Energetics Questions and Answers

C₂H4(g) + H₂O(g) CH3CH₂OH(g) Using standard thermodynamic data at 298K, calculate the entropy change for the surroundings when 2.28 moles of C₂H4(g) react at standard conditions.

How much energy is required to raise the temperature of 15.6 grams of ice from -8.76 degrees Celsius to 85.9 degrees Celsius? Do not include units, answer in 3 sig figs.

For an exothermic reaction, the enthalpies of products are always lower than that of reactants. always the same as that of reactants. always higher than that of reactants. independent of enthalpies of reactants.

What is the mass in grams of carbon dioxide that would be required to react with 37.9 g of LIOH in the following chemical reaction? 2 LIOH(s) + CO₂(g) → Li₂CO3(s) + H₂O(I)

The reaction above is the reaction. exothermic, absorbed exothermic, released endothermic, absorbed endothermic, released and therefore heat is by

Thallium(1) chloride can be detected by the addition of silver nitrate. If thallium(1) chloride is present, a white precipitate of silver chloride will be seen. TICI(aq) + AgNO3(aq) → TINO3(aq) + AgCl(s) If 0.800 gram of TICI is present in a solution, what mass of silver chloride would precipitate out? 1.34 g AgCl 143 g AgCl 0.478 g AgCl 0.00333 g AgCl

The following information is given for n-pentane at 1 atm: Tf = 36.20°C Tm-129.70°C Specific heat gas = 1.650 J/g °C Specific heat liquid = 2.280 J/g °C ΔHvap (36.20°C) = 357.6 J/g ΔHfus (-129.70°C) = 116.7 J/g A 46.30 g sample of liquid n-pentane is initially at -5.50°C. If the sample is heated at constant pressure (P = 1 atm), kJ of energy are needed to raise the temperature of the sample to 64.70°C.

The following thermochemical equation is for the reaction of ammonium nitrate(s) to form dinitrogen monoxide(g) and water (g). NH4NO3(s) N₂O(g) + 2H₂O(g) ΔH = -35.9 kJ/mol-rxn How many grams of NH4NO3(s) would have to react to produce 13.3 kJ of energy?

(NH4)₂S is a strong electrolyte. Determine the concentration of each of the individual ions in a 0.400 M (NH4)2S solution. [NH4+] = [S2-] =

As an alternative to combustion of coal gas described earlier in this section, coal gas can undergo a process called methanation. 3 H₂(g) + CO(g) → CH4(g) + H₂O(g) Determine the enthalpy change involved in the reaction of 300 g of carbon monoxide in this methanation reaction, using the following reference equations and enthalpy changes. (1) 2 H₂(g) + O2(g) → 2H₂O(g) → 2 CO(g) (2) 2 C) + O2(g) (3) CH4 +202(g) (4) C+ O2(g) CO₂(g) + 2 H₂O(g)

What amount of heat (in kJ) is required to convert 21.3 g of an unknown liquid (MM = 83.21 g/mol) at 19.2 °C to a gas at 93.5 °C? (specific heat capacity of liquid = 1.58 J/g °C; specific heat capacity of gas = 0.932 J/g °C; ΔHvap = 22.5 kJ/mol; normal boiling point, Tb = 57.3°C)

How much heat in kcal must be added to 0.62 kg of water at room temperature (20°C) to raise its temperature to 50°C?

A glazed doughnut contains 22 g of carbohydrate, 12 g of fat, and 2 g of protein. How many kjoules of energy does the cheeseburger contain? (The accepted caloric values for foods are 17 kJ/g for carbohydrate, 38 kJ/g for fat, and 17 kJ/g for protein.) Round the answer to the tens place.

