Exam 6: Thermochemistry

Calculate the final temperature of a 63.7 g piece of palladium, originally at 100.0 °C, placed inside a coffee cup calorimeter containing 115.0 mL of water at 21.8 °C. The specific heat capacity of water is 4.184 J g^-1 °C^-1, the specific heat capacity of palladium is 0.246 J g^-1 °C^-1, and the density of water is 1.00 g mL^-1.

A 2.38 g sample of phenol (C₆H₆O, molar mass = 94.11 g mol^-1)was combusted in a bomb calorimeter with a heat capacity of 6.65 kJ °C^-1. If the temperature increased from 23.8 °C to 35.4 °C, determine Δ_rU for the combustion of phenol.

Choose the thermochemical equation that illustrates Δ_fH° for Li₂SO₄.

Which of the following processes is exothermic?

Which of the following (with specific heat capacity provided)would show the smallest temperature change upon gaining 200.0 J of heat?

What is the enthalpy change (in kJ)of a chemical reaction that raises the temperature of 250.0 mL of solution having a density of 1.25 g mL^-1 by 10.2 °C? (The specific heat of the solution is 3.733 J g^-1 K^-1.)

A balloon is inflated from 0.0100 L to 0.500 L against an external pressure of 10.00 bar. How much work is done in joules? 100 J = 1 L bar

Use the information provided to determine Δ_rH° for the following reaction: Δ_fH° (kJ mol^-1)CH₄(g)+ 3Cl₂(g)→ CHCl₃(l)+ 3HCl(g)Δ_rH° = ? CH₄(g) -75 CHCl₃(l)-134 HCl(g) -92

Calculate the heat transfer, in kJ, when 1.287 kg of chicken breast (specific heat capacity = 1.82 J g^-1 °C^-1)is removed from a freezer at -17.3 °C and allowed to warm up to 0.00 °C. You need not be concerned about melting of ice or any other phase changes.

Calculate the enthalpy of solution for the dissolution of sodium chloride, NaCl, molar mass = 58.443 g mol^-1. When 6.93 g of NaCl is dissolved in a coffee cup calorimeter containing 100.0 mL of water the temperature dropped from 23.5 °C to 22.4 °C. The specific heat of water is 4.184 J g^-1 °C^-1, and assume the density of the solution is 1.00 g mL^-1.

Calculate the mass of sodium cyanate (NaOCN, molar mass = 65.0066 g mol^-1)required to lower the temperature from 24.1 °C to 23.0 °C in a coffee cup calorimeter containing 98 mL of water. The enthalpy of solution for NaOCN is 19.20 kJ mol^-1. The specific heat of water is 4.184 J g^-1 °C^-1 and assume the density of the solution is 1.00 g mL^-1.

What volume of benzene (C₆H₆, d = 0.88 g mL^-1, molar mass = 78.11 g mol^-1)is required to produce 1.5 × 10³ kJ of heat according to the following reaction? 2C₆H₆(l)+ 15O₂(g)→ 12CO₂(g)+ 6H₂O(g)Δ_rH° = -6278 kJ

Calculate the enthalpy of solution for the dissolution of lithium iodide, LiI, molar mass = 133.85 g mol^-1. When 1.49 g of LiI is dissolved in a coffee cup calorimeter containing 75.0 mL of water the temperature increased from 23.5 °C to 25.7 °C. The specific heat of water is 4.184 J g^-1 °C^-1, and assume the density of the solution is 1.00 g mL^-1.

A student is preparing to perform a series of calorimetry experiments. She first wishes to determine the calorimeter constant (C_cal)for her coffee cup calorimeter. She pours a 50.0 mL sample of water at 345 K into the calorimeter containing a 50.0 mL sample of water at 298 K. She carefully records the final temperature of the water as 317 K. What is the value of C_cal for the calorimeter?

Which of the following processes is endothermic?

A 100.0 mL sample of 0.300 mol L^-1 NaOH is mixed with a 100.0 mL sample of 0.300 mol L^-1 HNO₃ in a coffee cup calorimeter. If both solutions were initially at 35.00 °C and the temperature of the resulting solution was recorded as 37.00 °C, determine the Δ_rH° (in units of kJ mol^-1)for the neutralization reaction between aqueous NaOH and HCl. Assume 1)that no heat is lost to the calorimeter or the surroundings, and 2)that the density and the heat capacity of the resulting solution are the same as water.