Energetics Questions and Answers

51.84 g of water at 81.3 °C is added to a calorimeter that contains 52.02 g of water at 41.9 °C. If the final temperature of the system is 59.4 °C, what is the calorimeter constant (C calorimeter)? Use 4.184 J/g °C for the heat capacity of water.

15. Calculate AH for the reaction of sulfur dioxide with oxygen. 2SO₂(g) + O₂(g) → 2SO,(g) a. -98.9 kJ b. 197.8 kJ c. -197.8 kJ d. Not enough information is given. (AH, SO₂(g) = -296.8 kJ/mol; AH, SO₂(g) = -395.7 kJ/mol)

Calculate the standard entropy change for the production of acetylene from calcium car- bide and water: CaC2(s) + 2H₂O(l) → at 25°C. CaC₂(s) H₂O(l) C₂H2(g) Ca(OH)2(s) Answer in units of C₂H₂(g) + Ca(OH)2(s) So 69.96 Kimol J 69.91 Kmo 200.94 83.39 J K mol J K-mol J K-mol

Calculate the standard reaction entropy for the decomposition of 1 mol calcite (CaCO3(s)) to carbon dioxide gas and solid calcium oxide at 25°C if So 39.75 Kamol J CaO(s) CO₂(g) CaCO3(s) Answer in units of 213.74 l K-mol 92.9 K mol K. mol A

When heating a solution, a scientist detects a temperature increase in the solution during a period of time. Given this information, which of the following statements is the most appropriate characterization of the solution? a. The solution is at boiling point. b. The solution is undergoing a phase change. c. The velocity of molecules in the solution is increasing. d. The solution's temperature increase is proportional to its AH vaporization

Find the standard entropy change for the formation reaction of NH3(g) at 298 K if AH So J K-mal) N₂(g) H₂(g) NH3(g) Answer in units of 191.61 130.68 192.45 kJ) 0 0 -46.11 J K mol part 2 of 2 Using the given data, what is the standard free energy change? Answer in units of kJ/mol.

Which of the following best summarizes Hess's Law? a. Energy released is negative enthalpy and energy used is positive enthalpy b. Energy release is positive enthalpy and energy used is negative enthalpy c. The path taken doesn't matter in reactions; the total change in enthalpy will always be the same d. At a given temperature and pressure, a compound will always have the same enthalpy

14. What is the standard heat of reaction for the following reaction? Zn(s) + Cu²+ (aq) → Zn²* (aq) + Cu(s) a. 216.8 kJ released per mole b. 88.0 kJ absorbed per mole c. 88.0 kJ released per mole d. 216.8 kJ absorbed per mole (AH,* for Cu²+ = +64.4 kJ/mol; AH, for Zn²+ = -152.4 kJ/mol)

Use the following scenario to answer questions 1-4. Into a well insulated cup (meaning no heat lost or gained to the surroundings) a sample of water at room temperature is added. To the water, a sample of metal at 80 °C is added. What object(s) gain(s) energy? Choose all that apply The cup The water The metal. The air surrounding the cup. Cases TO

Which of the following components embedded in the quantity q prove that change in enthalpy is an extensive property? a. Specific heat of substance (C₂) b. Mass of substance (g) c. Temperature change (K) None of the above d.

Part A The specific heat capacity of steel is 450 J/kg C. Find the amount of heat that is needed to raise the temperature of a 11-kg piece of steel from 0°C to 140 °C. Express your answer to two significant figures and include the appropriate units. Q= Submit Part B μA Value Request Answer Units AEO ? How does this compare with the heat needed to raise the temperature of the same mass of water through the same temperature difference? (For water, c = 4190 J/kg- "C) Express your answer using two significant figures. Pea Pearson

For which of the following questions is -41.8 J the answer? Extra info: The specific heat of water is 4.18 J/g°C. Water is the system in this problem. What is the heat transfer to raise the temperature of 1 g water by 1 °C? What is the heat transfer to lower the temperature of 1 g water by 10 °C? What is the heat transfer to lower the temperature of 1 g water by 1 °C? What is the heat transfer to raise the temperature of 1 g water by 10 °C?

4. [3 Point] A 117.67 g sample of silver was heated to 100.0 °C and then quickly dropped into 200.0 g of water (C₁ = 4.184 J/g-"C) in a calorimeter. The temperature of the water changed from 27.5 °C to 29.8 °C. What is the specific heat capacity of silver?

7. You find a 3.10 g pure copper penny in the snow and pick it up. How much energy is absorbed by the penny if its temperature warms from -8.0 °C to a final temperature of 25.0 °C? The specific heat capacity of copper is 0.385 J/g°C.