Iron has a specific heat of 0.444 J/g. How many kJ of heat are needed to raise the temperature of 56.2 g of iron by 100°C? 2495 kJ O 5.62 x 10-² kJ 2.50 kJ 1.27 x 104 kJ

If the initial sample is 2.75 g, what mass of the original iridium-192 remains after 65 days? mass remaining: Estimate the half-life of the radioisotope. half-life:

What quantity of heat, in kJ, is required to convert 50.0 g of ethanol (C₂H5OH) at 23.0°C to a vapor at 78.3°C (its boiling point)? (specific heat capacity of ethanol = 2.46 J/g. C; ΔHvap = 39.3 kJ/mol)

What amount of heat (in kJ) is required to convert 10.1 g of an unknown solid (MM = 67.44 g/mol) at -15.4 °C to a liquid at 42.7 °C? (specific heat capacity of solid = 1.95 J/g °C; specific heat capacity of liquid = 1.18 J/g °C; AHfus = 5.72 kJ/mol; normal freezing point, Tf = 28.3°C)

Calculate the amount of heat needed to melt 83.5 g of solid ethanol (CH3CH2OH) and bring it to a temperature of 14.3 °C. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

Which is not an example of potential energy? All are examples of potential energy An apple in a tree None are examples of potential energy An apple falling An apple on the ground at the top of a hill

Calculate the amount of heat needed to melt 142. g of solid ethanol (CH3CH2OH) and bring it to a temperature of 18.3 °C. Round your answer to 3 significant digits. Also, be sure your answer contains a unit symbol.

For a certain chemical reaction, the standard Gibbs free energy of reaction at 5.00 °C is 71.8 kJ. Calculate the equilibrium constant K for this reaction. Round your answer to 2 significant digits.

The heater used in a 4.23 m x 3.59 m x 2.88 m dorm room uses the combustion of natural gas (primarily methane gas) to produce the heat required to increase the temperature of the air in the dorm room. Assuming that all of the energy produced in the reaction goes towards heating only the air in the dorm room, calculate the mass of methane required to increase the temperature of the air by 6.39 °C. Assume that the specific heat of air is 30.0 J/K-mol and that 1.00 mol of air occupies 22.4 L at all temperatures. Enthalpy of formation values can be found in this table. Assume gaseous water is produced in the combustion of methane. mass of methane: 09

The oxidation of copper(I) oxide, Cu, O(s), to copper(II) oxide, CuO(s), is an exothermic process. 2 Cu₂O(s) + O₂(g) →→→ 4 CuO(s) kJ mol Calculate the energy released as heat when 34.43 g Cu₂O(s) undergo oxidation at constant pressure. energy released: -70.3 Incorrect AH = -292.0 kJ

Calculate AHxn for the reaction, 4HF(g) + O₂(g) → 2F2(g) + 2H₂O(1), from the following data. F2(g) + H₂(g) → 2HF(g) 2H₂(g) + O₂(g) → 2H₂O(1) -607 kJ +251 kJ +502 kJ -1110 kJ +35 kJ AHxn=-537 kJ AHxn=-572 kJ

Consider these reactions, where M represents a generic metal. 2 M(s) + 6HCl(aq) → 2 MC1₂ (aq) + 3 H₂(g) - HCI(g) → HCl(aq) H₂(g) + Cl₂(g) → 2 HCl(g) MCI, (s)- MCI, (aq) Use the given information to determine the enthalpy of the reaction 2 M(s) + 3 Cl₂(g) 2 MCI, (s) 1. 2. 3. 4. - AH₁ = -815.0 kJ AH₂ = -74.8 kJ AH3 = -1845.0 kJ AH₂ = -107.0 kJ

Calculate the standard enthalpy change for the reaction at 25 °C. Standard enthalpy of formation values can be found in this list of thermodynamic properties. C₂H₂(g) +50₂(g) →→→ 3 CO₂(g) + 4H₂O(g)

A solution is made by mixing 255.0 mL of ethanol initially at 10.7 °C with 255.0 ml. of water initially at 24.3 'C. What is the final temperature of the solution assuming that no heat is lost? The density of ethanol is 0.789 g/mL. and the density of water is 1.00 g/mL. The specific heat of ethanol is 2.46 J/g °C and the specific heat of water is 4.184 J/g °C.

