HW problems:

1)

Give the net ionic equation for the reaction that occurs when aqueous solutions of lithium

carbonate and barium nitrate are mixed.

2)

Which of the following solutions will have the highest concentration of chloride ions? 0.10 M NaCl, 0.10 M MgCl2, 0.10 M AlCl3, 0.05 M CaCl2, 0.05 M AlCl3, 0.15 M NaCl

3)

What mass (in grams) of NH3 must be dissolved in 650.0 g of methanol to make a 0.250 m

solution?

4)

How many kJ of energy are required to transform 30.00 moles of solid benzene at -20.00 °C to

gaseous benzene at 140.0 °C?

A solution is formed by adding 3.60 grams of solid barium cyanide, Ba(CN)₂, to 250.0 ml of 0.170M sodium cyanide, NaCN. Calculate the pH of the resulting solution. You may assume that the barium cyanide dissolve completely and that the change in volume is negligible with the addition of the solid.

The concentration of an unknown must be in the range of the known concentrations. You sometimes must dilute an unknown so that the concentration is lower than thehighest concentration measured for your standard curve.

a. If you dilute 1mL of an unknown solution with 1 mL of water, the dilutedconcentration would be 1mL in a total of 2mL of solution. How would this affect the concentration? What is the dilution factor?

b. One would then have to reverse this process when reporting the original concentrationof the unknown solution. What factor would be used to calculate the originalconcentration?

c. If 1mL of unknown solution was diluted to 10mL final volume, what is the dilutionfactor? How would one calculate the original concentration?

d. If 2 mL of unknown solution was diluted to 5mL final volume, what is the dilutionfactor? How would one calculate the original concentration?

How much energy in kJ is required to fully vaporize (at temperature of boiling point = 2525C) a 270g sample of Al(s), initially at 25C?

(Enthalpy of vap = 300. kJ/mol, enthalpy of fusion = 11. kJ/mol)

(specific heat of aluminum for both solid and liquid form = 0.9 J/(K * g))

(temperature of melting point = 625C, temp of boiling point = 2525C)

1.gives the correct order for atomic radius for Mg, Na, P, Si and Ar?

2.Which one of the following elements is the most metallic? a.Ar b.K c.Mg d.Al e,Na

3.A gas mixture of Ne and Ar has a total pressure of 4.00 bar and contains 16.0 mol of gas. If the partial pressure of Ne is 2.75 bar, how many moles of Ar are in the mixture?

4.Which statements about viscosity are generally true?

(i) Viscosity increases as temperature decreases.

(ii) Viscosity increases in a series of related compounds as molecular mass increases.

(iii) Viscosity increases as intermolecular forces increase.

5.The standard cell potential (E°_cell) of the reaction below is -0.55 V. What is ΔG° (kJ/mol) for the reaction?

I₂(s) + 2 Br^-(aq) → 2 I^-(aq) + Br₂(l)

The initial steps in polymerization to form Prussian Blue is a photo-initiated reduction of Fe(III) to Fe(II).

i. This is a charge-transfer transition – what kind of charge transfer transition is it, and what is oxidized?  

ii. A gas is released as the photo-sensitized mixture is irradiated. What is it?

iii. Why does reduction of the Fe(III) center make the complex more labile? Explain in terms of CFSE.

Lycopene and beta carotene are important antioxidants found in some fruits and vegetables. Suppose an organic solvent was going to be used to extract and measure lycopene from a new hybrid tomato. A sample of aqueous tomato paste was introduced into a separatory funnel. Then an organic solvent was added. The funnel contents were swirled for several minutes. After extraction, the concentration of lycopene in the organic solvent was found to be 6.5 x 10^-4M while the aqueous phase maintained a concentration of 1.5 x 10^-5. What is the value of the partition ratio (K_D) with this extraction?

Using the value of K_D from "A", what fraction of lycopene would be extracted from the aqueous tomato paste into the organic phase if you began with 100.0 mL of tomato paste and added 50.0 mL of the organic solvent?

A visible light spectrophotometric determination of penicillin makes use of color-forming reaction of the penicillin. If this compound absorbs at 475 nm with an ε = 1560 M^-1cm^-1, what would be calculated as the limit of detection with an instrument, using a 1.00 cm cuvette, with its smallest absorbance measurement at 0.005?

An ideal gas (which is is a hypothetical gas that conforms to the laws governing gas behavior) confined to a container with a massless piston at the top. (Figure 2) A massless wire is attached to the piston. When an external pressure of 2.00 atm is applied to the wire, the gas compresses from 6.40 to 3.20 LL . When the external pressure is increased to 2.50 atmatm, the gas further compresses from 3.20 to 2.56 LL .

In a separate experiment with the same initial conditions, a pressure of 2.50 atm was applied to the ideal gas, decreasing its volume from 6.40 to 2.56 LL in one step.

If the final temperature was the same for both processes, what is the difference between q for the two-step process and q for the one-step process in joules?

Express your answer with the appropriate units.

A buffer solution contains 0.424 M ammonium chloride and 0.235 M ammonia.  

If 0.0297 moles of potassium hydroxide are added to 225 mL of this buffer, what is the pH of the resulting solution ?  
(Assume that the volume change does not change upon adding potassium hydroxide)

pH =

A buffer solution contains 0.382 M nitrous acid and 0.466 M potassium nitrite.  

If 0.0176 moles of hydrobromic acid are added to 150. mL of this buffer, what is the pH of the resulting solution ?  
(Assume that the volume change does not change upon adding hydrobromic acid)

pH =

A buffer solution contains 0.463 M KH₂PO₄ and 0.305 M Na₂HPO₄.  

If 0.0180 moles of sodium hydroxide are added to 150. mL of this buffer, what is the pH of the resulting solution ?  
(Assume that the volume does not change upon adding sodium hydroxide)

pH =

The equilibrium constant, K_c, for the following reaction is 1.80×10^-2 at 698 K.

2HI(g) -->H₂(g) + I₂(g)

Calculate the equilibrium concentrations of reactant and products when 0.257 moles of HI are introduced into a 1.00 L vessel at 698 K.

The equilibrium constant, K_c, for the following reaction is 83.3 at 500 K.

PCl₃(g) + Cl₂(g) -->PCl₅(g)

Calculate the equilibrium concentrations of reactant and products when 0.420 moles of PCl₃ and 0.420 moles of Cl₂ are introduced into a 1.00 L vessel at 500 K.