Answer:
0.0639 g of Br₂ will be left
Step-by-step explanation:
The balance chemical equation for given synthesis reaction is,
2 Rb + Br₂ → 2 RbBr
Step 1: Calculate Moles of each reactant for given masses as;
Moles of Rb = 1 g ÷ 85.46 g/mol
Moles of Rb = 0.0117 moles
Similarly,
Moles of Br₂ = 1 g ÷ 159.80 g/mol
Moles of Br₂ = 0.00625 moles
Step 2: Find reactant in Excess as:
According to equation,
2 moles of Rb reacted with = 1 mole of Br₂
So,
0.0117 moles of Rb will react with = X moles of Br₂
Solving for X,
X = 0.0117 mol × 1 mol / 2 mol
X = 0.00585 mol of Br₂
While, as calculated above we are provided with 0.00625 moles of Br₂. Therefore, Br₂ is in excess and the excess amount is calculated as,
= Given Moles - Consumed Moles
= 0.00625 moles - 0.00585 moles
= 0.0004 moles
Step 3: Calculate mass of excess Br₂ as:
Mass = Moles × M.Mass
Mass = 0.0004 mol × 159.80
Mass = 0.0639 g of Br₂
Note: Speaking broadly, there will be 1.93 g of RbBr along with 0.0639 g of Br₂ because RbBr is being produced and is available along with unreacted Br₂.