Be sure to answer all parts. Liquid hydrogen peroxide, an oxidizing agent in many rocket fuel mixtures, releases oxygen gas on decomposition: 2 H₂O₂(0) → 2 H₂O(1) + O₂(g) Calculate the heat for the decomposition of 337 kg of H₂O₂. x 10 KJ AH-196.1 kJ (Enter your answer in scientific notation.)

1. The diagram shows two bowling balls of equal mass. Ball A is resting near the edge of a shelf and Ball B is resting on the ground below. Which of the following statements about the bowling ball is true? * Ball A has more kinetic and potential energy than Ball B Ball A has more potential energy than Ball B, but the same kinetic energy Ball A has less kinetic energy, but more potential energy than Ball B Ball A has less potential and kinetic energy than Ball B

For each of the following irreversible processes, explain how you can tell that the total entropy of the universe has increased: (a) Boiling pasta (b) Scrambling an egg (c) A wave hitting a sand castle (d) Burning gasoline in an engine (e) Exercising

Practice Problem 2: A 5.15 g sample of a salt with a molar mass of 115.23 g/mol is added to a calorimeter containing 54.13 g of deionized water. The initial temperature of the water is 21.53°C, the final temperature of the solution is 18.87°C. What is the molar enthalpy of dissolution in kJ/molt Assume the specific heat of the solution is the same as pure water, 4.184 J/g°C. Remember that the mass of the solution is equal to the mass of the water plus the mass of the salt.

(nedes ponedas (as duas 30- 25- Practice Problem 3: 15- T final 23.37°C AT T initial, acid = 17.78°C initial, base = 17.53°C 15 20 10 time (minutes) 50.00 mL of a 0.687 M HCl is combined with 50.00 mL of 0.752 M NaOH. Using the data from the above graph, calculate the average initial temperature. Then calculate the molar enthalpy of neutralization in kJ/mol. Assume the neutralized solution has a specific heat of 3.90 J/gºC and a density of 1.013 g/mL. Hint: You need to identify the limiting reactant and divide the moles of limiting reactant by its coefficient to determine the moles of reaction. All practice problems must be solved and written in your lab notebook prior to lab. Laboratory Report Cover Sheet Data Sheet ● Answer: -65.7 kJ/mol ● 3 Graphs • Post-lab Sheet I References (1) Silberberg, M. Chemistry: The Molecular Nature of Matter and Change, 9th ed.; McGraw-Hill: New York, NY, 2021. (2) Halpin, J. General Chemistry I, Lecture Notes.

A 80.00 g gold plate is removed from boiling water (1.00x102 °C) and is immediately immersed in a calorimeter containing 61.0 g of water that is initially at 25.13°C. The final temperature is 28.01°C. Calculate the specific heat capacity of gold.

If a solid substance needs 3425) of energy to increase its temperature from 24C to 98C and it has a mass of 243g, what is the specific heat of the substance?

A chemist fills a reaction vessel with 0.535 g calcium phosphate (Ca3(PO4)₂) solld, 0.717 M calcium (Ca²*) aqueous solution, and 0.633 M phosphate (PO³) aqueous aqueous solution at a temperature of 25.0°C. Under these conditions, calculate the reaction free energy AG for the following chemical reaction: Ca3(PO4)₂ (s) 3 Ca²+ (aq) +2PO³(aq) Use the thermodynamic information in the ALEKS Data tab. Round your answer to the nearest kilojoule.

Confirm that magnesium is the limiting reagent in this reaction by showing that all the magnesium is consumed, and some of the HCI is left over. Remember that the limiting reagent is always completely used up and there will always be some of the excess reagent unreacted. For this example let's assume that 0.116 g of magnesium are used. The amount of hydrochloric acid used is the same in all experiments, 4 mL of 6 M hydrochloric acid. Mg(s) + 2 HCI (aq) → MgCl₂ (aq) + H₂(g) In this reaction there are moles of magnesium and moles of hydrochloric acid. Because HCI has a coefficient of 2 in this equation, we understand that 2 moles of HCI are required to react for every 1 mole of magnesium that reacts. We observed that all of the magnesium was used so we know, from the equation, that the moles of HCI used must be 2 X moles of magnesium used. To find the amount of HCI left over, we do the following: "moles of HCI added" - 2 X "moles of magnesium added" = moles of HCI in excess.

Solve the following thermochemical reactions: 2 HCl + PbPbCl2 + H2 H = -1861 J/mole What is the enthalpy if there was 4.5 x 10-³ g of HCI? A) -1.1 x 10-¹ J B 8.375 J C -8.375 J D 3.05 x 10² J

Which of the following is a precipitation reaction? 2 C4H10 (1) + 13 O2 (g) ---> 8 CO2 (g) + 10 H₂O (1) O NaCl(aq) + Lil(aq) → Nal(aq) + LiCl(aq) - O2 Lil(aq) + Hg2(NO3)2(aq) → Hg2l2(s) + 2 LINO3(aq) HCl(aq) + KOH(aq) → KCl(aq) + H₂O(l) O None of these are precipitation reactions.

The heat of vaporization AH, of butane (C4H₁0) is 21.0 kJ/mol, Calculate the change in entropy AS when 957. g of butane condenses at -0.5 °C. Be sure your answer contains a unit symbol. Round your answer to 3 significant digits.

5.73 Using values from Appendix C, calculate the standard enthalpy change for each of the following reactions: (a) 2SO₂(g) + O₂(g) → 2SO, (g) (b) Mg(OH)₂ (s) → MgO (s) + H₂O (1) (c) N₂O, (g) + 4H₂(g) → N₂ (g) + 4H₂O (g) (d) SICI, (1) + 2H₂O (1)→ SiO₂ (s) + 4HCI (g)

5.26 For the following processes, calculate the change in internal energy of the system and determine whether the process is endothermic or exothermic: (a) A balloon is cooled by removing 0.655 kJ of heat. It shrinks on cooling, and the atmosphere does 382 J of work on the balloon. (b) A 100.0-g bar of gold is heated from 25 °C to 50 °C during which it absorbs 322 J of heat. Assume the volume of the gold bar remains constant.

When 1 mole of N₂(g) reacts with H₂(g) to form NH3(g) according to the following equation, 92.2 kJ of energy are evolved. N₂(g) + 3H₂(g) -> 2NH3(g) Is this reaction endothermic or exothermic? What is the value of q?

Use the observations about each chemical reaction in the table below to decide the sign (positive or negative) of the reaction enthalpy AH and reaction entropy ΔS. Note: if you have not been given enough information to decide a sign, select the ''unknown'' option.

Combustion of glucose (C6H₁2O6) is the main source of energy for animal cells: CH₁₂O6 (s) + 60₂ (g) 6CO₂(g) + 6H₂0 (1) ΔGrxn (37 °C)=-2872, kJ One of the most important uses to which this energy is put is the assembly of proteins out of amino acid building blocks. The Gibbs free energy of formation of one peptide bond, joining one amino acid to another, is 21 kJ/mol, Suppose some cells are assembling a certain protein made of 26 amino acids. (Note that the number of peptide bonds in the protein will be one less than the number of amino acids.) Calculate the minimum mass of glucose that must be burned to assemble 650. umol of this protein. Round your answer to 2 significant digits.

A chemist fills a reaction vessel with 9.67 atm chlorine (Cl₂) gas, 9.63 atm phosphorus (P4) gas, and 4.08 atm phosphorus trichloride (PC13) gas at a temperature of 25.0°C. Under these conditions, calculate the reaction free energy AG for the following chemical reaction: 6 Cl₂ (g)+P4 (g) ⇒ 4PCl3 (g) Use the thermodynamic information in the ALEKS Data tab. Round your answer to the nearest kilojoule.

Consider the following reaction: 2CH₂OH(g) → 2 CH₂(g) + O₂(g) AH = +252.8 kJ (a) Is this reaction exothermic or endothermic? (b) Calculate the amount of heat transferred when 24.0 g of CH₂OH(g) is decomposed by this reaction at constant pressure. (c) For a given sample of CH,OH, the enthalpy change during the reaction is 82.1 kJ. How many grams of methane gas are produced? (d) How many kilojoules of heat are released when 38.5 g of CH.(g) reacts completely with O₂(g) to form CH₂OH(g) at constant pressure?

The heat of fusion AH, of acetone e (OC (CH₂)₂) is 5.7 kJ/mol, Calculate the change in entropy ΔS when 21. g of acetone melts at -94.7 °C. Be sure your answer contains a unit symbol. Round your answer to 2 significant digits.

One of the most important sources of energy in living cells is the transformation of glucose, C6H12O6 into lactic acid, C3H603. C6H12O6(s) --> 2C3H6O3(s). Determine the enthalpy change of this reaction if the heat of combustion of glucose is -2827 kJ/mol and the heat of combustion of lactic acid is -1369kJ/mol.