Which statement is true of the internal energy of the system and its surroundings following a process in which ΔEsys = +94 kJ? The system and surroundings both gain 94 kJ of energy. The system gains 94 kJ of energy and the surroundings lose 94 kJ of energy. The system loses 94 kJ of energy and the surroundings gain 94 kJ of energy. The system and surroundings both lose 94 kJ of energy.

Which statement best defines specific heat? The amount of heat required to increase the temperature of 1 L of a substance by 1 °C. The amount of heat required to increase the temperature of 1 g of a substance by 1 °C. The amount of heat required to increase the temperature of a specific object, such as a calorimeter, by 1 °C. The amount of heat required to increase the temperature of 1 mol of a substance by 1 °C.

Phosphoryl chloride, Cl3 PO, is made by the reaction shown below: P4010 + 6PC15 --> 10Cl3 PO How much energy could be obtained when 50g of tetraphorphous deacaoxide, P4010, is reacted? You are given the following thermochemical equations: (1) P4 +6Cl2 --> 4 PCl3 (2) P4 +502 --> P4010 (3) PCl3 + Cl2 --> PC15 A H° = -1272 KJ A H° = -2915 KJ A H° -125 KJ (4) PCl3 + 02 --> Cl3 PO A H° = -267 KJ

The average person uses 2,500.0 Cal of energy per day. How many Joules is that? Remember that a food calorie (Cal) is 1,000 chemistry calories (cal).

Calculate the value of AH° for the following reaction: P4O10(s) + 6PCl5(g) ---> 10Cl3PO(g) using the following four equations:

The combustion reaction of 1-pentanol is: C5H11OH(l) + 15/2O2(g) → 5 CO2(g) + 6 H2O(l) ΔH, (CO₂(g)) = -393.5 kJ/mol ΔHO, (H₂O()) = -285.8 kJ/mol heat of formation of 1-pentanol.

Calculate the energy required to heat 754.0 g of iron from 3.3 °C to 18.1 °C. Assume the specific heat capacity of iron under these conditions is -1 1 0.449 J-g¹K¹. Round your answer to 3 significant digits.

11.08 g of liquid methanol (CH₂OH) is burned in excess oxygen gas according to the following Type reaction: 2 CH3OH(l) + 3 O₂(g) → 2 CO₂(g) + 4H₂O(l) The reaction releases 251 kJ of heat. What is the AH for the reaction as written?

HCI(g) can be synthesized from H₂(g) and Cl₂(g) as represented above. A student studying the kinetics of the reaction proposes the following mechanism Step 1: Cl₂(g) →→2 Cl(g) AH = 242 kJ/molrxn Step 2: H₂(g) + Cl(g) → HCI(g) + H(g) Step 3: H(g) + Cl(g) → HCI(g) AH = 4 kJ/molrxn AH = -432 kJ/molrxn A B What is the value of the enthalpy change per mole of HCI(g) produced? -93 kJ -121 kJ -186 kJ (slow) (fast) -242 kJ H2(g) + Cl2(g) = 2 HCl(g) Kp = 2 × 1030 at 298 K (fast)

Calorimetry calculations often assume no heat exchange between the calorimeter and the surroundings, but in real life this heat transfer does in fact occur. Correctly complete the following statements regarding the results of actual calorimetry experiments. Zinc reacts with hydrochloric acid in a coffee cup calorimeter and the temperature of the solution increases by 32.3°C. In this experiment, heat flows and the experimentally determined enthalpy change will be -- enthalpy change for the reaction. Citric acid reacts with sodium bicarbonate in a coffee cup calorimeter and the temperature of the solution decreases by 18.7°C. In this experiment, heat flows -- the calorimeter, the measured temperature change is temperature change that would occur in a perfectly insulated calorimeter, and the experimentally determined enthalpy change will be --

A chemical reaction occurs inside a cylinder with a movable piston at constant pressure of 0.972 atm. The chemical reaction releases 431.6 J of heat to the surroundings. Before the reaction occurs the volume of the cylinder is 3.38 L. During the reaction the cylinder is forced down to a final volume of 0.94 L. Calculate the change in internal energy for this process (in joules).

