Exercise M.1

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Amy Luu 2G
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Joined: Wed Sep 18, 2019 12:19 am

Exercise M.1

Postby Amy Luu 2G » Fri Oct 11, 2019 6:51 pm

Hydrazine, N2H4, is an oily liquid used as a rocket fuel. It can be prepared in water by oxidizing ammonia with hypochlorite ions:
2 NH3+ ClO --> N2H4+ Cl+ H2O.
When 35.0 g of ammonia reacted with an excess of hypochlorite ion, 25.2 g of hydrazine was produced. What is the percentage yield of hydrazine?

I know percent yield is actual yield/ theoretical yield so to solve this I would need to find the theoretical yield since the actual yield was given. I started by finding the molar mass of NH3. I then converted it to grams of NH3 but am unsure of what to do next.

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Re: Exercise M.1

Postby Mansi_1D » Fri Oct 11, 2019 6:58 pm

After you find the molar mass of NH3, you don't need to convert it to grams because you are looking for grams of N2H4, not NH3. So convert NH3 to moles and multiply it by the molar ratio of NH3 to N2H4 which is 2 mol of NH3 for every 1 mol N2H4 based on the equation. Multiplying this will cancel out the mol NH3 and leave you with mol N2H4 which you would convert to grams to get the theoretical yield.

Michelle Chan 1J
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Re: Exercise M.1

Postby Michelle Chan 1J » Fri Oct 11, 2019 7:00 pm

You would have to use stoichiometry. Set up a dimensional analysis to find the grams of hydrazine given 35g of ammonia. The solution to your dimensional analysis is the expected yield. Divide 25.2g (actual) by your solution (expected), then multiply by 100 to get your percent yield.

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Re: Exercise M.1

Postby CynthiaLy4F » Fri Oct 11, 2019 8:42 pm

First you divide you're 35.0 g of NH3 by the molar mass of NH3 and then use mole ratios to find the number of moles of N2H2. Then multiply the number of moles of N2H4 by its molar mass and you will get the theoretical yield of N2H4. Divide the actual yield of N2H4 by the theoretical yield and multiply it by 100 and you should get your percent yield of N2H4.

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