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Energetics and Thermodynamics

Reaction equations and mass

Please give step by step solutions and answers. 1) Write the balanced molecular equation for the reaction of calcium with molecular oxygen to form calcium oxide. 2) You start out with an empty crucible weighing 19.3350g. After adding some calcium to the crucible, the mass is now 22.1156g. After heating the calcium and co

Combustion & Mass

Limestone(CaCO3) is used to remove acidic pollutants from smokestack flue gases in a sequence of decomposition-combination reactions. The limestone is heated to form lime (CaO), which reacts with sulfur dioxide to form calcium sulfite. Assuming a 74.7% yield in the overall reaction, what mass of limestone is required to remove a

Chemistry review questions

Question 2 An imaginary element X consists of two isotopes having masses of 110.00 amu and 112.00 amu. ("amu" is an atomic mass unit.) A sample of X was found to consist of 79.94% 110X and the rest is 112X. What would be the average atomic mass of X in this sample? Give your answer to four significant figures. Do not enter a

Evaluting Melting Point Determination

1. In a mixture of approximately 20% camphor and 80% naphthalene. What would you expect the melting point to be? (+/-)camphor (175-177 Celsius) and naphthalene (80-81 Celsius). 2. Describe the expected type of error in the observed m.p. (unaffected, high, low and/or broad) when the melting point is determined as follows: a.

Entropy of mixing

I am trying to figure out how, for the entropy of mixing of two polymers, one gets from: Change in entropy of mixing (delta S sub m) = k[(N1 + N2) ln (N1 + N2) - N1 ln N1 - N2 ln N2] to the result: change in entropy of mixing (delta S sub m) = -k(N1 ln v1 + N2 ln v2) where v1 and v2 are the volume fractions of the two

What is the percent of CdSO4 by mass in a 1.0 molal aqueous solution?

1. What is the percent of CdSO4 by mass in a 1.0 molal aqueous solution? 2. Calculate the amount of heat that must be absorbed by 10.0 gram of ice at -20 C to convert it to gaseous water at 110 C. Given: Specific heat ice = 2.1 Joule/gram water = 4.184 Joule/gram steam = 1.84 Joule/

Molar enthalpy of vaporization

The normal boiling point of bromine is 58.8 C. Given that the vapor pressure pressure of methanol (sic) is 75.0 torr at 2.5 C, Calculate the molar enthalpy of vaporization of bromine. Show all work and thanks for your help and time.

Vapor Pressure Sample Question

The vapor pressure of ethanol is 400 mmHg at 63.5 C. Its molar enthalpy of vaporization is 39.3 K Joule/mol. What is the vapor pressure of ethanol, in mmHg, at 34.9 C? Show work. For iodine, the molar enthalpy of sublimation is 62.3 k Joule/mol. The molar enthalpy of fusion is 15.3 k/Joule/mol. Calculate the molar enthal

Melting and Vaporizing Substances

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

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

Metal Heating

Given that: Initial temperature of metal: 20c Final temperature of metal: 100c Initial temperature of water from calorimeter: 20c Final water temperature from calorimeter: 28c 1. What is estimate of specific heat for metal? (use 1 cal/gm°C for water) 2. What is estimate the atomic weight of metal?

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.

Heat Capacity and Calorimetry

When steam condenses to liquid water, 2.26 kj of heat is released per gram. The heat from 168g of steam is used to heat a room containing 6.44 x 10 to the 4th grams of air (20ft x 12 ft x 8 ft). The specific heat of air at normal pressure is 1.015 j/(g.C). What is the change in air temperature, assuming the heat from the stea

Calorimetry

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

Calculating enthalpy change

The bombardier beetle uses an explosive discharge as a defensive measure. The chemical reaction involved is the oxidation of hydroquinone by hydrogen peroxide to produce quinone and water. Please see the attached file for full problem description.

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

Calculating Specific Heat Capacity

A piece of chromium metal with a mass of 24.26g is heated in boiling water to 98.3C and then dropped into a coffee-cup calorimeter containing 82.3g of water at 23.3C. When thermal equilibrium is reached, the final temperature is 25.6C. Calculate the specific heat capacity of chromium. You determine that 187 J of heat is requi

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

General chemistry questions

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

Word problem - work, power, energy

Step 1: A 240 horsepower car beginning at a stop goes 1/10 of a mile. At optimum performance, what is the maximum speed in miles per hour the car can reach? Feet per minute? Step 2: How many feet have been traveled in a 240 horsepower car when the speed reaches 35 MPH at optimum performance? what fraction of a mile is that d

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

Calculate in kilograms

Elemental phosphorus is made by heating calcium phosphate with carbon and sand in an electric furnace. What quantity of calcium phosphate, in kilograms, must be used to produce 15.0kg of phosphorus? _________________________________________ kilograms

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

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