Explore BrainMass

Physical Chemistry

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,

Molarity of Bromophenol Blue Stock

You have 20 ml of 10% Bromophenol Blue (BPB). Using a 10% stock, how would you prepare 5 ml of a 0.2 % stock? (MW BPB is 670) Assume 1 % = 1 g/100ml. In addition, what is the molarity of the 0.2% BPB Stock?

pH and Temperature

The dissociation of water increases as the temperature is raised: H20 --> H+ + OH-. If you adjust a buffer to pH 7.4 at room temperature (25 degree Celsius), then cool it down to 4 degree Celsius for an enzyme assay, will the pH increase or decrease?

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

Calculating Delta S for reaction

1. At two different temperatures, the reaction A & B is allowed to reach equilibrium and Delta H is measure. Delta H =10.9 kJ/mol for this reaction at 5.5 C and Delta H=31.0 kJ/mol at 80.1 C. Calculate Delta S for this reaction at each of these two temperatures. (Hint Delta G = 0 at equilibrium).

Predicting Reactions and Calculating Quantity

Predict whether the following reaction would proceed spontaneously as written at 298 K by calculating both Delta G and e for the reaction, given that [Co2+] =.15 M and [Fe2+]= 0.68 M. ( E1/2= -0.282 for Co2+ + 2e- -----> Co0) Co0 + Fe2+ ---> Co2+ + Fe0 A current of 0.452 A is passed through an electrolytic cell co

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

Isopentane Questions

(a) The molar volume of isopentane (C5H12) is 1.00 L at 503 K and 30.0 atm. (i) Does isopentane behave like an ideal gas? Justify your answer. (ii) Given that a = 17.0 L^2.atm/mol2 and b = 0.136L/mol calculate the pressure of isopentane as predicted by the van der waals equation. (b) The elements of group 5A, the nitro

Heat Engine, Net Work, Waste Heat

An inventor claims to have developed a heat engine that receives 750 kJ of heat from a source at 400K and produces 250 kJ of net work while rejecting the waste heat to a sink at 300K. Is this a reasonable claim? Why?

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

Solutions, Solubility and Concentration

18. The chloride in a 0.12-g sample of 95% pure MgCl2 is to be precipitated... Solutions, Solubility and Concentration. See attached file for full problem description.

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

Analysis of Calcite Sample

The analysis of a calcite sample yielded CaO percentages of 55.95, 56.00, 56.04, 56.08, and 56.23, respectively. The last value appears anomalous; should it be retained or rejected?

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)  8CO2(g) + 10H2O(l) 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