Energetics Questions and Answers

Assume all the reactions below occur isothermally and isobarically and all the reactants and products are in gaseous phase In which of those reactions the process would also be isovolumetric Your answer O Cathe CH O CH OH 60 20 30 1 300 CO 200 co SH O 21 0 3H 0

The rate constant for the reaction is 0.260 M-¹. s-¹ at 200 °C. A → products If the initial concentration of A is 0.00140 M, what will be the concentration after 605 s?

We have a bomb calorimeter with a heat capacity of 555 J/K. In this bomb calorimeter, we place 1000.0 mL of water. We burn 2.396 g of a solid in this bomb calorimeter. The temperature of the bomb calorimeter and the water increases by 2.12 °C. The molar mass of the solid is 553.0 g/mol. How much heat (in kJ) will be released if we were to burn 0.148 mol of this same solid in the bomb calorimeter? Keep in mind that we want to find the amout of heat released. The specific heat capacity or water is 4.184 J/K/g. Approximate the density of water as being exactly 1.00 g/mL.

Dietheyl ether has a vapor pressure of 0.991 torr at -73.9℃. The heat of vaporization is Δvap = 34.0 kJ/mol What is the vapor pressure at 9.4 C in torr? Do not write unit in answer. Report your answer as a whole number.

The heat of fusion for sodium (Na) is 2.6 kJ/mol. How much heat is needed to melt 46 grams of Na at its melting point of 98 °C? 1.3 kJ 5.2 kJ 49.0 kJ 19 kJ

Which process is accompanied by an increase in the entropy of the system? the condensation of water on cold surface the freezing of a popsicle solid gold melting sewing a quilt a cup of coffee cooling in a mug

All liquids evaporate to a certain extent. The pressure exerted by the gas phase in equilibrium with the liquid is called vapor pressure, Pvap. The vapor pressure of a particular substance is determined by the strength of the intermolecular forces. But for any given substance, the vapor pressure only changes with temperature. The Clausius-Clapeyron equation expresses the relationship between vapor pressure and temperature: AHvap In P₂ = In P₁ + (H) (#) R where P2 and P₁ are the vapor pressures that correspond to temperatures T2 and T₁, respectively, A Hvap is the molar heat of vaporization, and R= 8.3145 J/(mol. K) is the gas constant. The vapor pressure of dichloromethane, CH₂Cl2, at 0 °C is 134 mmHg. The normal boiling point of dichloromethane is 40. C. Calculate its molar heat of vaporization. Express your answer to three significant figures and include the appropriate units.

A styrofoam calorimeter contains 70.0 mL of 2.50 M NaOH at 20.3°C. When 10.28 g H2C2O4 is added to the calorimeter, the temperature of the resulting solution increases to a maximum of 44.7°C. The reaction that occurs is: H₂C2O4(s) + 2 NaOH(aq) → Na2C₂O4 (aq) + 2 H₂O(l) What is the (experimental) enthalpy change for this reaction, ΔH ? (Use the total mass of solution and 4.18 J/(g°C) for the specific heat of the solution in your calculations.)

Rashaun adds a white crystalline solid to water in a beaker. When he picks up the beaker, he observes it feels cold to the touch. If we define the white crystalline solid and the water as the system and the beaker and Rashaun's hand as the surroundings, then heat flows from the _ to the _ The process that occurs between the white crystalline solid and the water is If no work is done during this process, the change in internal energy, ΔE, is _ and the internal energy of the system _.

Given: H₂(g) + Br₂(1)→ 2 HBr(g) ΔHx= -72.8 kJ Calculate the amount of energy absorbed or released when 15.0 g of HBr(g) is formed. 4.85 kJ absorbed 6.75 kJ released 13.5 kJ released 607 kJ absorbed

If 1.17 g of glucose are burned in a bomb calorimeter, the temperature of the 900. g of water in the calorimeter increases from 15.90 °C to 20.20 °C. If the heat capacity of the calorimeter is 460. J/oC what is the value of q for the combustion of the glucose sample? • Use Cwater = 4.184 J/gC • Report your answer using three significant figures.

A chemist fills a reaction vessel with 8.15 atm nitrogen monoxide (NO) gas, 4.02 atm chlorine (Cl₂) gas, and 6.09 atm nitrosyl chloride (NOCI) gas at a temperature of 25.0°C. Under these conditions, calculate the reaction free energy ΔG for the following chemical reaction: 2NO(g) + Cl₂ (g) <--> 2NOCI(g) Use the thermodynamic information in the ALEKS Data tab. Round your answer to the nearest kilojoule.

