Dce0016:Chemistry Question Paper
Dce0016:Chemistry
Course:Diploma In Civil Engineering
Institution: Meru University Of Science And Technology question papers
Exam Year:2013
(a) Protons and neutrons don’t in fact have exactly the same mass of exactly 1 on the
carbon – 12 scale; electrons are considered absurdst mass less. Illustrate, using an
electrical field the behaviour of a beam of these particles if they are moving at the same
speed. (3 Marks)
(b) There are three types of hydrogen atoms, 1H, 2H, 3H. State their group name, explain the
difference among them. (3 Marks)
(c) What are orbitals, and how are they different from orbits? Draw a distribution density
map of 2p orbitals. (4 Marks)
(d) Illustrate polar covalent bonding using Lewis structures for Carbon and Oxygen atoms.
(2 Marks)
(e) Beginning with temperature of water of -10°?? and pressure of 5 atmospheres, draw a
pressure – temperature phase diagram for water. (3 Marks)
QUESTION TWO – (15 MARKS)
(a) Write the electronic configuration for the following elements: Ar and Cu. (4 Marks)
(b) Determine the mass in grams of the following
(i) 3.00 × 1020??2 molecules (2 Marks)
(ii) 2.00 × 10-15Mol ??2 (2 Marks)
2
(c) Determine the empirical formula of the compound with the following percent
composition. 58.53%C, 4.09%H, 11.38%N, 25.99%O (3 Marks)
(d) Write the subshell notation and the number of orbitals having theses quantum numbers in
an atom.
(i) n = 4, l = 2
(ii) n = 1, l = 0 (4 Marks)
SECTION B – 30 MARKS
QUESTION THREE – (15 MARKS)
(a) Explain the following terms
(i) Valence electrons (2 Marks)
(ii) Ionic bond (2 Marks)
(iii)Alkaline earth metals (2 Marks)
(b) Boron (B;Z=5) has two naturally occurring isotopes. Calculate the percentage
abundances of 10B and 11B from the following data. Atomic mass of B = 10.81 amu,
isotopic mass of 10B = 10.0129 amu, isotopic mass of 11B = 11.093 amu.
(4 Marks)
(c) A mass of 30.0g of oxygen reacts with 6.02214 x 1023 atoms of carbon.
(i) What is the molar ratio of Carbon to Oxygen in the products? (2 Marks)
(ii) Given that mass is conserved in a chemical reaction, what is the mass of the
product produced? (2 Marks)
(iii)Is the product Carbon monoxide, CO, or Carbon Dioxide, CO2? (1 Mark)
QUESTION FOUR – (15 MARKS)
(a) State the ideal gas law, and write its formula. (2 Marks)
(b) What is the effect of increasing the concentration of A in the following reaction
according to Le Chatitier’s principle?
????(??) + ????(??) ? ????(??) (2 Marks)
(c) Because of the key role of activation energy is deciding whether a collision of two or
more molecules will result in a reaction, it is useful to know what sort of proportion of
the particles present have high enough energies to react when they collide. For gases
these can be shown on a graph called the Maxwell-Boltzmann distribution. Draw and
label the graph. (5 Marks)
(d) Explain the following terms
(i) Indicators (2 Marks)
(ii) Strong and weak acids. (2 Marks)
(e) Write the equilibrium constant (Kw) for the following reaction. (2 Marks)
2H2O(l) ? H3O+(aq) + OH-(aq)
3
QUESTION FIVE – (15 MARKS)
(a) State the law of conservation of energy (2 Marks)
(b) You are given the following two reactions (Reaction 1 and 2);
(i) ??2??2(??) +
5
2
??2(??) ? 2????2(??) + ??2?? ?? ??? = -1299????
(ii) ??6??6(??) +
15
2
??2(??) ? 6????2(??) + 3??2??(??) ??? = -3267????
Find ??? for the following reaction (Reaction 3) and tell whether it is exothermic or
endothermic
(iii) 3??2??2(??) ? ??6??6(??) (4 Marks)
(c) Define the following terms:
(i) Electrolyte (2 Marks)
(ii) Electrolysis (2 Marks)
(iii)Galvanic cell (2 Marks)
(d) Write the Ksp expressions (solubility constant) for the following:
(i) ???? (????)2(???? ) ? ????(???? )
2+ + 2????(???? )
- (1½ Marks)
(ii) ????????3(??) ? ??????(??) + ????2(???? ) (1½ Marks)
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