Use constant-pressure calorimetry to determine enthalpy change. The salt barium bromide is soluble in water. When 11.8 g of BaBr₂ is dissolved in 113.00 g of water, the temperature of the solution increases from 25.00 to 27.06 °C. Based on this observation, calculate the enthalpy of dissolution of BaBr2 (in kJ/mol). Assume that the specific heat of the solution is 4.184 J/g °C and that the heat absorbed by the calorimeter is negligible.

When 0.483 g of trimethylamine, C,H,N, is burned in a bomb calorimeter, the temperature of Type numbers in the boxes. the calorimeter increases by 4.39°C. The bomb has a heat capacity of 864 J/°C and is submerged in 835 mL of water. Assume the density of water is 1.00 g/mL. How much heat, in joules, was produced by the combustion of the trimethylamine sample? What is the experimental heat of combustion of trimethylamine (in kilojoules per mole of trimethylamine)?

Calculate the reaction entropy (ΔSrxn) for the following reaction: Si + 2 Cl₂ → SICI4 A -133.84 J/mol K B 126.56 J/mol K C 253.12 J/mol K D 794.7 J/mol K

The heat of formation of liquid methoxyethane (CH3OC2H5) is -216.4 kJ/mol. Which of the following is the correct heat of formation reaction for liquid methoxyethane?

During the process of photosynthesis, chlorophyll converts energy. When a bowl of hot soup (the system) is placed in a cold room, energy flows from the and the internal energy of the system to the energy into When iron reacts with acetic acid, the temperature of the reaction mixture increases. This process is

qis negative when heat is transferred from the system to the surroundings and wis positive when work is done on the system by the surroundings. When sweat evaporates from the skin, cooling the skin (the evaporating sweat is the system). the sign of q (heat) for the system is negative and the energy exchange is primarily due to When a bicycle tire is inflated (the tire is the system), the sign of w (work) for the system is and the energy Exchange is primarily due to --

Hess's law states that "the heat released or absorbed in a chemical process is the same whether the process takes place in one or in several steps." It is important to recall the following rules: 1. When two reactions are added, their enthalpy values are added. 2. When a reaction is reversed, the sign of its enthalpy value changes. 3. When the coefficients of a reaction are multiplied by a factor, the enthalpy value is multiplied by that same factor. V Part A Calculate the enthalpy of the reaction given the following reactions and enthalpies of formation: 1. N₂(g) + O2(g)-NO2(g), AH = 33.2 kJ 2. N2(g) + O2(g) →NO(g), AH = 90.2 kJ Express your answer with the appropriate units. 2NO(g) + O₂(g) →2NO₂(g) View Available Hint(e)

Tsunami waves generally carry a mass (m) of 770 kg of water, travel at a velocity (v) of approximately 10 m/s and have a height (h) of 10 m at landfall. The colony structures can withstand a total energy (TE) 135,000 J before catastrophic damage occurs. a. Calculate the kinetic energy (KE) of a tsunami wave based on the provided data. KE= 38,500 J 077,000 J O 7700 J O 3,850 J

14A potent donor. Consider the following reaction: ATP + pyruvate phosphoenolpyruvate + ADP (a) Calculate AG" and K' using the data given in Table 15.1. at 25°C for this reaction by eq (b) What is the equilibrium ratio of pyruvate to phospho- enolpyruvate if the ratio of ATP to ADP is 10?

Calculate the quantity of energy required to vaporize 200. mL of C6H6 at 25 °C. The density of C6H6 is 0.870 g/mL, and the vaporization enthalpy is 33.9 kJ/mol.

How many grams of water can be heated from 24.6°C to 37.7°C by the heat released from 88.1 g of iron that cools from 89.2°C to 27.9°C?

The work done on the system when five moles of an ideal gas at 300 K is compressed isothermally and reversibly to 1/10th of its original volume (R = 2 cal) is a kcal. The value of a (rounded off to the nearest integer) is_