A compound with the formula XOCl2 reacts with water, yielding HCl and another acid H2XO3, which has two acidic hydrogens that react with NaOH. When 0.350 g of XOCl2 was added to 50.0 mL of water and the resultant solution was titrated, 96.1 mL of 0.1225 M NaOH was required to react with all the acid. (b) What are the atomic mass and identity of element X?

Verified step by step guidance

1. Determine the moles of NaOH used in the titration. Use the molarity and volume of the NaOH solution. The formula to calculate moles is: \( \text{Moles} = \text{Molarity} \times \text{Volume in liters} \).
2. Since H2XO3 has two acidic hydrogens, each mole of H2XO3 will react with two moles of NaOH. Use this stoichiometric relationship to calculate the moles of H2XO3 produced in the reaction.
3. Knowing the moles of H2XO3 and the fact that each mole of XOCl2 produces one mole of H2XO3, determine the moles of XOCl2 that reacted.
4. Calculate the molar mass of XOCl2 using the mass of XOCl2 given and the moles of XOCl2 calculated. The formula for molar mass is: \( \text{Molar Mass} = \frac{\text{Mass}}{\text{Moles}} \).
5. Determine the atomic mass of X by subtracting the masses of the oxygen and chlorine atoms from the molar mass of XOCl2. Use the known atomic masses of oxygen (16.00 g/mol) and chlorine (35.45 g/mol) for this calculation.

Key Concepts

Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions. It involves using balanced chemical equations to determine the relationships between the amounts of substances consumed and produced. In this question, stoichiometry is essential for understanding how the amounts of XOCl2, HCl, and H2XO3 relate to the volume and concentration of NaOH used in the titration.

Titration

Titration is a laboratory technique used to determine the concentration of a solute in a solution. It involves the gradual addition of a titrant (in this case, NaOH) to a solution until a reaction reaches completion, indicated by a color change or a specific endpoint. Understanding titration is crucial for calculating the moles of acid present in the solution, which will help identify the compound XOCl2 and the element X.

Acid-Base Reactions

Acid-base reactions involve the transfer of protons (H+) between reactants, resulting in the formation of water and a salt. In this scenario, HCl and H2XO3 are the acids produced from the reaction of XOCl2 with water. Recognizing the nature of these acids and their reactions with NaOH is vital for determining the total acidity of the solution and ultimately identifying the element X based on the stoichiometric relationships.