Final answer:
3.275 moles of MgBr₂ are needed to completely react with 6.55 moles of AgNO₃ based on the 1:2 molar ratio of MgBr₂ to AgNO₃ in the reaction equation.
Step-by-step explanation:
To determine how many moles of MgBr₂ are required to react completely with 6.55 moles of AgNO₃, we need to look at the stoichiometry of the reaction between magnesium bromide and silver nitrate. The reaction is as follows:
MgBr₂ + 2 AgNO₃ → 2 AgBr + Mg(NO₃)₂
This shows that one mole of MgBr₂ reacts with two moles of AgNO₃. Therefore, to completely react with 6.55 moles of AgNO₃, half the amount of MgBr₂ would be needed because the molar ratio is 1:2 (MgBr₂:AgNO₃). Thus,
6.55 moles AgNO₃ × (1 mole MgBr₂ / 2 moles AgNO₃) = 3.275 moles of MgBr₂
The correct answer is 3.275 moles of MgBr₂.