Complete the following passage with the best answers.  Some answers may be used more than once, some may not be used.   The strength and concentration of acids and bases can be measured in multiple ways.  Perhaps the simplest, oldest, and most common methods involve the use of pH 1)____________________, which change color in the presence of acid or base.  One type is called 2)____________________ paper, which generally changes to blue in the presence of base, and pink (or red) in the presence of acid.  Another type, which goes by the generic name of 3)_________________________ uses several different compounds which change color at different pH values, generating a spectrum of different colors and allowing a more accurate estimate of the pH of the solution.  For even more precise results, a digital 4)________________________ can be used, which is an electronic instrument with an electrode that is immersed in the solution to give a digital readout of pH.  Such instruments do require frequent calibration, however.  A different sort of measure involves an actual stoichometric experiment — in a 5)_______________________, a solution with a very precisely known concentration is reacted with the unknown acid or base until the exact point of complete reaction is reached, at which point the volume and concentration are used to calculate the concentration of the unknown.  In such an experiment, a common visual indicator known as 6)________________________ can be used, which changes color from clear to a purple-pink color very close to neutral pH, with the pink color seen in the basic pH range and clear when the solution is acidic.

A unit is manufacturing synthetic oil and using a hydrogenator to reduce olefin content in the product.  The hydrogenator uses compressed hydrogen and a catalyst to react with any remaining olefins (alkenes) in the material to make a saturated, more stable product.  Under current operating conditions, moles of hydrogen are required per ton of process material passing through the hydrogenator, and the unit produces tons per hour, 24 hours per day, 7 days per week.  The hydrogenator is fed by a hydrogen storage tank holding liters of hydrogen, currently at psi, with the ambient temperature stable at °C.  If an operator has just come in for a seven day shift, what should he expect the pressure reading to be on the last day of his shift (seven whole days later)?  Give your numerical answer in psi. (Note:  1 atm = 14.696 psi)

Which of the following are depictions of resonance structures?  Choose all that apply.  Note — these structures follow skeletal structure rules, and omit explicitly labelled carbons, most hydrogens, and lone pairs of electrons.  Assume normal valences and that all structures are drawn correctly, including formal charges, and that lone pair are present if they are appropriate.

Which of the following molecules have a net dipole moment?  Choose all that apply.

Match each atom from the following Lewis structure of the nitrate ion with its correct formal charge.  Do not consider any resonance structures or resonance effects, just the structure pictured.  Some answers may be used more than once, some may not be used. nitrate_FC.png 

Complete the following passage with the best answers.  Some answers may be used more than once, some answers may not be used. Bond 1)___________________ is an uneven distribution of electronic charge along a covalent bond, which results from electrons being unevenly shared as a result of differences in attraction to each atom of the bond.  This difference in attraction is the result of differences in 2)______________________, an idea proposed by Linus Pauling, which says that even formally charge-neutral atoms may attract electrons more strongly than others as a result of differences in atomic size and the the atom’s valence shell energy level.  In this way, such bonds may be ‘in-between’ the more idealized fully ionic and covalent sorts of bonds.  The polarization of such bonds can be expressed with either 3)________________ notation, which is a way of expressing a partial positive or negative charge on the bonded atoms, or 4)_________________ notation, which ‘points’ from the more-positive to the more-negative of the atoms in the bond.  The presence of such bonds may or may not render a molecule overall to show a similar charge-imbalance, known as a 5)__________________, depending on the geometry of the molecule and the way that individual bond polarizations add together.

A unit uses brine (a saturated salt (NaCl) solution) in an extraction purification of crude product coming from a reactor.  The brine storage tank has a full capacity of lbs.  If the brine solution is % m/m (mass percent), how much NaCl is in the tank when full?  Give your answer in lbs (no units, just the number) 

Choose the best answer to fill in the blanks of the passage.  Some answers may be used more than once, some may not be used. 1)__________________________ allows the determination of a quantity of a product or reactant in a chemical reaction equation on the basis of a given quantity of a different product or reactant.  In such a calculation, a mass can be converted to a(n) 2)_________________ by division by the molecular weight of the compound, then the ratio to a different compound involved in the reaction determined using the coefficients of the reaction equation.  However, in some cases one reagent may be a(n) 3)________________, such that there will not be enough of this material for the other reagents to completely react.  In such a case, the other reagents will be 4)______________________, and there will be some left over once the reaction is complete.

For each group of elements, give the preferred ionization (charge) state when ionized.  Some answers may be used more than once, some may not be used.

The complete combustion of methane has a reaction enthalpy of -861.3 kJ/mol, according to the following equation: CH4(g)  +  2 O2(g)  –>  CO2(g)  +  2 H2O(l)     ΔHrxn = -861.3 kJ/mol Calculate the enthalpy for the combustion of grams of methane.  Give your answer in kJ, and be careful of the sign and significant figures.