Question

When figuring out the limiting reactant of the synthesis of Methyl Orange do I take into accout all 4 reactions or just sulfanilic acid + n,n -dimethylaniline?

Do I figure out the limiting reaction for each step like sodium carbonate + sulfanilic acid and proceed with limiting reactants all the way through?

Im starting with 0.5g of sulfanilic acid + 10ml of 2% aq sodium bicarbonate solution. Then 0.2g of sodium nitrite + 0.5ml of HCl. then 0.5 ml of N,N dimethylaniline and 0.5 ml of acetic acid to prepare the N,N dimethylaniline.

I hope this makes sense. Just trying to find the limiting reactant.

Thank you so much

S 0=$ CH3 0:5 N-CH₂ сн. CH₃ Diazotized sulfanilic acid 173.19 gland N,N-dimethylaniline 121. 18 gluol D=0.956g luL Methyl orange 306 glmol

Answer 1

When figuring out the limiting reactant of the synthesis of Methyl Orange do I take into accout all 4 reactions or just sulfanilic acid + n,n -dimethylaniline?

Answer: NO, only those reactants who give product is enough for limiting reactants and yield calculations.

Do I figure out the limiting reaction for each step like sodium carbonate + sulfanilic acid and proceed with limiting reactants all the way through?

Answer: NO, generally we will take excess of base like sodium carbonate to deprotonate sulfanilic acid and initiate reaction unless it creates multiple product formation.

Im starting with 0.5g of sulfanilic acid + 10ml of 2% aq sodium bicarbonate solution. Then 0.2g of sodium nitrite + 0.5ml of HCl. then 0.5 ml of N,N dimethylaniline and 0.5 ml of acetic acid to prepare the N,N dimethylaniline.

Answer: We will consider only 0.5g of sulfanilic acid & 0.5 ml of N,N dimethylaniline, in the end we will neutralize any excess acid or base to avoid further reactions.

Calculations:

moles present in 0.5g of sulfanilic acid = 0.5 g / 173.19 g/mol = 0.00288700271 mol

mass of 0.5 ml of N,N dimethylaniline = 0.5 mL x 0.956 g/mL = 0.478 g

moles present in 0.478 g of N,N dimethylaniline = 0.478 g / 121.18 g /mol = 0.0039445453 mol

as per chemical reaction equation 1 mol sulfanilic acid reacts with 1 mol N,N dimethylaniline and produces 1 mol Methyl Orange, so moles comparision of both reactants confirms that sulfanilic acid is the limiting reactant.

moles Methyl Orange produced = 0.00288700271 mol

mass of Methyl Orange produced = Theoretical yield

Theoretical yield = 0.00288700271 mol x 306 g/mol = 0.88 g

Percent yield = (your experimental yield in grams / Theoretical yield) x 100%

Hope this helped you!

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