Explore BrainMass

Energetics and Thermodynamics

Enthalpy Change of a Reaction

Calculate the enthalpy change of a reaction using the following values, enthalpy of reactant 1 = 404 kJ, enthalpy of reactant 2 = 432 kJ, enthalpy of product 1 = 218 kJ, enthalpy of product 2 = 74 kJ and enthalpy of product 3 = 199 kJ.

Calculating the Enthalpy Change for the Reaction

Calculate the enthalpy change for the reaction, NaCl + water  NaOH + HCl. Using the given values, the sum of the enthalpies of NaCl and water = 293 kJ and the sum of the enthalpies of NaOH and HCl = 162 kJ.

Standard Enthalpy Change

Calculate the standard enthalpy change of a reaction using the total enthalpies of the reactants and the products. The total enthalpy of the reactants is -912 kJ and the total enthalpy of the products is -82 kJ.

Thermochemical Enthalpy Changes

Calculate the enthalpy change of the reaction 2CO(g) + 2NO(g)  2CO(g) +N(g) using thermochemical equations: a) 2CO(g) + O(g)  2CO(g) b) 2NO(g)  N(g) + O(g) The enthalpy of the equation a) is -566.0 kJ and the enthalpy of the equation b) is -180.6 kJ.

Finding specific heat of gold

When a 50.0-g nugget of pure gold is heated from 35.0°C to 50.0°C, it absorbed 5200.0 J of energy. Find the specific heat of gold.

Calculate the Pressure

Step by Step explanation Ferrous oxalate, FeC2O4, will decompose on heating: FeC2O4 (s) ® FeO (s) + CO2 (g) + CO (g) A 1.25-gram sample of FeC2O4 is added to an evacuated 2.00-liter steel vessel. The vessel is heated to 400°C, at which point all the FeC2O4 is decomposed. Calculate the pressure inside the vessel at 400

The gaseous hydrocarbon acetylene, C2H2 is used in welders' torches because of the large amount of heat released when acetylene burns with oxygen, producing carbon dioxide and water.

1. The gaseous hydrocarbon acetylene, C2H2 is used in welders' torches because of the large amount of heat released when acetylene burns with oxygen, producing carbon dioxide and water. First, write a balanced equation fro the combustion of acetylene is oxygen. Then, how many grams of oxygen are needed for the complete combusti

Gibbs Energy of Mixing When the Partition is Removed

Consider a container of volume 5.0 L that is divided into two compartments of equal size. In the left compartment there is nitrogen gas at 1.0 atm and 25 degrees C; in the right compartment there is hydrogen at the same Temperature and Pressure. Calculate the entropy and Gibbs energy of mixing when the partition is removed. Ass

Gibbs free energy and reaction

Given the Ka for HCLO is 3.0*10^-8, calculate delta G standard, at 25 degrees C, for : H30+(aq) + ClO-(aq) --> HCLO(aq) + H2O(l)

Free energy and entropy

For a certain complexation reaction, K=10^17. What are the signs of delta H standard, delta S standard and delta G standard for the equation from which the K expression is derived?

Gas-phase absolute entropy

1. Which molecule below should have the highest gas-phase absolute entropy at 25°C? a. CH4 b. H2 c. C2H6 d. C2H4 e. C2H2 2. Some standard entropies (at 25°C in J/mol K) are given: Ca2+(aq) -55.2, F-(aq) -9.6, CaF2(s) +68.87. ΔS° for the reaction CaF2(s)  Ca2+(aq) + 2F-(aq) at 25°C in J/K is ____

General Chemistry and Thermodynamics

7.5. Given the following table of thermodynamic data, substance ΔHf° S° POCl3 (g) -542.2 kJ/mol 325 J/mol - K POCl3 (l) -597.0 222 determine the normal boiling point (in °C) of POCl3. a. 133.0 b. 532 c. 273

General Chemistry - Law of thermodynamics

1. Which one of the following is a correct statement of the first law of thermodynamics? a. ΔS = q - T b.at absolute zero, for a pure crystalline solid, S = O c. ΔS >or equal q/T d. ΔH = ΣΔHproducts - ΣHreactants e. ΔE = q + w 2. A reversible process is one that ________. a. must be carried out at high

Lithium Iodide Solution

When lithium iodide is dissolved in water, the solution becomes hot. If an aqueous solution of LiI together with additional solid LiI were heated, would some of the solid dissolve or would more solid precipitate? I am very confused as to what this means and I can't find anything that really explains it in my book.

