Exam 10: Thermochemistry

A 6.55 g sample of aniline (C₆H₅NH₂,molar mass = 93.13 g/mol)was combusted in a bomb calorimeter.If the temperature rose by 32.9°C,use the information below to determine the heat capacity of the calorimeter. 4 C₆H₅NH₂(l)+ 35 O₂(g)→ 24 CO₂(g)+ 14 H₂O(g)+ 4 NO₂(g) ΔH°_rxn = -1.28 × 10⁴ kJ

Calculate the amount of heat (in kJ)required to raise the temperature of a 79.0 g sample of ethanol from 298.0 K to 385.0 K.The specific heat capacity of ethanol is 2.42 J/g°C.

How much heat is absorbed when 45.00 g of C(s)reacts in the presence of excess SO₂(g)to produce CS₂(l)and CO(g)according to the following chemical equation? 5 C(s)+ 2 SO₂(g)→ CS₂(l)+ 4 CO(g)ΔH° = 239.9 kJ

When 50.0 mL of 0.400 M Ca(NO₃)₂ is added to 50.0 mL of 0.800 M NaF,CaF₂ precipitates,as shown in the net ionic equation below.The initial temperature of both solutions is 22.00°C.Assuming that the reaction goes to completion,and that the resulting solution has a mass of 100.00 g and a specific heat of 4.18 J/(g ∙ °C),calculate the final temperature of the solution. Ca²⁺(aq)+ 2 F^-(aq)→ CaF₂(s)ΔH° = -11.5 kJ

A 4.98 g sample of aniline (C₆H₅NH₂,molar mass = 93.13 g/mol)was combusted in a bomb calorimeter with a heat capacity of 4.25 kJ/°C.If the temperature rose from 29.5°C to 69.8°C,determine the value of ΔH°_comb for aniline.

The specific heat capacity of solid copper metal is 0.385 J/gK.How many joules of heat are needed to raise the temperature of a 1.55-kg block of copper from 33.0°C to 77.5°C?

Determine the final temperature of a gold nugget (mass = 376 g)that starts at 398 K and loses 4.85 kJ of heat to a snowbank when it is lost.The specific heat capacity of gold is 0.128 J/g°C.

Identify an element that is NOT in its standard state.

Use the bond energies provided to estimate ΔH°_rxn for the reaction below. PCl₃(g)+ Cl₂(g)→ PCl₅(l)ΔH°_rxn = ? Bond Bond Energy (kJ/mol) Cl-Cl 243 P-Cl 331

Two solutions,initially at 24.60°C,are mixed in a coffee cup calorimeter (C_cal = 15.5 J/°C).When a 100.0 mL volume of 0.100 M AgNO₃ solution is mixed with a 100.0 mL sample of 0.200 M NaCl solution,the temperature in the calorimeter rises to 25.30°C.Determine the DH°_rxn for the reaction as written below.Assume that the density and heat capacity of the solutions is the same as that of water. NaCl(aq)+ AgNO₃(aq)→ AgCl(s)+ NaNO₃(aq)DH°_rxn = ?

Use the bond energies provided to estimate ΔH°_rxn for the reaction below. C₂H₄(g)+ H₂(g)→ C₂H₆(g)ΔH°_rxn = ? Bond Bond Energy (kJ/mol) C-C 347 C-H 414 C=C 611 C≡C 837 H-H 436

The temperature rises from 25.00°C to 29.00°C in a bomb calorimeter when 3.50 g of sucrose undergoes combustion in a bomb calorimeter.Calculate ΔE_rxn for the combustion of sucrose in kJ/mol sucrose.The heat capacity of the calorimeter is 4.90 kJ/°C.The molar mass of sugar is 342.3 g/mol.

Identify what a bomb calorimeter measures.

According to the following thermochemical equation,what mass of H₂O (in g)must form in order to produce 488 kJ of energy? SiO₂(s)+ 4 HF(g)→ SiF₄(g)+ 2 H₂O(l)ΔH°_rxn = -184 kJ

Using the following equation for the combustion of octane,calculate the amount of grams of carbon dioxide formed from 100.0 g of octane.The molar mass of octane is 114.33 g/mole.The molar mass of carbon dioxide is 44.0095 g/mole. 2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O ΔH°_rxn = -11018 kJ

Which of the following signs on q and w represent a system that is doing work on the surroundings,as well as gaining heat from the surroundings?

Which of the following is NOT a standard state?

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

A 12.8 g sample of ethanol (C₂H₅OH)is burned in a bomb calorimeter with a heat capacity of 5.65 kJ/°C.Using the information below,determine the final temperature of the calorimeter if the initial temperature is 25.0°C.The molar mass of ethanol is 46.07 g/mol. C₂H₅OH(l)+ 3 O₂(g)→ 2 CO₂(g)+ 3 H₂O(g)ΔH°_rxn = -1235 kJ

Which of the following processes is exothermic?