Please answer the question Discuss the following: a. Delta f H degree becomes le
ID: 909726 • Letter: P
Question
Please answer the question Discuss the following: a. Delta f H degree becomes less negative along the series LiF, NaF, KF, RbF, and CsF, but more negative along the series Lil, Nal, KI, Rbl, and Csl. b. Raising the temperature of a sample of alpha-Fe from 298 K to 1200 K (at one bar pressure) results in a change of coordination number of each Fe atom from 8 to 12. c. Although a non-metal, graphite is often used as an electrode material. d. The seminconducting properties of silicon are improved by adding minute amounts of boron. e. The Cr and Ni content of stainless steels used to make knife blades is different from that used in the manufacturing of spoons.Explanation / Answer
(a) Smaleer anion is more effectively attracted by the smaller cation where as larger anion forms more stable bond with larger cation.
Hence enthalpy value is less negative for fluorides as the size of cation increases down the group.
similarly enthalpy of is more negative for iodides as the cation size increases down the group.
(b) Raising the temperature expands the iron making it able to get attracted by 12 other iron atoms.
(c) Since in graphite Carbon undergoes sp2 hybridisation, each carbon contains a single electron in pure p-orbital, which makes graphite as good conductor of electricity.
(d) Semiconducting properties of silicon are improved by doping with boron, where the process forms holes through electricity is conducted.