(b) Which will contain the greater number of moles of potassium ion: 30.0 mL of 0.15 M K₂CrO₄ or 25.0 mL of 0.080 M K₃PO₄

Verified step by step guidance

1. Calculate the moles of K_2CrO_4 in 30.0 mL of 0.15 M solution using the formula: moles = concentration (M) \times volume (L).
2. Determine the number of moles of potassium ions (K^+) in K_2CrO_4 by recognizing that each formula unit of K_2CrO_4 contains 2 moles of K^+.
3. Calculate the moles of K_3PO_4 in 25.0 mL of 0.080 M solution using the formula: moles = concentration (M) \times volume (L).
4. Determine the number of moles of potassium ions (K^+) in K_3PO_4 by recognizing that each formula unit of K_3PO_4 contains 3 moles of K^+.
5. Compare the moles of potassium ions from both solutions to determine which contains the greater number of moles of potassium ion.

Key Concepts

Molarity (M)

Molarity is a measure of concentration defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L). Understanding molarity is essential for calculating the number of moles present in a given volume of solution, which is crucial for this question.

Stoichiometry

Stoichiometry involves the calculation of reactants and products in chemical reactions based on the balanced chemical equations. In this context, it helps determine the number of moles of potassium ions produced from the given compounds, K₂CrO₄ and K₃PO₄, by analyzing their formulas and the number of potassium ions they contain.

Conversion of Volume to Moles

To find the number of moles from a solution, one can use the formula: moles = molarity × volume (in liters). This conversion is necessary to compare the moles of potassium ions in the two solutions provided in the question, allowing for a direct comparison of their quantities.