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Physical Chemistry

Chromate-dichromate equilibrium.

See attached file for full problem description. 1. How does the (H+) of the solution affect the CrO42-/Cr2O72- eqiuilibrium? 2. What poof was shown that CrO42- ions exist in a solution of K2Cr2O7. 3. In what way does OH- affect the equilibrium? Give two methods by which this ion upsets the equilibrium? 4. Write the e

Thermochemistry

Glauber's salt, sodium sulfate decahydrate (Na2SO4 * 10H2O) undergoes a phase transition (that is melting or freezing) at a convenient temp of 32 degrees C Na2SO4 * 1o H2O(s) yields Na2SO4 * 10 H2O(l) Change H = 74.4 kJ/mol As a result this compound is used to regulate the temperature in homes. It is placed in pl

Energy in chemical reactions

See the attached document and find the heat of reaction for each set of reactions. Reaction 1: Heat of Dissolution of NaOH Reaction 2: Heat of Reaction Between Aqueous NaOH and Aqueous HCl Reaction 3: Heat of Reaction Between Solid NaOH and Aqueous HCl Questions: 1. Write the net ionic equation for each reaction,

Buffer HEPES and MES got mixed. Identify which beaker contains HEPES.

You and a lab parnter prepare buffers to use in an experiment. Your partner prepares 200 ml 50 mM MES pH 6.0 while you prepare 200 ml of 50 mM HEPES pH 6.0. (MES and HEPES are the abbreviated names for two biological buffers often used in research labs). HEPES has MW 238.3 and pK = 7.48 MES has MW 195 and pK = 6.1 1. How

Standard free energy change for reactions

1. The Standard free energy change for the following reaction is -33.2 kJ/mol and the equilibrium constant Kp=6.59x105 at 25 C. N2(g) + 3H2 (g) <- -> 2NH3 (g) In a certain experiment, the initial pressures are P(H2)=0.25 atm, P(N2)= 0.87 atm and P(NH3)=12.9 atm. Calculate Delta G for the reaction at these pressures and pre

Chemistry Help

1. How many grams of CO2 would be formed from 20 grams of C8H10 in the following (UNBALANCED) reaction? C8H10 + O2 --> CO2 + H2O 2. How many moles of CO2 would be formed from 40 grams of CaCO3 in the following (UNBALANCED) equation? CaCO3 + HCl --> CaCl2 + CO2 + H2O 3. A gas sample has an original volume of 700 ml when

Titration of a Strong Acid

Procedure 1 (click to view assignments for this procedure) PLEASE NOTE: Titration requires several steps in order to obtain exact results. 1. Take a clean Erlenmeyer flask from the Glassware shelf and place it on the workbench. 2. Add 25 mL HCl (of unknown concentration) to the flask. 3. Add 2 drops of phenolphthal

acid base titration.

See attached file for full problem description. 13. A hydrocholoric acid solution is standardinzed by titrating 0.4541 g of primary stardard tris(hydroxymethyl)aminomethane. If 35.37 mL is required for the titration, what is the molarity of the acid? 15. A sodium hydroxide solution is standardized by titrating 0.8592 g of

Balanced & Net Ionic Equations

Write the balanced molecular equation, complete ionic and net ionic equation for the following acid base reaction. HCL(aq) + NH3(aq) NH3 is an exception, so I'm not sure what to do with it.

Salts and Their Reactions

7. When 1.00 grams of chromium metal is heated in excess iodine, 8.301 rams of chromium iodide salt is formed. Calculate the empirical formula of this salt. 8. When a calcium carbonate tablet is ingested, it dissolves by the reaction of stomach acid, which contains hydrochloric acid. The unbalanced equation for this reaction

PH, pOH, PKw

Calculating pH, POH, PKa, PKb. 37) PH 0.600 M solution of Na2S Sodium sulfide is a salt of a weak acid (hydrogen sulfide) and a strong alkali (sodium hydroxide). It therefore undergoes hydrolysis in water. Na2S = 2Na+ + S2- S2- + 2H2O = H2S + 2OH- Kh = [H2S][OH-] [S2-] [OH-] = Kh[S2-] [H2S] PO

What is the heat of combustion per gram of butane?