A 34.6g plastic block is heated to 100.0°C in boiling water. It is then transferred to a calorimeter containing 120mL of water at 32.8°C. The final temperature of the system is 49.2°C. Determine the specific heat capacity of the plastic

A chemist fills a reaction vessel with 0.784 g silver chromate (Ag₂ CrO₂) solid, 0.443 M silver (Ag) aqueous solution, and 0.792 M chromate e (Cro, ²-) aqueous solution at a temperature of 25.0°C. Under these conditions, calculate the reaction free energy AG for the following chemical reaction: Ag₂ CrO4(s) 2 Ag* (aq) + CrO² (aq) pak Use the thermodynamic information in the ALEKS Data tab. Round your answer to the nearest kilojoule.

The heat of vaporization AH, of methanol (CH, OH) is 35.3 kJ/mol, Calculate the change in entropy AS when 102. g of methanol condenses at 65.0 °C. Be sure your answer contains a unit symbol. Round your answer to 3 significant digits.

The heat of fusion AH, of ethanol (CH3 CH₂OH) is 4.6 kJ/mol. Calculate the change in entropy AS when 5.6 g of ethanol freezes at -114.3 °C. Be sure your answer contains a unit symbol. Round your answer to 2 significant digits.

Find the AH for the reaction below, given the following reactions and subsequent AH values: CH4(g) + NH3(g) ---> HCN(g) + 3H₂(g) N2(g) + 3H₂(g) ---> 2NH³(g) ΔH = -91.8 kJ C(s) + 2H₂(g)---> CH4(g) ΔH = -74.9 kJ H₂(g) + 2C(s) + N2(g) ---> 2HCN(g) ΔH = +270.3 kJ

A sample of metal absorbs 50 kJ of heat, resulting in a temperature rise of 25.0 °C, determine the mass (in kg) of the copper sample if the specific heat capacity of metal is 0.5 J/g°C. 40 kg 400 kg 4 kg 4000 kg

Consider the reaction below: A(aq) ⇒ B(aq) ΔGrxn= -2.55 kJ A 1.000 M solution of A was heated at 65.7 °C. After some time the concentration of A was determined to be [A] = 0.882 M. What is the maximum amount of work (AG) you can obtain from this reaction when [A] = 0.882 M?

Using the data from the table in Appendix II B in your textbook, or some other reference source, determine the value for the enthalpy change (AH) for reaction (1) and reaction (2) of this lab. (Refer to section 6.9 in your textbook if necessary). Make sure that you use the value for the correct form of the substance [For instance, AH HCI (aq) is different than AH HCI (9)].

Which of the following is true of a spontaneous process? A. O AG is negative and ASuniv is positive B. OAG and ASuniv are both positive C. O AG is positive and ASuniv is negative D. O AG and ASuniy are both negative

A solid sample of sodium carbonate (Na₂CO3(s)) is placed in a test tube containing a solution of ethanoic acid (CH₂COOH(aq)). A gas is produced when the substances are mixed and the temperature of the test tube is observed to decrease. AS for this reaction is Why?

The specific heat of octane, C₂H₁8(1), is 2.22 J/g-K. (a) How many J of heat are needed to raise the temperature of 80.0 g of octane from 10.0 to 25.0 °C? (b) Which will require more heat, increasing the temperature of 1 mol of CH₁8(1) by a certain amount or increasing the temperature of 1 mol of H₂O(l) by the same amount? Show work to support your claim.

If 8.500 moles of water react completely, according to the following equation, what is the total change in enthalpy? 6CO₂ + 6H₂O C6H₁2O6 + 60₂ AHrxn=2,803 kJ • Report your answer using four significant figures.

Calculate DH, in kJ/mol, for C3H8(g) + 502(g) -> 3CO2(g) + 4H₂O(l) given the following standard enthalpies of formation: C3H8(g) = -103.85 kJ/mol CO2(g) = -110.5 kJ/mol H₂O(l) = -285.83 kJ/mol Report your answer to 1 decimal place.

A chemist measures the energy change AH during the following reaction: Cl₂(g) + H₂(g) → 2 HCl(g) Use the information to answer the following question. AH-184. kJ Suppose 31.5 g of Cl₂ react. Calculate how much heat will be released or absorbed. Round your answer to 3 significant digits. ☐kJ C x10 X

If 0.740 g of glucose are burned in a bomb calorimeter, the temperature of the 700. g of water in the calorimeter increases J from 15.30 °C to 18.50 °C. If the heat capacity of the calorimeter is 670.- what is the value of q for the combustion of C' the glucose sample? J • Use Cwater = 4.184 C • Report your answer using three significant figures. Provide your answermelow: kJ