1. When 5.00 grams of sodium hydroxide dissolves in 100. grams of water the temperature rises from 25.0 oC to 38.0 oC. Is this reaction endothermic or exothermic? EXPLAIN. Calculate the value of ∆H (kJ/mol) and its sign. Draw an enthalpy graph and clearly label all parts.

Calculate ΔHrxn for the following reaction:
Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)
Use the following reactions and given ΔH′s.
2Fe(s)+3/2O2(g)→Fe2O3(s), ΔH = -824.2 kJ
CO(g)+1/2O2(g)→CO2(g), ΔH = -282.7 kJ

Biphenyl, C12H10,C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6.C6H6.

At 25 ∘C,25 ∘C, the vapor pressure of pure benzene is 100.84 Torr. What is the vapor pressure of a solution made from dissolving 17.0 g17.0 g of biphenyl in 29.9 g29.9 g of benzene?

Suppose 25.0g of potassium chloride is dissolved in 350.mL of a 0.60 M aqueous solution of ammonium sulfate. Calculate the final molarity of chloride anion in the solution. You can assume the volume of the solution doesn't change when the potassium chloride is dissolved in it. Round your answer to 3 significant digits.

Calculate the Delta H^o , Delta S^o Delta S surroundings, Delta S universe and Delta G^o for the following reaction at 25 ^oC:

2 NiS (s) + 3 O2 (g) --- > 2 SO2 (g) + 2 NIO (s)

Delta H^o = - 890.0 kJ

Delta S^o SO2 (g) = 248 J/K mol, Delta S^o NiO (s) = 38 J/K mol, Delta S^o O2 (g) = 205 J/K mol, Delta S^o NiS (s) = 53 J/K mol

1a. determine the pH of a citrate buffer that is 0.14 M citric acid (H3C6H5O7) and 0.18 M sodium citrate (NaH2C6H5O7). (What if it were 0.14 sodium citrate and 0.18 M disodium citrate (Na2HC6H5O7)?

2a. For the origional citrate buffer in question 1a, determine what the pH will be if 10mL of 1.09 M HCl solution is added to 250mL of the buffer?

3a. For the origional citrate buffer in wuestion 1a, determine how much 1.09 M HCl could beadded before you excedd the effective capacity of the buffer. (How much 1.09 M HCl would be required to get [A-]/[HA} to equal 0.1)?

A solution of household bleach contains 5.25% sodium hypochlorite, NaOCl, by mass. Assuming that the density of bleach is the same as water, calculate the volume of household bleach that should be diluted with water to make 500.0 mL of a pH = 10.00 solution. Use the K a of hypochlorous acid found in the chempendix.

It takes 150mL of 5M sodium hydroxide to neutralize 250mL of sulfuric acid. What is the concentration of the sulfuric acid?

Determine the values required to prepare 50.0 mL of a solution that buffers at a pH of 4.74.

1. Volume of 0.10 M Acetic Acid needed?

2. Volume of 0.1 M sodium Acetate needed?

3. Volume of 1.0 M Acetic Acid needed?

4. Volume of 1.0 M Sodium Acetate needed?

The “Zebra” cell was invented in 1985 in South Africa as part of the “ZEolite Battery Research Africa” project, and is used in all-electric municipal buses and other vehicles. It uses nickel and molten sodium as its electrodes. Its overall cell reaction is

NiCl₂(l) + 2Na(l) <--> Ni(s) + 2NaCl(l)

a)              Write the two half-reactions for this battery.

b)             Calculate the E^o for the Zebra cell (show your work).

c)              Are the reactants in this battery at room temperature when it is operating? Explain how you know.

How many grams of potassium chlorate decompose to potassium chloride and 932 mL of O2 at 128°C and 684 torr?

2 KClO3(s) → 2 KCl(s) + 3 O2 (g)

10. In an experiment, a sample was 90% decomposed in 24 min. Approximately how long would this decomposition have taken if the sample had been heated 20°C higher? (Hint: Assume the rate doubles for each 10°C rise in temperature.)

11. Find which kind of catalyst is necessary to facilitate the reaction between molecular nitrogen and molecular hydrogen to make ammonia (several words description)

Calculate the pH when 54.0 mL of 0.150 M KOH is mixed with 20.0 mL of 0.300 M HBrO (Ka = 2.5 × 10⁻⁹)