Share
Explore BrainMass

Energetics and Thermodynamics

Melting and Vaporizing

Show the heating curve of a subtance that melts and then vaporizes. (a) Sketch the heating curve of carbon dioxide at atmospheric pressure, starting at -100 C and ending at 30 C. (b) Sketch the same heating curve as it would appear at a pressure of 10 atm. (c) Under what conditions would the heating curve resemble the on

Colligative Properties - Boiling Point and Freezing Point of Water

Show how the boiling point and freezing point of water are affected by the addition of various solutes. (a) If you were to dissolve 10 g sodium chloride in 500 g water, what would be the boiling point of the solution? (b) If you were to heat the solution in part (a), and continue heating it as it boiled, what would happen to th

Enthalpy Of Solution

Look at the dissolution of various salts. Compare the dissolution of sodium hydroxide with that of sodium chloride. a) How do the energy changes for the overall processes compare? b) Discuss the difference in magnitude of each of the three steps for dissolution of the two compounds.

Heat of formation

Methylene chloride can be prepared from the reaction of methane and chlorine, by the following equation: CH4(g) + Cl2(g) ---> CH2Cl2(g) + HCl(g) Calculate the standard heat of formation in kilojoules for the reaction using the following measured heats of formation. HCl(g) + CH3Cl(g) --> CH4(g) + Cl2(g) Delta H = +98.3 kJ CH

Entropy Change

Question: The reaction of ammonium nitrate when added to water is endothermic (H=25.7 kJ) and can be written as: NH4NO3(s) + H2(l) ---> NH4NO3(aq) a) Determine the heat of formation of NH4HO3(aq). b) What would be the final temperature of a solution that contained 50 grams of NH4NO3 dissolved in 125 mL of water. Use a spec

Hydrate Formula and Gravimetric of Cloride

1. Given that moles of water loss = Weight of water / GMW H2O (=18.051 ) and moles of CuSO4 = final weight/ GMW CuSO4 (=159.61) :Initial Weight: 116.877g (cooper II sulfate hydrate 30g + water ) :Final Weight: 19.177g (after heat compound with burner) :Weight of Water driven off (Initial weight - final weight) : 97.

Mechanisms - reversible reactions

When (1) and (2) are placed in a solution of sodium methoxide and methanol, (3) is formed. What is the structure of (3)? Provide a DETAILED mechanism for this reaction. Provide a DETAILED mechanism for the conversion of (3) to (4), carbon dioxide and acetone. In both mechanisms, indicate which reactions are reversible. Ple

Enthalpy Change for Dissolution

In a coffee-cup calorimeter, 1.10 g of NH4NO3 is mixed with 76.0 g of water at an initial temperature of 25.00°C. After dissolution of the salt, the final temperature of the calorimeter contents is 23.93°C. Assuming the solution has a heat capacity of 4.18 J/C/g and assuming no heat loss to the calorimeter, calculate the entha

Enthalpy

See attachment Consider the following reaction. CH4(g) + 2 O2(g) CO2(g) + 2 H2O(l) H = -891 kJ Calculate the enthalpy change for each of the following cases. (a) 3.00 g methane is burned in excess oxygen. (b) 3.00 103 L methane gas at 738 torr and 21°C is burned in excess

Heat capacity

A 5.00 g sample of aluminum pellets (specific heat capacity = 0.89 J/°C · g) and a 10.00 g sample of iron pellets (specific heat capacity = 0.45 J/°C · g) are heated to 100.0°C. The mixture of hot iron and aluminum is then dropped into 97.7 g of water at 24.2°C. Calculate the final temperature of the metal and water mixtur

Chemistry Problem Set: Heat Energy and Temperature

The specific heat capacity of benzene is 1.74J/g*K. What is its molar heat capacity (Jmol*K)? What quanity of heat is required to raise the temperature of 50.00mL of water from 25.52 to 28.75C? The density of water at this temperature is 0.997 g/mL. When 108g of water at a temperature of 22.5C is mixed with 65.1g of wat

Molarity/ chemical equations, shapes

23) ....CrOsub2^- + ... OH^-...CrOsub4^2- + ...Hsub2O+ e^- When the equation for the half reaction above is balanced what is the ratio of the coefficient's OH^-: CrOsub2^-? a) 1:1 b) 2:1 c) 3:1 d) 4:1 e) 5:1 24) CuO(s) + Hsub2(g) <--- / ---> Cu(s) + Hsub2O(g) triangle H = -2.0kJ The Substances in

Gas Law Problem

Nitrogen and Hydrogen gases react to form Ammonia. A closed, rigid cylinder contains a total of 0.750 mol of gas at 25 degrees C and 1.10 atm before the reaction takes place; the mole ratio of hydrogen to nitrogen in the cylinder is 3:2. Determine the temperature and pressure of the gas in the cylinder at the end of the reaction

Enthalpy of Reaction and Endothermic or Exothermic Assessment

Write the equation for the combustion of 1 mole of ethanol in oxygen and calculate the enthalpy of reaction for this change given delta Hf(CO2) = -393.7Kj/mol delta Hf(H2O) = -285.9 Kj/mol and delta Hf(C2H5OH)=-227kj/mol. I s the reaction exothermic or endothermic?

Calculating Mass of Products of a Heating a Hydrated Salt

The mass of a crucible and a hydrated salt was to be 21.477g. The mass of the crucible and the anhydrous salt was 20.070g. The mass of the crucible was 17.985 g. a) Calculate the mass of the hydrated heated b) Calculate the mass of h2o lost from the hydrate during heating c) Calculate the percent water in the hydrate

Simple Entropy

Please help with the following problems. A) Define entropy. Why is entropy considered an absolute quantity? B) For each of the pairs of substances below, choose the one expected to have the greater absolute entropy. Explain your answer. Assume 1 mol of each substance. i) Cu(s) or C(graphite) at the same temperatu

Heat Conversion of Ice to Water

A sample of water weighing 125g releases 10.0 kcal of heat as it cools from 80.5ºC to 0ºC. It then releases another 10.0 kcal of heat as it freezes at this temperature. How many kcal of heat are needed in order to convert 125g of ice at 0º to water at 80.5ºC?

Specific Heat

How much heat is released when 250.0g of copper is cooled from 100.0ºC to 20.5º? The specific heat of copper is 0.0921 cal/gºC.

Thermodynamic Data and Standard Enthalpy of Decomposition

Use thermodynamic data to calculate the standard enthalpy of decomposition of liquid hydrogen peroxide into water and oxygen gas: H2O2(l)-->H2O(g) + 1/2 O2(g). Calculate the energy released by the decomposition of 1.0 g of 90% hydrogen peroxide solution. Molar mass of hydrogen peroxide = 34.0 g/mol. Estimate the final temperat

Calculating the entropy of argon

The experimental specific heat capacity of argon is 0.5213 J/g/K at a pressure of 1 atmosphere at 300 K. Argon's entropy at 300 K is 3.877 J/g/K. Use these data to calculate the entropy of argon at 500 K.