To find the number of moles of CaBr2 that remained, we need to determine the limiting reactant (the reactant that is completely consumed) and then use the stoichiometry of the balanced equation to calculate the number of moles.
Step 1: Calculate the number of moles of CaBr2 and SO42- using the given volumes and concentrations.
Number of moles of CaBr2 = volume (L) × concentration (mol/L)
= 0.380 L × 0.4294 mol/L
= 0.163532 mol
Number of moles of SO42- = volume (L) × concentration (mol/L)
= 0.250 L × 0.5880 mol/L
= 0.147 mol
Step 2: Use the stoichiometry of the balanced equation to determine the mole ratio between CaBr2 and SO42-.
From the balanced equation: Al2(SO4)3(aq) + 3 CaBr2(aq) → 2 AlBr3(aq) + 3 CaSO4(s)
The mole ratio between CaBr2 and SO42- is 3:1.
Step 3: Determine the limiting reactant.
To find the limiting reactant, compare the mole ratios between CaBr2 and SO42-. Since the ratio is 3:1, we need 3 moles of CaBr2 for every 1 mole of SO42-.
Using the mole ratios, we can see that we have excess SO42- (0.147 mol) compared to the available CaBr2 (0.163532 mol). Hence, CaBr2 is the limiting reactant.
Step 4: Calculate the number of moles of CaBr2 that remained.
Since CaBr2 is the limiting reactant, it is completely consumed in the reaction. Therefore, the number of moles of CaBr2 that remained is zero.