Chemical Engineering Basics Flashcards
(6 cards)
Which one of the following is incombustible ?
A. H2
B. CCl4
C. C2H2
D. S
Most inorganic compounds contain ionic bonds - atoms tightly held together in contrast to organic (carbon) compounds. This allows organic compounds to react with oxygen. Salts, inorganic compounds, do not react with oxygen, hence they are incombustable.
B. CCl4. Almost all organic liquids are considered “flammable,” meaning they are capable of catching on fire and sustaining combustion (an important exception is thathalogenated solvents tend to be non-flammable).
The softness or hardness of a grinding wheel depends upon the type & amount of bonding material used. For general purpose cutter grinding __________ grinding wheel is normally used.
A. hard
B. soft
C. silicon carbide
D. aluminium oxide
Grinding wheels contain abrasive grains and layers of fiberglass bonded into a wheel shape by another substance. The abrasive grains act as grinding tools,removing material from a workpiece to shape and refine it. Grinding wheels are useful in many grinding and machining operations.
D. Al203. Aluminum oxide or fused corundum (Al2O3) is a crystalline aluminum oxide obtained from bauxite clay containing about 60% of aluminum. It is referred to as the fused corundum due to the technology of its production in electric arc furnaces.
Aluminum oxide is the most common abrasive used in grinding wheels. It is usually the abrasive chosen for grinding carbon steel, alloy steel, high-speed steel, annealed malleable iron, wrought iron, and bronzes and similar metals while Silicon carbide is an abrasive used for grinding gray iron, chilled iron, brass, soft bronze and aluminum, as well as stone, rubber and other non-ferrous materials.
Tin based white metals are used, where bearings are subjected to
A. high pressure & load.
B. low pressure & load.
C. high temperature.
D. large surface wear.
Metal bearing is a process that is used for bearing white metals and these are fused into each other when they are molten. Ceramic material is mostly used for bearings and for high speed applications.
D. Large Surface Area. Tin based white metals are used, where bearings are subjected to large surface wear. The white metals of light colored alloys are subjected used for lead based and tine based alloys. They are soft and are very ductile.
Friction factor for fluid flow in pipe does not depend upon the
A. pipe length.
B. pipe roughness.
C. fluid density & viscosity.
D. mass flow rate of fluid.
For Laminar flow
f = 64/Re
For Turbulent flow
f = 0.316/[(Re)^(1/4)]
Re = (Fluid Density× Fluid Velocity × Pipe Diameter) ÷ (Dynamic Viscosity) = (4 × Mass Flowrate) ÷ (π × Pipe Diameter × Dynamic Viscosity)
The friction factor depends on the roughness of the pipe in case of turbulent flow.
Therefore A. Pipe Lenghts is the answer
All of the following alloying elements of steel increases hardness but sacrifice ductility, except
A. nickel
B. vanadium
C. molybdenum
D. chromium
Steelis an alloy of iron and carbon, along with small amounts of other alloying elements or residual elements as well. The plain iron-carbon alloys contain 0.002 - 2.1% by weight carbon.
Alloy steelscontain 0.1 - 1.0% carbon. Alloying materials like chromium, nickel, molybdenum, vanadium, copper, aluminium, sulphur etc. are added to improve the properties of steel.
Nickel - Increase strength and hardnesswithout sacrificing ductility and toughness. Hence, Option 1 is correct.
Vanadium - Increases strength, hardness, wear resistance and resistance to shock impact at high temperature andlowers ductility.
Molybdenum - Improves hardenability, toughnessand lowers ductility. Improves elevated temperature strength, creep resistance
Chromium - Increases hardness and lowers ductility. Improves oxidation and corrosion resistance. Corrosion resistance may also be enhanced by Ni and Mo addition.
The following type of bonding is strongly directional in solids.
a) Vander Waal’s
b) Ionic
c) Metallic
d) Covalent
There are 5 types of bonding in solids:
Ionic bonding
Covalent bonding
Metallic bonding
Hydrogen bonding
Van der Waals bonding.
Covalent bonding is the type of bonding that is strongly directional in solids. Covalent bonds provide stiffness, strength and a high melting point. The covalent bonds are directional bonds because atoms are bonded covalently and prefer specific orientations in space relative to one another. That’s why solids having covalent bonds have definite shapes.
The meaning of covalent bonds being directional is that atoms bonded covalently prefer specific orientations in space relative to one another. As a result, molecules in which atoms are bonded covalently have definite shapes.
Ionic bond is non-directional, because charge is uniform in all direction. An ion is surrounded by other ion from all the direction. But covalent and coordinate bond are formed by one side only hence are directional.
