EXAM 2 – Practice

“An Aggie does not lie, cheat, or steal or tolerate those who do”NameEXAM 2 Materials--(70 minutes)Signature1. Properties of polymers are a consequence of(indicate the wrong answer) [5 points]a) Type of atomsb) Arrangement of atomsc) Interactions between atomsd) Structure and bondinge) Metallic bonding2. Which of the following does not involve atomicstructure behavior of polymersa) Electronic configurationb) Number of neutrons in the atomsc) Type of bonding between atomsd) Atomic numbere) Location in the periodic table3. At room conditions, propane is a [5 points]a) gasb) solidc) liquidd) all of the abovee) none4. A polymer with the repeat unit -CH 2 -CHCl- wasmost likely polymerized froma) CH 2 =CH 2b) CH 3 -CH 3c) CH CCld) CH 2 =CHCle) CH 2 =CH 2 Cl5. Three students’ weighs are 150, 180 and 200 pounds. Find the number and weight averages?6. Assume the following point defects(a) Mg 2+ ions substitute for yttrium atoms in Y 2 O 3(b) Fe 3+ ions substitute for magnesium ions in MgO(c) Fe 2+ ions replace sodium ions in NaClIndicate for each case, what needs to be removed, added and indicate the type of point defect7. Assume there is one Schottky defect in every tenth unit cells of MgO. Calculate the density of anion vacancies8. ZnS has the zinc blende structure. If the density is 3.02 g/cm 3 and the lattice parameter is 0.59583 nm,determine the number of Schottky defects per cubic centimeter.9. For an ASTM grain size number of 8, calculate the density of grains if no magnification is used

“An Aggie does not lie, cheat, or steal or tolerate those who do”10. Determine the ASTM grain size number for this sampleMicrostructure of palladium (X200)6.00 cm x 7.40 cm11. A diffusion couple is formed between a special stainless steel and nickel. A temperature of 2500 degreesCelsius is held there for 20 hours. The initial concentration of nickel in steel is 0.40 wt%, and the surfaceconcentration is 1.00 wt%. How long will it take for the steel to reach a nickel content of 0.60 wt% at adistance of 0.6 mm into the steel? [8 points]12. You want to harden titanium by diffusion of carbon. The concentration of carbon at 1 mm into the surface ofthe titanium slab is 0.25 kg/m 3 and at 3 mm the concentration is 0.68 kg/m 3 . The temperature of thecarburizing environment is 925 degrees Celsius, and the rate at which carbon is entering the 2 mm thickregion is 1.27x10 -9 kg/(m 2 s). What is the diffusion coefficient for this treatment?13. The stress-strain diagram corresponds toan aluminum alloy cylinder that isstressed in tension where the aluminumalloy cylinder has an elastic-plastictransition. Fill in the each square withone (only one) of the following:a. Plastic deformationb. Yieldingc. Neckingd. Elastic deformatione. Fracturef. Plastic behaviorg. Modulus of elasticityh. Proportional limit

“An Aggie does not lie, cheat, or steal or tolerate those who do”14. For the next bass alloy stress-strain diagram determine the following:a. the approximate yield strength:b. the tensile strength:c. the approximate ductility, in percent elongation:d. the modulus of resilience assuming the elastic region linear: