Anhydrous conditions are vital for a successful Grignard synthesis. To demonstrate this point, calculate the mass of water it would take to
destroy the phenylmagnesium bromide that synthesized from 0.48 mL of bromobenzene and 112.5 mg of magnesium. What is the volume of this amount of water?
To calculate the mass of water required to destroy phenylmagnesium bromide, we need to determine the moles of phenylmagnesium bromide formed and then use stoichiometry to find the moles of water needed. Finally, we can convert moles of water to mass and calculate the volume of water using the density of water.
First, let's calculate the moles of bromobenzene and magnesium:
Moles of bromobenzene = volume (in L) × density (in g/mL) / molar mass (in g/mol)
Given:
Volume of bromobenzene = 0.48 mL
Density of bromobenzene = unknown
Molar mass of bromobenzene = unknown
We need the density and molar mass of bromobenzene to proceed with the calculation. Please provide these values.
Note: Molar mass and density can be found in reference sources or using experimental data.
To calculate the mass of water required to destroy the phenylmagnesium bromide, we need to determine the number of moles of phenylmagnesium bromide formed first.
Step 1: Calculate the moles of bromobenzene:
Given that the volume of bromobenzene used is 0.48 mL and assuming a density of 1 g/mL, we can calculate the mass of bromobenzene:
Mass of bromobenzene = volume × density = 0.48 mL × 1 g/mL = 0.48 g
The molar mass of bromobenzene is 157.01 g/mol, so the moles of bromobenzene are:
Moles of bromobenzene = mass / molar mass = 0.48 g / 157.01 g/mol = 0.00306 mol
Step 2: Calculate the moles of magnesium:
The mass of magnesium used is given as 112.5 mg, which is equal to 0.1125 g.
The molar mass of magnesium is 24.31 g/mol, so the moles of magnesium are:
Moles of magnesium = mass / molar mass = 0.1125 g / 24.31 g/mol = 0.00463 mol
Step 3: Calculate the limiting reagent:
The stoichiometry between bromobenzene and phenylmagnesium bromide is 1:1. From step 1, we have 0.00306 moles of bromobenzene. From step 2, we have 0.00463 moles of magnesium. The limiting reagent is bromobenzene, as it has the smaller number of moles.
Step 4: Calculate the moles of phenylmagnesium bromide formed:
Since the limiting reagent is bromobenzene and the reaction is 1:1 with phenylmagnesium bromide, the moles of phenylmagnesium bromide formed will also be 0.00306 moles.
Step 5: Calculate the moles of water required to destroy the phenylmagnesium bromide:
The reaction between phenylmagnesium bromide and water is 1:1. Therefore, the number of moles of water required to destroy the phenylmagnesium bromide would be 0.00306 moles.
Step 6: Calculate the mass of water:
The molar mass of water is 18.02 g/mol. So, the mass of water required can be calculated as:
Mass of water = moles of water × molar mass = 0.00306 mol × 18.02 g/mol = 0.05524 g
Step 7: Calculate the volume of water:
Assuming the density of water is 1 g/mL, the volume of water required can be calculated as:
Volume of water = mass of water / density = 0.05524 g / 1 g/mL = 0.05524 mL
Therefore, it would take approximately 0.05524 g (or 0.05524 mL) of water to destroy the phenylmagnesium bromide synthesized from 0.48 mL of bromobenzene and 112.5 mg of magnesium.