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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Autumn Examinations 2012
Module Title: Engineering Chemistry (CA)
Module Code: CHEM
School: Building and Civil Engineering
Programme Title: BEng (Honours) in Structural Engineering
BEng (Hons) Common Entry
Programme Code: CSTRU_8_Y
EOMNI_8_Y
External Examiner(s): Dr Mark G. Richardson
Mr John O’Mahony
Internal Examiner(s): Ian O’Sullivan
Instructions: Part A: Answer 3 out of 5 questions.
Each question is worth 18 Marks.
Part B: Answer 12 questions. Each question is worth 2 Marks.
Duration: 2 hours
Sitting: Autumn 2012
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
PART A
Answer 3 out of 5 Questions
Each question is worth 18 Marks
Q
a) What is the individual oxidation state of chromium in dichromate, Cr 2 O 7 -2?
b) In the half-reaction 8H+^ + MnO 4 -^ Mn+2^ + 4H 2 O, what is the missing ‘ingredient’ and where does it belong in the equation?
c) Balance the following REDOX reaction; MnO 4 -^ + NO 2 - Mn+2^ + NO 3 -
Q
a) What is the molarity of a hydrochloric acid solution, if 15.78 mL of the acid is needed to completely neutralize 10.00 mL of a 0.2000 M NaOH solution?
b) An aqueous solution of 2.5 × 10-4^ M NaOH would have what hydrogen ion concentration?
c) Consider the following gaseous equilibrium at 400°C in a 2.00 L closed flask. Calculate the equilibrium constant Keq for the system at 400°C if, at equilibrium, there are 0.600 moles of ammonia, 1.20 moles of nitrogen, and 1.34 moles of hydrogen. The balanced equation for the reaction is as follows N 2 (g) + 3H 2 (g) ↔ 2NH 3 (g) + 92 kJ
Q
a) For the equation given, how many grams of hydrogen are needed to react with 70.0 g of nitrogen? N 2 (g) + 3H 2 (g) 2NH 3 (g) + 92 kJ
b) If 10.0 g of calcium hydroxide were reacted with 30.0 mL of 6.00 M HCl, according to the equation given, how much water is formed? Ca(OH) 2 (s) + 2HCl(aq) CaCl 2 (aq) + 2H 2 O(l)
c) A chemist reacts 50.0 grams of aluminum metal with 150.0 grams of chlorine gas according to the un-balanced chemical equation below. She recovers 175.0 grams of aluminum chloride product. What is her percent yield? Al + Cl 2 AlCl 3
PART B
Answer 12 questions
Each question is worth 2 Marks
- What is oxidized in the following reaction?
MnO 4 -^ + 5Fe+2^ + 8H+^ Mn+2^ + 5Fe+3^ + 4H 2 O
- In an electroplating process, describe what happens to the object to be plated with metal.
- When the pH of a solution changes from 6 to 3, the solutions acidity changes by what order of magnitude? Given that pH = -log[H+]
- In a solution of pH = 6.0, what is the [H+]
- Use LeChâtelier's Principle to predict the shift that occurs when the fluorine concentration is decreased for the following system at equilibrium. Assume all other factors remain constant.
2B(s) + 3F 2 (g)↔ 2BF 3 (g) + 45kJ
- A reaction has an equilibrium constant K equal to 1.0 × 10-5^ at a certain temperature. What can be said about the ‘position’ of equilibrium?
- For the given reaction, we start with 5.50 moles of aluminum and 10.0 moles of chlorine. How many moles of chlorine will be left over at the end of the reaction? 2Al(s) + 3Cl 2 (l) 2AlCl 3 (s)
- The metabolism of glucose or blood sugar, C 6 H 12 O 6 , a key metabolic pathway, provides 2540kJ of energy per mole of glucose. How much heat would be evolved by the metabolism of 36.0g of glucose?
- What is the % by mass of chromium in Na 2 CrO 4
- What is the molecular weight of alum, KAl(SO 4 ) 2 .12H 2 O?
- A certain nonmetal atom has 74 neutrons and a mass number of 127. Which element is this?
- How many hydrogen atoms are there in 0.5 mole of (NH 4 ) 3 PO 4?
- How many molecules of water are present in 100.0 g of water?
- What is the total maximum number of electrons that can be held in the first four energy levels?
- Scandium has which electron configuration? Hint: Use Figure Q
Figure Q
