5. Water and hydrogen
(a) Hydrogen can reduce coppers Oxide but not alluminium oxide. Explain
(b) When water reacts with potassium metal the hydrogen produced ignites explosively
on the surface of water.
(i) What causes this ignition?
(ii) Write an equ
11th February 2016
The molding processes can be classified on the basis of the method. The processes are as described
1. Bench molding;
This method is normally used for small jobs. There are two flasks, the cope and the drag and a
5th February 2016
Please note that Green scripts in this document were as researched by the student with the Lecturers
instructions from the referenced material.
SAND MOULDING PROCESSES
Economic utilization requires the recovery and processing of l
25th February 2016
CLEANING OF CASTINGS:
In the cleaning process, castings are shaken in which gates, risers and cores are removed
Cleaning also involves some bits of finishing or machining. Gates and risers will be removed using the
28th January 2016
A gating system is that part of the mould cavity, through which the metal is poured and fill the
casting impression. The design of the gating system provides the means for controlling the pattern of
metal flow wit
22nd January 2016
The Rate of solidification;
In a sand mould, the rate at which a casting freezes is determined primarily by the ability of the
mould to accept heat from the casting. So if molten metal is poured against a mould, heat will flow
10th March `216
FABRICATION OF COMPOSITE MATERIALS:
The importance of composite material has grown due to the acceptance in aerospace and sporting
goods. Many manufacturing processes designed from composites are slow and labor intensive. They
18th February 2016
CORES AND CORE MAKING:
Cores are sand bars designed to form holes and cavities in casting and also to shape the outer surfaces of
cast piece. The metal usually envelopes a core on all its sides as it fills the mold cavity. Core
Indirectly acting alpha agonists
Ind: narcolepsy, appetite control, attention deficit
They have direct catecholaminergic action by
causing release of NE from nerve terminals
they inhibit MAO
They increase release of catecholami
Enduring Understanding: The brain is the control center of the
body. The numerous sections of the brain carry out specific tasks
that function in maintaining homeostasis.
Essential Questions: What are the major parts of the brain?
Introduction to Chemistry
Author: Tracy Poulsen
Supported by CK-12 Foundation
Introduction to Chem.
Authored by Tracy Poulsen
8.5" x 11.0" (21.59 x 27.94 cm)
Black & White on White paper
4. Acid Base Chemistry
4.1.1. Bronsted / Lowry Acid:
"An acid is a substance which can donate a hydrogen ion (H+) or a proton, while a
base is a substance that accepts a proton.
B- + HA <-> HB + Abase1 + acid1 <-> acid2 + base 2
26th February 2016
These are organic materials that consist of carbon chemically combined with hydrogen and oxygen
and other non-metallic substances. Plastics and synthetic rubbers are known as polymers and
polymers are composed of a larg
4th March 2016
PROCESSING OF RUBBERS AND ELASTOMERS:
Rubber and elastomers can be produced through a variety of techniques such as dipping. Dipping is
the process used for making gum-boots. It is used to produce thin parts with uniform wall
Structure of the atom and the periodic table
Na2CO3 + 2HNO3 _ 2NaNO3 (L) + CO(q) + H2O(C)
Mole ration 1 : 2
a) Moles of HNO3 in 20cm3 = 20/1000 x 0.25
= 0.005 moles
b) Moles of Na2CO3 in 25cm3 = of 0.005 moles
c) If 25cm3 = 0.0025 moles
Complete the following equation by determining the values of U and V.
(a) Distinguish between nuclear fusion and fission
(b) Compete the nuclear equation below:230
Uranium -238 disintegrate
Statement of Cash Flows
For the Year Ended December 31, 2007
Cash flows from operating activities
Cash receipts from customers.
Less cash payments:
For operating expenses.
For income taxes.
Inter-State Moving and Storage Company is setting up a control chart to monitor the proportion
of residential moves that result in written complaints due to late delivery, lost items, or damaged
items. A sample of 55 moves is selected for each of the last
Market concentration ratio is calculated by adding up the market share of largest firms in the
Mostly, four-firm concentration ratio is calculated.
It is calculated by adding the market share of 4 largest firms.
This ratio indicates whether indu
Lahey Motors specializes in selling cars to buyers with a poor credit history. Listed below is the
number of cars that were repossessed from Lahey customers because they did not meet the
payment obligations over each of the last 36 months.
1. Next year, the firm would like to increase the price of the doughnuts it sells by 6 percent.
Management forecasts that income will rise by 4 percent next year and that the price of
bagels will fall by 2 %
so due to price rise of 6%, as Ep = 2, demand w
21st January 2016
Making of mould
Design of castings/mould
Pouring of molten metal into cavity for casting
Molding processes that will include;
4th February 2016
Both synthetic and natural sands are used and the following properties are what we look for:
Silica is the main constituent but small amounts of iron-oxide, alumina, limestone and soda are
29th January 2016
Castings can be produced either in permanent moulds or expendable moulds. The use of metal
moulds is limited due to conditions imposed by repeated contact with molten metal and the cost of
3rd March 2016
Hot compression molding:
Solid granules of preformed tablets of un-polymerized plastics are introduced into an open heated
cavity, then a heated plunger is set to close the cavity and apply pressure. As the plastic melts and
The purpose of this book is to provide relevant material for each subject in O-level education here
in Tanzania. The first edition contains civics, history, geography, biology, chemistry and physics. The
content is ordered by syllabus topic a