How do you approach question M1 in 6th edition book?

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MedhaVallurupalli1F
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How do you approach question M1 in 6th edition book?

Postby MedhaVallurupalli1F » Wed Jun 26, 2019 12:53 am

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I know we have to go through the limiting reactant steps, but how do you do this if you are not given the mass of the second reactant?

Chem_Mod
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Re: How do you approach question M1 in 6th edition book?

Postby Chem_Mod » Wed Jun 26, 2019 9:51 am

The question states that the ammonia reacts with an excess of hypochlorite ions. Therefore, ammonia must be the limiting reactant and the hypochlorite ions will be in excess so you do not need the mass of the hypochlorite ions to determine the percentage yield of hydrazine. Convert the 35.0 g of ammonia to moles of ammonia and use the mole to mole ratios and molar mass of hydrazine to determine the theoretical yield of hydrazine produced. You were given the actual yield of hydrazine produced: 25.2g. Then use the formula for percentage yield and plug in the values.
(actual yield/theoretical yield)*100 = percentage yield

hannabarlow1A
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Re: How do you approach question M1 in 6th edition book?

Postby hannabarlow1A » Wed Jun 26, 2019 8:46 pm

Since we are told hypochlorite is in excess, we know that ammonia is our limiting reactant. To find theoretical yield, first divide the 35 g of ammonia by ammonia's molar mass to convert the value to moles of ammonia. Luckily, the chemical equation is already balanced so we can see the stoichiometric ratios between all the reactants and products. Since Ammonia has a coefficient of 2 and hydrazine has a coefficient of 1, they have a 2:1 ratio. Hydrazine will have half the number of moles as ammonia. Then, use the molar mass of hydrazine to convert its number of moles to grams. This is your theoretical yield. We are given the actual yield of 25.2 grams, so we must divide this by the theoretical yield and then multiply by 100 for our final answer.


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