How do I prepare 1 L of 2 mol/L phenylmagnesium bromide?

Answer 1

Here are the theoretical calculations for 1 L of 2 mol/L PhMgBr.

PhBr + Mg → PhMgBr

#"2 mol PhMgBr" × "1 mol PhBr"/"1 mol PhMgBr" × "157.01 g PhBr"/"1 mol PhBr" × "1 mL PhBr"/"1.491 g PhBr" = "200 mL PhBr"#
#"2 mol PhMgBr" × "1 mol Mg"/"1 mol PhMgBr" × "24.30 g Mg"/"1 mol Mg" = "50 g Mg"#

One or two I₂ crystals

Sufficient dry THF to yield 1 L

You frequently use a large excess of Mg, up to two or three times the theoretical amount. Note: The I₂ acts as a catalyst for the reaction.

Because that is all you provided for the molarity of the solution, the calculated amounts can only have one significant figure. You will need to recalculate if you require more accuracy.

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Answer 2

To prepare 1 L of a 2 mol/L solution of phenylmagnesium bromide, you need to dissolve the appropriate amount of phenylmagnesium bromide (C6H5MgBr) in a solvent, typically ether or THF (tetrahydrofuran), to achieve the desired concentration.

First, calculate the molar mass of phenylmagnesium bromide:

  • Magnesium (Mg): 24.305 g/mol
  • Bromine (Br): 79.904 g/mol
  • Phenyl group (C6H5): 6 carbon atoms (12.011 g/mol each) + 5 hydrogen atoms (1.008 g/mol each) = 78.114 g/mol

Molar mass of phenylmagnesium bromide = Mg + Br + Phenyl group = 24.305 g/mol + 79.904 g/mol + 78.114 g/mol = 182.323 g/mol

Now, to prepare a 2 mol/L solution of phenylmagnesium bromide:

  1. Calculate the required mass of phenylmagnesium bromide using the formula: Mass (in grams) = molarity × volume (in liters) × molar mass = 2 mol/L × 1 L × 182.323 g/mol = 364.646 g

  2. Weigh out 364.646 g of phenylmagnesium bromide.

  3. Dissolve the weighed phenylmagnesium bromide in enough solvent (ether or THF) to make 1 L of solution.

  4. Mix the solution thoroughly until the phenylmagnesium bromide is completely dissolved.

  5. Once dissolved, the solution is now ready as a 2 mol/L phenylmagnesium bromide solution.

Ensure to follow appropriate safety procedures and protocols when handling chemicals, as phenylmagnesium bromide can react violently with water and air. Additionally, perform the preparation in a well-ventilated area and wear appropriate personal protective equipment.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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