Describe the phase and temperature changes that will occur if you heat 50.0 g of Compound X in its solid state at -8°C until it all vaporizes. You may draw a diagram or graph if it helps answer the question. Calculate the amount of heat needed for each step of the process you described in part 1, and then calculate the total amount of heat required.

In the reaction of aluminum and iron(III) oxide to form iron and aluminum oxide, ΔH is -850 kJ. How many kJ are released when 10. g of Al react? 2 Al(s) + Fe₂O3 (s) → 2 Fe (s) + Al₂O3 (s) ΔH= -850 kJ -1100 kJ -320 kJ -160 kJ -850 kJ

Calculate the energy (J) change (ΔE) associated with an electron transition from n=2 to n = 7 in a Bohr hydrogen atom. A) 5.01 x 10-19 J B) 3.21 x 10-18 J C) 4.23 x 10-17 J D) 5.46 x 10-16 J E) 6.38 x 10-15 J

The following information is given for manganese at 1 atm: Tb = 2095.00°C Tm = 1244.00°C Specific heat solid = 0.4770 J/g °C Specific heat liquid = 0.8370 J/g °C ΔHvap (2095.00°C) = 4.090 × 10³ J/g ΔH fus fus (1244.00°C) = 266.5 J/g A 44.00 g sample of solid manganese is initially at 1219.00°C. If the sample is heated at constant pressure (P = 1 atm), _ kJ of heat are needed to raise the temperature of the sample to 1340.00°C.

In a calorimetry experiment, 0.1277 g of Mg ribbon was added to 200.0 mL 0.500 M HCl at 24.12 °C. The water temperature increased to 27.10 °C. Calculate AH per mole of HCI. (ans: -24.9 kJ/mol HCI)

Photosynthesis, the reaction plants use to make glucose, is an endothermic reaction. The reaction is shown below. Which statement best describes the energy of the products and reactants in the photosynthesis reaction? 6CO₂ + 6H₂O → C6H12O6 + 6O₂ Energy is given off during the reaction, making the energy of the products greater than the energy of the reactants. Energy is given off during the reaction, making the energy of the reactants greater than the energy of the products. Energy is absorbed during the reaction, making the energy of the reactants greater than the energy of the products. Energy is absorbed during the reaction, making the energy of the products greater than the energy of the reactants.

Given: H₂(g) + Br₂(g) = 2HBr(g) and ΔH° = 39.3 kJ/mol ΔS° = 92.4 J/mol-K. A closed container in which has initial partial pressures of PH₂ = PBr₂ = 0.200 atm and PHBr = 0.600 atm is heated to 350. °C at constant pressure (not at equilibrium). After equilibrium is attained at that temperature, what is the equilibrium pressure of HBr in atm? Assume ΔH and ΔS are temperature independent. Just put in the numerical value. The assumption is the partial pressure of HBrr at equilibrium is in atmospheres.

If 8.00 g ammonium nitrate is dissolved in 1.0 L water, the water decreases in temperature from 21.0 °C to 20.39 °C. Determine the molar heat of solution of the ammonium nitrate. (ans.: +26 kJ/mol NH4NO3)

Which of the following equations brings a decrease in entropy? In 2 CO3 (aq) + 2HCI (aq)→2NaCl (aq) + H2O(l) + C2 (g) NH4Cl (s)+ CaO(s) →12 NH3(g) + CaCl₂(s) + H₂O(l) CO2(g) + CaO(s) → CaCO3(s) 4NH 3 (g) + O2 (g)→ 2N2(g) + 6H2O(g)

Consider the two molecules, Hexane and cyclohexane below. Which of these has the smallest absolute entropy and why? H- HHHHHH -C-C-C-C-H HHH Hexane because it has a smaller number of microstates. H Hexane because it has a larger number of microstates. Hexane HH Cyclohexane OCyclohexane because it has a smaller number of microstates. O Cyclohexane because it has a larger number of microstates. H C-H &

14. Carbon, oxygen and water can combined to produce formic acid. Using Hess' law and the three thermochemical equations, calculate the AH of reaction for this reaction. (10 points) 2C(s) + O2(g) + 2H₂O(l) → 2 H₂CO2(e) - Data C(s) + O2(g) H2CO2(e)→ H₂CO2(g) CO(g) + H2O(0) → H2COz(g) → CO(g) Sheen AH = AH rxn = -110.5 kJ AH rxn = +62.9 kJ AH rxn = +33.7 kJ

