Organic Chemistry

SKKC 2243 –SN04   MATERIAL ENGINEERING

HOMEWORK 1

1. A sample contains 36 grams of pure water. Given NA = 6.02x1023. Determine:

a. Quantity of molecules in the sample  12.04x1023

b. Quantity of atoms in the sample 36.12 x1023

2. The quantity of hydrogen atoms in an ammonia (NH3) sample is same as the total quantity of atoms in 36 grams of water. What is the weight of the ammonia sample?

Total number of atoms in 36 g of water = (36/18) x 3 x NA = 6NA

Weight of ammonia, y

Total number of hydrogen atoms in y g of ammonia = (y/17) x 3 x NA = 6NA

3y/17 = 6

y = (6 x 17)/3 = 34g

3. A coin is made up of a copper and nickel alloy. The coin contains 0.0074 moles of Ni and 0.0886 moles of copper.

(a) What is the total mass of the coin

(b) What percentage of the mass of the coin is nickel and what percentage is copper?

[pic 1]

4. Answer the following questions based on the periodic table below:

[pic 2]

a)  Rank A, B, and C (ascending) in terms of atomic radius   C, B, A

b)  Rank A, E, and F (ascending) in terms of metallic character   A, E, F

c)  Rank A, C, and D (ascending) in terms of their electron affinity   A, D, C

d) Which element owns the properties that are in-between of those of metals and nonmetals   B

e) Consider A and its cation A+, which one is bigger in size?   A

f) Consider C and its anion C-, which one is bigger in size?   C-

g) Consider A, E and F, which element has the highest tendency to form ionic bonding with C?   F

5. The first ionization energies (IE1) of four atoms with electronic configurations (a) [He]2s2 (b) [Ne]3s1 (c) [Ar]4s1 and (d) [He]2s1 are given to be 496 KJ/mol, 419 KJ/mol, 520 KJ/mol and 899 KJ/mol. Determine which IE1 belongs to which electronic structure and explain your answer.