The following twenty problems are selected questions dealing with general chemistry and the chemistry of the YBCO superconductor.

Give the formula weights of the following compounds.

  1. CO(2)
  2. O(2)
  3. CuO
  4. BaCO(3)
  5. H(2)0
  6. Y(2)O(3)
  7. YBa(2)Cu(3)0(7)
  8. Bi(2)Sr(2)CaCu(2)0(8)
  9. If a student wants to make 250 grams of YBa(2)Cu(3)O(7), how many moles of each element will be needed?
  10. How many grams of each element will the student need in problem #9?
  11. When yttrium oxide, barium carbonate and copper(II) oxide are mixed, annealed and cooled in an oxygen atmosphere, a YBCO compound can be formed. Give the balanced equation for the formation of YBa(2)Cu(3)O(7). (NOTE: When BaCO(3) is heated BaCO and CO(2) are formed.)
  12. How many additional moles of O(2) need to be added to the YBCO compound formed in problem #11 to make it superconducting?
  13. Why does the YBCO material need to be cooled in a stream of oxygen gas?
  14. What color should the YBCO superconductor be after it has been annealed?
  15. What type of superconductor is the YBCO material?
  16. What is the name of the crystal structure found in YBCO ceramics?
  17. What is the critical temperature Tc for YBa(2)Cu(3)O(7)?
  18. Which atoms occupy the corners of the crystal lattice of the YBCO compound?
  19. If a YBCO superconductor is left unprotected in the air a chemical reaction can occur with CO(2) and water resulting in deoxygenation of the sample. How can you prevent this from happening?
  20. Bi(4)(Sr,Ca)(6)Cu(4)O(16) is another high temperature superconductor. Write the balance equation for the formation of Bi(4)(Sr,Ca)(6)Cu(4)O(16) from its metal oxides.

    (NOTE: the moles of Sr and Ca may vary but the total mole of Sr and Ca is equal to six).

  21. Briefly describe the formation of Cooper Pairs according to the BCS Theory.

Date posted 04/01/96 (ktb)