4 points Calculate the lattice energy of lithium chloride from the following data: lonization energy of Li(g): Electron affinity of Cl(g): Enthalpy of formation of LiCl(s): Enthalpy of sublimation of Li: Bond energy of Cl₂(g): -733 kJ/mol -861 kJ/mol -418 kJ/mol -515 kJ/mol Li(g) → Li*(g) + 1e CI(g) +1e→Cl`(g) Li(s) + 1/2 Cl₂(g) → LiCl(s) Li(s)→→Li(g) Cl₂(g) →2Cl(g) -708 kJ/mol IE₁ = 520 kJ/mol EA=-349 kJ/mol AH = -409 kJ/mol AHsub= 159 kJ/mol AHBE 244 kJ/mol =

3. Consider the following reaction: 4 NO2(g) + O2(g) +2 N₂O5(g). a) At 298 K, the value for Keq is 7.2x1020. What is AG, in kJ/mol? b) If K = 8 at 175°C, what is AH at 25°C, in kJ/mol? c) Calculate AS, at 298 K. d) What is the value for K at 225°C?

Given the following data, calculate A, Hº for the reaction: N₂O(g) + NO₂(g) 3 NO(g) N₂(g) + O₂(g)-->2 NO(g) ΔH+180.7 kJ/mol 2 NO(g) + O₂(g) --> 2 NO₂(g) ΔH = -113.1 kJ/mol 2 N₂O(g) -->2 N₂(g) + O₂(g) ΔH-163.2 kJ/mol in kJ/mol

In this experiment, if the amount of heat absorbed by the calorimeter is 46 J and the amount of heat absorbed by the solution is 7,983.5 J, the reaction generated 0.195 moles of water. Calculate the enthalpy of reaction (in kJ/mol) of the reaction. (Answer to 2 decimal places)

A vessel contains 8.3 g of helium gas (molar mass = 4.003 g/mol) and 5.7 g of neon gas (molar mass = 20.180 g/mol) has a total pressure of 101 kPa at 25°C. What the partial pressure (in kPa) of helium gas? (Answer to 1 decimal place) Type your answer...

(Heat transfer) The specific heat for aluminum is c = 0.900 J/g°C. What mass of aluminum is required to cause a heat transfer of 1800 Joules if the temperature change is 71°C? Express your answer in gram with two decimal places. Only the numerical value will be graded.

Given the following two reactions: (1)Ba(s) + Cl₂(g) →BaCl₂(s) AH(1) = -858.6 kJ (2)Mg(s) + Cl₂(g) →→→MgCl₂(s) AH(2) = -641.3 kJ calculate the enthalpy change for the following reaction: (3) BaCl₂(s) + Mg(s) Ba(s) + MgCl₂(s) AH(3) = kJ

A student determines the heat of dissolution of solid potassium sulfate using a coffee-cup calorimeter of negligible heat capacity. When 8.42 g of K₂SO4(s) is dissolved in 119.00 g of water, the temperature of the solution drops from 25.00 to 22.63 °C. Based on the student's observation, calculate the enthalpy of dissolution of K₂SO4(s) in kJ/mol. Assume the specific heat of the solution is 4.184 J/gºC. AH dissolution kJ/mol

The standard enthalpy change for the following reaction is 62.2 kJ at 298 K. 2 Ag₂0(s) 4 Ag(s) + O₂(g) AH° = 62.2 kJ What is the standard enthalpy change for this reaction at 298 K? 2 Ag(s) + 1/2O₂(g) →→→ Ag₂O(s) kJ ▬▬▬

Using the standard heats of formation that follow, calculate the standard enthalpy change for the following reaction. 2CO₂(g) +5H₂(g) C₂H₂(g) + 4H₂O(g) AH°rxn= Species AH, (kJ/mol) CO₂(g) -393.5 C₂H₂(g) 226.7 H₂O(g) -241.8 kJ

A bomb calorimeter, or constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods. Since the "bomb" itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter. In the laboratory a student burns a 0.524-g sample of 2-naphthylacetic acid (C₁pH1002) in a bomb calorimeter containing 1070. g of water. The temperature increases from 24.50 °C to 27.60 °C. The heat capacity of water is 4.184 Jg-¹°C-¹. The molar heat of combustion is -5779 kJ per mole of 2-naphthylacetic acid. C12H10O2(s) + 27/2 O₂(g) →→→→12 CO₂(g) +5 H₂O(1) + Energy Calculate the heat capacity of the calorimeter. Ignition wires heat sample Insulated outside chamber Water Sample dish Stirrer Thermometer Burning sample Steel bomb Combustion (bomb) calorimeter.

