Yttrium barium copper oxide (YBa2Cu3O7) is a famous crystalline material ever discovered in the world of quantum physics. It becomes a superconductor when it is exposed to liquid nitrogen. Calculate the mass percentage of yttrium, barium, copper, and oxygen in this compound.
Correct answer: A. Y = 13%, Ba = 41%, Cu = 29%, O = 17%
- A. Y = 13%, Ba = 41%, Cu = 29%, O = 17%
- B. Y = 17%, Ba = 39%, Cu = 23%, O = 21%
- C. Y = 15%, Ba = 52%, Cu = 10%, O = 23%
- D. Y = 19%, Ba = 41%, Cu = 31%, O = 9%
Explanation
To find the mass percentage of each element in YBa₂Cu₃O₇, we need to first calculate its molar mass, which is:1(Y) + 2(Ba) + 3(Cu) + 7(O) = 1(88.91 g/mol) + 2(137.33 g/mol) + 3(63.55 g/mol) + 7(15.99 g/mol) = 666.96 g/molNext, we calculate the mass of each element in one mole of YBa₂Cu₃O₇:- Y: 88.91 g/mol x 1/mol = 88.91 g- Ba: 137.33 g/mol x 2/mol = 274.66 g- Cu: 63.55 g/mol x 3/mol = 190.65 g- O: 15.99 g/mol x 7/mol = 111.93 gFinally, we can calculate the mass percentage of each element as:- % Y = (88.91 g / 666.96 g) x 100% = 13%- % Ba = (274.66 g / 666.96 g) x 100% = 41%- % Cu = (190.65 g / 666.96 g) x 100% = 29%- % O = (111.93 g / 666.96 g) x 100% = 17%Therefore, the correct answer is A) Y = 13%, Ba = 41%, Cu = 29%, O = 17%.
This question appeared on the NUMS 2019 (cancelled sitting) paper, which you can sit online with every answer explained.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Moles and Avogadro's Number
The mole connects the microscopic number of particles with measurable mass, using Avogadro's number, 6.022 × 10²³ particles per mole. Questions involve molar mass, conversion between mass, moles and particles, percentage composition, empirical and molecular formulas, and distinguishing atoms, molecules, ions and formula units.
Practise Fundamental Concepts of Chemistry
894 free Fundamental Concepts of Chemistry MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Chemistry questions like this
Chemistry is on 14 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Moles and Avogadro's Number questions
The mole fraction of NaCl, in a solution containing 1 mole of NaCl in 1000g of water is:
A laboratory experiment requires each student to use 10g of caustic soda (NaOH). A laboratory personnel opens a new 909g of said salt. If 42 students took exactly the required amount of salt, how much should be left in the container at the end of the experiment?
Jimmy went to a hospital to take some laboratory tests. After he had gotten the result, he found out that the count of his red blood cells was 2.7 x 10^6/uL. The doctor said that the normal adult male hemoglobin count is 13.5 g /100 mL. A low hemoglobin count would result in anemia, and a high hemoglobin count would result in polycythemia. If you were the doctor, identify the condition of Jimmy. Hemoglobin is (C2952H4664O832S8Fe4). One red blood cell has approximately 270 million hemoglobin molecules.
The number of Hydrogen molecules required to form36g of water2H, +O,->2H ,O
If N is the number of molecules of a gas in a container. The number of moles can be calculated as:
Number of molecules in one dm3 of water will be almost: