Cl atom on the right. To balance this equation, we can place a coefficient of 2 in front of HCl on the right side: $$ \mathrm{SOCl}_{2}(l)+\mathrm{H}_{2} \mathrm{O}(l) \rightarrow \mathrm{SO}_{2}(g)+2\mathrm{HCl}(g) $$ Now, the chemical equation is balanced.

Calculate the number of moles of SOCl₂

Now that we have the balanced chemical equation, we can use the given mass of SOCl₂ (35.0 g) to calculate the number of moles present. We'll use the molar mass of SOCl₂ which is: Molar mass of S = 32.06 g/mol Molar mass of O = 16.00 g/mol Molar mass of Cl = 35.45 g/mol Molar mass of SOCl₂: 32.06 + 16.00 + (2 × 35.45) = 106.92 g/mol Number of moles of SOCl₂ = (35.0 g) / (106.92 g/mol) = 0.327 mol

Determine the number of moles of H₂O consumed

According to the balanced chemical equation, 1 mole of SOCl₂ reacts with 1 mole of H₂O. Therefore, the number of moles of H₂O consumed is equal to the number of moles of SOCl₂. Number of moles of H₂O consumed = 0.327 mol

Calculate the mass of H₂O consumed

To find the mass of H₂O consumed, we can multiply the number of moles by its molar mass (Molar mass of H₂O = 18.02 g/mol). Mass of H₂O consumed = (0.327 mol) × (18.02 g/mol) = 5.89 g Thus, the mass of water consumed by the complete reaction of 35.0 g of SOCl₂ is 5.89 g.

Key concepts

Chemical Equations

Chemical equations are the backbone of chemistry. They represent chemical reactions by using symbols for the elements and formulas for the compounds. In our example of a reaction involving thionyl chloride (\(\mathrm{SOCl}_2\)) and water (\(\mathrm{H}_2 \mathrm{O}\)), the chemical equation is used to show the reactants transforming into products: sulfur dioxide (\(\mathrm{SO}_2\)) and hydrochloric acid (\(\mathrm{HCl}\)).

• The left side of the equation includes the reactants, which are the starting substances.
• The right side shows the products, which are substances formed by the reaction.
• Each substance in the reaction is represented by its chemical formula, such as \(\mathrm{SOCl}_2\), which reveals its composition.

When writing chemical equations, the reactants are separated from the products by an arrow (\( \rightarrow \)). This indicates the direction of the reaction. To fully understand a chemical equation, one must balance it, ensuring the conservation of mass and atoms.

Mole Calculations

Mole calculations are crucial to determine the amount of substances involved in chemical reactions. The mole is a unit that helps quantify substances in chemistry, making it easier to balance and calculate equations.
To find out how much of a substance interacts in a chemical reaction, we use the concept of moles along with the molar mass.

• For example, the molar mass of \(\mathrm{SOCl}_2\) is calculated by adding the atomic masses of one sulfur (32.06 g/mol), one oxygen (16.00 g/mol), and two chlorines (2 \times 35.45 g/mol), resulting in 106.92 g/mol.
• Using this molar mass, we can determine the moles of \(\mathrm{SOCl}_2\) by dividing the given mass by the molar mass. In our case, 35.0 grams of \(\mathrm{SOCl}_2\) is equivalent to 0.327 moles, calculated as 35.0 g / 106.92 g/mol.

Mole calculations allow chemists to predict how much of each reactant is needed or product produced by a reaction, which is vital for laboratory and industrial applications.

Reaction Balancing

Balancing chemical reactions is a foundational step in ensuring that a chemical equation adheres to the law of conservation of mass, which states that mass cannot be created or destroyed in a closed system.
In balancing reactions, we adjust the coefficients in front of chemical formulas to ensure that the number of atoms for each element is equal on both sides of the equation.

• For instance, in the equation \(\mathrm{SOCl}_2(l) + \mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{SO}_2(g) + \mathrm{HCl}(g)\), we initially observe that hydrogen and chlorine atoms are unbalanced.
• To balance hydrogen and chlorine, we place a coefficient of 2 in front of \(\mathrm{HCl}(g)\), making the equation \(\mathrm{SOCl}_2(l) + \mathrm{H}_2\mathrm{O}(l) \rightarrow \mathrm{SO}_2(g) + 2\mathrm{HCl}(g)\).

Balancing ensures not only that the law of conservation is upheld, but also that stoichiometric calculations can be accurately performed. It's an essential skill for solving chemical problems and being successful in chemistry studies.