5. The combustion of butane produces heat according to the equation 2C4H10(g) + 13O2(g) &#61614; 8CO2(g) + 10H2O(l) &#61508;H° = -5,314 kJ What is the heat of combustion per gram of butane? A.-32.5 kJ/g B.-45.7 kJ/g C.-91.5 kJ/g D.-2,656 kJ/g E.-15,440 kJ/g 6. The freezing of water is an example of an exotherm

Calorimetry, calculations of heat energy required etc.

7. It takes 585 J of energy to raise the temperature of 125.6 g mercury from 20.0 degrees C to 53.5 degrees C. Calculate the molar heat capacity of mercury in J/(mol degrees C). 8. The specific heat capacity of silver is 0.24 J/(g x degrees C). It takes 3.57 kJ of energy to heat a sample of pure silver from 12.0 degrees C

Analytical Chemistry Questions: Ionic Strength

1. A and B react as follows: A + B = C + D. The equilibrium constant is 2.0 x 10^3. If 0.30 mol of A and 0.80 mol of B are mixed in 1 L, what are the concentrations fo A, B, C, and D after reaction? 4. The dissociation constant for hydrocyanic acid, HCN, is 7.2 x 10^-10. Calculate the percent dissociation of a 1.0 x 10^-3 M s

Empirical Formula & Products

A compound of bromine and fluorine is used to make UF6, which is an important chemical in processing and reprocessing of nuclear fuel. The compound contains 58.37% by mass of bromine. Determine its empirical formula. A) BrF B) BrF2 C) Br2F3 D) Br3F E) BrF3 Magnesium reacts with iron(III) chloride to from magnesium chlo

Argon Gas Specific Heat and Conduction Bands

3. Argon gas is composed of point atoms and oxygen gas is composed of linear molecules of the form O---O where O denotes an oxygen atom. Determine the ratio of the specific heats at constant volume for these two gases. 4. Describe two different ways by which electrons can move from the valence band to the conduction band.

Ideal Gas Law Questions

3. How is the ideal gas law modified to account for the finite volume of molecules? 4. The temperature of the sea bed 60 m below the surface and at the surface are both 20C. A rubber balloon is inflated at the sea bed with 2.0 mole gas neglecting the works done on the rubber determine: i)the volume of the balloon at the se

Gas Law

1.a) state the assumption associated with the model used to develop the Ideal Gas Law b) hence or otherwise describe under which physical conditions does the ideal gas law applies 2. Explain why hydrogen which has one electron in its lowest state, should in principle be a metallic conductor in its solid state whereas heli

Molecular Scale Mixing of Gas

A gas has a diffusion coefficient of 3*10^-5m^2s^-1. Use this information to compare how long it will take to obtain molecular scale mixing of such a gas over the following distances: i) 1*10^-4 m and ii) 10m.

Chemical: Gas-Related Problems

6. A gas operates under isothermal conditions. The initial volume of gas in the pump is 22.4 liters, the pressure is one atmosphere and temperature is 273 deg K. if 0.6 mole of gas is released and the volume remains unchanged calculate the new pressure. 7. calculate the minimum energy a photon must have to produce an electr

Buffer solution problem and problem using Henderson-Hasselbalch (H-H) equation

13. What is the pH of a solution prepared by mixing 50.00mL of 0.10 M NH3 with 25.00mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb= 1.8 x 10 -5 for NH3. 14. What is the pH of a solution made by mixing 30.00mL of 0.10M acetic acid with 30.00mL of 0.10 M KOH? Assume that the volumes of the

Weight and volume conversions to moles

How many moles are in each of the following? a. 33 g of acetylferrocene b. 10 mL of acetone c. 5 mL of water (the molecular weight of water is 18) d. 25 mL of hydrochloric acid (conc.)

Hydrogen phosphate buffer system

Please help with the following problem. Buffer solutions have the unique ability to resist changes in PH when an acid or base is added to them. One important buffer system that helps to maintain blood pH at a constant value of 7.4 is the hydrogen phosphate buffer. The chemical equation for this for this buffer system is: H2P

Reaction Mechanisms of Tin

For these reactions I need mechanisms like "with curly arrows" like I-I bonds breaking and what happens next: 1. Sn + 2I2 -> SnI4 (Ac2O,AcOH, reflux) 2. SnI4 + 2PPh3 -> (PPh3)2SnI4 (CHCl3) 3. SnI4 + (Me2SO)2 -> SnI4(Me2SO)2 (CH2Cl2)