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Some good practice problems (not from HW) to study for the test!

Posted: Sat Oct 05, 2019 9:48 am
by Julia Mazzucato 4D
Hi guys, I wanted to create a thread for some good practice problems from the TB (not part of the HW questions) to study for the test in week 2. Feel free to share any good practice probs you find so we can all study together!

Empirical and Molecular Formula derivation + Mass Composition practice

Mass Composition
F.6) What is the mass percentage composition of the hormone testosterone, C19H28O2?

F.28) A mixture of KBr and K2S of mass 6.14g contains 2.50g of potassium. What is the percentage by mass of KBr in the mixture?

Empirical Formula Derivation
F.10) Cadaverine is formed in decomposing flesh. A report on the analysis of cadaverine listed the mass percentage composition as 58.77% C, 13.81% H, 27.42% N. In what atom ratios are the atoms present in cadaverine?

F.16) The compound fluoxetine is sold as the antidepressant Prozac when combined with HCL. Fluoxetine has the mass percentage composition 66.01% C, 5,87% H, 18.43% F, 4.53% N, and 5.17% O. What is the empirical formula of fluoxetine?

Molecular Formula Derivation
F.18) Mass percentage composition of Paclitaxel is 66.11% C, 6.02% H, 1.64% N, and the rest is oxygen.
What is the empirical formula of paclitaxel?
The molar mass is 853.91 g/mol. What is the molecular formula?

F.21) A 1.78 mg sample of the compound didemnin-A was analyzed and found to have the following composition: 1.11 mg C, 0.148 mg H, 0.159 mg N, and 0.363 mg O. The molar mass of didemnin-A is 942 g/mol.
What is the mass percentage composition of didemnin-A?
What is the empirical formula of didemnin-A?
What is the molecular formula of didemnin-A?

Good luck everyone!!

Re: Some good practice problems (not from HW) to study for the test!

Posted: Sat Oct 05, 2019 10:15 am
by Julia Mazzucato 4D
Answers

F.6) 79.12% C, 9.786% H, 11.09% O
F.28) 76.09%
F.10) C5H14N2
F.16) C17H18F3NO
F.18) C47H51NO14 molecular formula=empirical formula
F.21) mass comp 62.4% C, 8.31% H, 8.93% N, 20.4% O, EF= C8H13NO2, MF= C48H78N6O12