KEN SARO-WIWA POLYTECHNIC SCHOOL OF APPLIED SCIENCES DEPARTMENT OF SCIENCE LABORATORY TECHNOLOGY FIRST SEMESTER EXA
KEN SARO-WIWA POLYTECHNIC
SCHOOL OF APPLIED SCIENCES
DEPARTMENT OF SCIENCE LABORATORY TECHNOLOGY
FIRST SEMESTER EXAMINATION, 2017/2018 ACADEMIC SESSION
COURSE CODE: STC 112
COURSE TITLE: INORGANIC CHEMISTRY
LEVEL: ND 1 TIME: ________
1(a) A Sample of pure Calcium metal weighing 1.35 grams was quantitatively converted into 1.88gms of pure calcium oxide. If the atomic mass of oxygen is 16.0, what is the atomic mass of calcium?
(b) Penicillin, the first of a now large number of antibiotics, was discovered accidentally by the Scottish bacteriologist Alexander Fleming in 1928, but we were never able to isolate it as a pure compound. This and similar antibiotics have saved millions of lives that would otherwise have been lost to infection. Penicillin F has a formula which contains 14 carbon atoms, 20 Hydrogen atoms, 2 Nitrogen atoms, 1 Sulphur atom and 4 oxygen atoms. Compute the mass percent of each element.
[C = 12; N = 14; H = 1; S = 32; O = 16].
2(a) Aluminum is a metal with a light strength to weight ratio and a high resistance to corrosion; thus it is often used for structural purposes. Compute both the numbers of moles of atoms and the number of atoms in a 10.0grams sample of aluminum.
(b) Cobalt is a metal that is added to steal to improve its resistance to corrosion. Calculate both the numbers of moles in a sample of cobalt containing 5.00 x 1020 atoms and the mass of the sample
[Avegadro NO is 6.02 x 1023 per mole; AI = 27; Co = 59].
3. Baking soda (NaHCO3 ) is often used as antacid. It neutralizes excess hydrochloric acid secreted by the stomach. Milk of magnesia, which is a aqueous suspension of magnesium hydroxides [Mg(oH)2] is also used as an antacid. Which is the more effective antacid per gram, NaHCO3 or Mg (oH)2 ? [Na = 23; H = 1; C = 12; U = 35.5; Mg = 24; O = 16].
4. Nitrogen gas can be prepared by passing gaseous ammonia over solid coper (II) oxide at high tempretures. The other products of the reaction are solid copper and water vapour. If 18.1gms of Ammonia reacted with 90.4gms of Copper (II) oxide,
- Which is the Limiting reactant?
- How many grams of nitrogen will be formed?
- If the reaction actually gave 6.63gms of Nitrogen, what is the percent yield? [N = 14; H = 1; Cu = 64; O = 16].
5(a) Formalin is an aqueous solution of formaldehyde (HCHO). At high concentration is it used as preservation of biological specimens. How many grams of formaldehyde are in 2.5L of 12.3M formalin?
(b) How many moles of Ag+ ions are present in 25ml of 0.75M AgNO3 )
6(a) Use the structure sulphur dioxide to illustrate;
(i) The bond length and (ii) Bond angle.
(b) Arrange the following bonds in the increasing order of bond polarity
N-H; H-H; O-H; CL-H; S-H; -H, giving that the values of electronegativity are [H = 21; S = 25; CL = 3.0; O = 3.5; F = 40; N = 30].
(7) When nitrogen reacts with excess Chlorine gas, a certain compound (NCL5) is formed. But in the solid state it consist of a 1:1 mixture of NCL4+ and NCL6 ions. Predict the Lewis structure of NCL5, NCL and NCL6 .