Enthalpy Change in a Calorimeter

You mix together the following solutions in a coffee-cup calorimeter: - 100.0 mL of 0.200 M CsOH - 50.0 mL of 0.400 M HCl Both solutions start out at 22.50°C, and the final temperature after reaction is 24.28°C. The densities of the solutions are all 1.00 g/mL, and the specific heat of the mixture is 4.2 J/g°C. Calculat

Thermodynamics and Triprotic Acid

1. Citric acid is a triprotic acid (represented by H3Cit). A student mixes together the following solutions in a styrofoam coffee cup: - 5.00 mL of 0.64 M citric acid - 45.00 mL of 0.77 M NaOH The two solutions start at a temperature of 26.0°C, and reach a final temperature of 27.9°C. The final, combined mixture has a mas

Thermodynamics and Specific Heat

You are given 10.0 grams of a mixture of NaNO3 and KF. You dissolve this mixture in 100.0 grams of water, and the temperature rises by 1.02°C. Calculate the mass of each salt in the original mixture. Assume that the specific heat of the solution is 4.18 J/g°C. Useful information: Enthalpy of solution of NaNO3: +20.5 kJ/mol

Thermodynamics and Enthalpy of Formation

I need some help with this problem, see attached file for full problem description with proper symbols: 2. a) Use only the following data to determine delta H°f for NO2 (g): - delta H°f for NO (g) is +90.4 kJ/mol - delta H = -56.6 kJ/mol for the reaction: NO (g) + 1/2 O2 (g) ---> NO2 (g) b) Find delta H for the reaction: 4


1. I need help with the standard deviation/percentage error in the attached lab experiment. 2. Also need help graphing for the ethyl acelate and unknown solvent -- plotting negative delta T versus the total volume of solute that was added (2 graphs) and calculation of the slopes 3. I am not certain but I believe this ques

P chem

Calculate deltaS standard for the sublimation of CO2. The enthalpy of sublimation is delta H^0=25.23 kJ/mol at 195K. delta S^0= 1 ATM


1. In a free radical reaction, the following step would be categorized as CH3. + Br . ----------> CH3Br a. Initiation b. Propagation c. Substitution d. Termination 2. The heat of reaction (enthalpy change, delta H) for the following reaction is I2 + CH4 -----------> CH3I + HI a. 13 kcal/mol b. 140 kca

Activation Energy of Reaction

FOR THE REACTION CO + NO2 ------>CO2 + NO The activation energy for the forward reaction is 135 kj/mol of CO reacted. A) Determine the heat of reaction. B) From the data given and the enthalpy of reaction, determine the activation energy for the reverse reaction. C) Draw and label a potentia

Vapor Density & Ideal Gas Law

Please take a look at the attached lab report on vapor density. Please see the ** items regarding percentage error and calculation of R. I can't figure out how to do the percentage error of my trials and the calculations for the R values are confusing. Thanks for your help. --- Vapor Density and the Ideal Gas Law Lab Con

Specific heat of iron

How much energy is required to heat a #10 iron nail with a mass of 7.0 g from 25.0 degrees celsius until it becomes red hot at 75? Please use degrees celsius. (specific heat of iron is .444 j/g degrees celsius)

State Functions Enthalpy

Which one is not a state function? 1. change in enthalpy 2. Work done by a system 3. (q + w) 4. Change in s (entropy) I know it is either #2 or #3, I think it is #2 but I am confused.

heat of combustion of sugar

If 10 grams of the sugar C12H22O11 burned in a calorimeter and produced a 5.5 C temperature change in 1500 grams of water, what would be the heat of combustion of 1 mole of sugar. Choices:34.5kj/m, -34.5, 1150, -1150.