The standard beat of formation for CdO(s) is-258 kJ/mol at 298 K. Write the formation equation for CdO(s) that goes with this value of AH Be sure to specify states. Write fractions with a slash, such as 1/2 for one half. If a box is not needed leave it blank.

An automobile engine provides 576 Joules of work to push the pistons. In this process the internal energy changes by -2736 Joules. What is q for the engine? This represents the amount of heat that must be carried away by the cooling system. q= Joules

The following information is given for mercury at 1 atm: boiling point = 357 °C melting point = -39 °C specific heat solid = 0.141 J/g°C specific heat liquid = 0.139 J/g°C AHvap (357 °C) = 59.3 kJ/mol AHfus(-39 °C) = 2.33 kJ/mol What is AH in kJ for the process of freezing a 38.0 g sample of liquid mercury at its normal melting point of -39 °C. kl

A 12.17 g sample of an unknown hydrocarbon undergoes combustion in a bomb calorimeter with a calorimeter constart of 18.5 kJ/°C. If the calorimeter increases in temperature from 19.77 to 29.04 °C, what is the value of q (in kJ) for the combustion reaction. Include the correct sign with your value. (Be careful. I gave you more information than you need.)

The following reaction is endothermic. SiBr4(1)→→→→Si(s) + 2 Br₂(1) AH(1) = 457 kJ Calculate the enthalpy change for the reaction of the elements to form one mole of SiBr4(1).

An automobile engine generates 2140 Joules of heat that must be carried away by the cooling system. The internal energy changes by -2690 Joules in this process. What is w for the engine? This represents the amount of work available to push the pistons in this process. W= Joules

Energy change is the sum of heat and work: AE = q +w. Work is calculated by: w=-PAV What is the change in energy (in joules) if a reaction absorbs 30.6 J of heat and increases in volume from 0.250L to 0.750L at a constant pressure of 1.021 atm? Please include the correct sign with your numerical result. (Note: Make sure your units are consistent when combining energy terms. The conversion factor you need is: 1 L-atm = 101.3 J)

The reaction described takes place in solution in a coffe-cup style calorimeter. We will assume that the cups absorb or release a negligible amount of heat so we will not need to worry about the calorimeter constant or acal If the total mass of the solution in the calorimeter is 21.65 g and and the solution increases from 19.89 °C to 51.17 °C, what is the value of q in joules for the reaction. Include the correct sign with your value of q. C= 4.179 J/g°C for the solution.

A 30.0 g sample of water at 280 K is mixed with 50.0 g of water at 330 K. Calculate the final temperature of the mixture (in K) assuming no heat is lost to the surroundings. (Enter answer without units and report to 3 sig figs)

A 100.0 mL sample of 0.300 M NaOH is mixed with a 100.0 mL sample of 0.300 M HNO3 in a coffee cup calorimeter. If both solutions were initially at 35.0 °C and the temperature of the resulting solution was recorded as 37.0 °C, determine the AHrxn (in kJ/mol of H₂O). Assume that no heat is lost to the calorimeter or the surrounding

A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the heat capacity of the calorimeter (Ccal) for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 72.0 °C into the calorimeter containing a 50.0 mL sample of water at 25.0 °C. She carefully records the final temperature of the water as 44.0°C. What is the value of Ccal for the calorimeter?

Save A 54.84 g of water at 81.9 °C is added to a calorimeter that contains 49.55 g of water at 41.6 °C. If the final temperature of the system is 59.4 °C, what is the calorimeter constant (C calorimeter)? Use 4.184 yg °C for the heat capacity of water.

part 1 of 2 Calculate the standard entropy change for the dimerization of NO2: 2 NO2(g) → N₂O4(g) at 298 K, if So AH (K-mal) (hd) 240.06 33.18 NO₂(g) N₂O4(g) 304.29 9.16 part 2 of 2 Using the given data, what is the standard free-energy change?

Hot coffee is poured into a cold stream. Which of the following statements is correct? a. The stream absorbs heat; the coffee loses heat. b. Both the stream and the coffee lose heat; neither gains it. c. The stream loses heat; the coffee absorbs heat. d. Both the stream and the coffee gain heat; neither loses it.

A gas is compressed and during this process the surroundings do 162 J of work on the gas. At the same time, the gas absorbs 204 J of heat from the surroundings. What is the change in the internal energy of the gas?

8. In a thermodynamic study, a scientist focuses on the properties of a solution in an apparatus as illustrated above. A solution is continuously flowing into the apparatus at the top and out at the bottom, such that the amount of solution in the apparatus is constant with time. The solution in the apparatus is a. closed b. open c. isolated d. none of the above