Question

Which solution contains the biggest amount in mol of chloride ions in 20cm³?

a) 0.1 M NaCl
b) 0.2 M CaCl₂
c) 0.15 M KCl
d) 0.25 M MgCl₂

Answer 1

To determine which solution contains the largest amount of moles of chloride ions, the moles of chloride in each solution are calculated. The 0.25 M MgCl₂ solution contains the highest amount of chloride ions at 0.01 moles in a 20 cm³ sample.

Step-by-step explanation:

The student's question involves comparing different solutions to determine which contains the largest amount of moles of chloride ions in a 20 cm³ (milliliters) sample. To solve this, we need to calculate the moles of chloride ions in each solution:

• 0.1 M NaCl - Each mole of NaCl contains 1 mole of Cl⁻. Thus, in 20 cm³ of 0.1 M NaCl, there are 0.1 mol/L * 0.020 L = 0.002 moles of Cl⁻.
• 0.2 M CaCl₂ - Each mole of CaCl₂ contains 2 moles of Cl⁻. Therefore, 0.2 mol/L * 0.020 L * 2 = 0.008 moles of Cl⁻.
• 0.15 M KCl - Similar to NaCl, KCl provides 1 mole of Cl⁻ per mole of KCl. Thus, 0.15 mol/L * 0.020 L = 0.003 moles of Cl⁻.
• 0.25 M MgCl₂ - Like CaCl₂, MgCl₂ yields 2 moles of Cl⁻ for every mole of MgCl₂. So, 0.25 mol/L * 0.020 L * 2 = 0.01 moles of Cl⁻.

Comparing all solutions, 0.25 M MgCl₂ contains the largest amount of chloride ions in 20 cm³, which is 0.01 moles.