Home Homework Help

Browse Homework Solutions

14,588 solutions

Heating and Cooling Curves

Q. Consider the following specific heat capacities: H2O(s) = 2.09 J/g.°C H2O(l) = 4.18 J/g.°C H2O(g) = 2.03 J/g.°C The heat of fusion for water is 334 J/g and its heat of vaporization is 2260 J/g. Calculate the amount of heat required to convert 93 g of ice at -36°C completely to liquid water at 35°C. a) 38 kJ b) 21 kJ c) 7 kJ d) 52 kJ

Solved • Nov 19, 2019

Hess's Law

Q. Calculate the standard enthalpy change for the following chemical equation. 2HCl(g) + F2(g) → 2HF(l) + Cl2(g) Use the following thermochemical equations to solve for the change in enthalpy. 4HCl(g) + O2(g) → 2H2O(l) + 2Cl2(g) ΔH° = -202.4 kJ 1/2H2(g) + 1/2F2(g) → HF(l) ΔH° = -600.0 kJ H2(g) + 1/2O2(g) → H2O(l) ΔH° = -285.8 kJ

Solved • Nov 19, 2019

Hess's Law

Q. Nitric acid can be manufactured in a multi-step process, during which nitric oxide is oxidized to create nitrogen dioxide. 2NO(g) + O2(g) → 2NO2(g) Calculate the standard reaction enthalpy for the above reaction using the following thermodynamic data. N2(g) + O2(g) → 2NO(g) ΔH^+1 = 180.5 kJ N2(g) + 2O2(g) → 2NO2(g) ΔH^+2 = 66.4 kJ a) -114.1 kJ b) -100.3 kJ c) -252.4 kJ d) -246.9 kJ

Solved • Nov 19, 2019

Calorimetry

Q. A piece of metal with a mass of 22 g at 92°C is placed in a calorimeter containing 70.3 g of water at 21°C. The final temperature of the mixture is 25.4°C. What is the specific heat capacity of the metal? Assume that there is no energy lost to the surroundings. a) -0.88 J g^-1°C^-1 b) -1.14 J g^-1°C^-1 c) 1.14 J g^-1°C^-1 d) I have no idea how to even start this. e) 0.88 J g^-1°C^-1

Solved • Nov 19, 2019

Internal Energy

Q. Which of the following will best help determine the direction of heat flow in a system? a) work b) pressure c) temperature d) enthalpy e) internal energy

Solved • Nov 19, 2019

Enthalpy of Formation

Q. What mass liquid of ethanol (CH5OH) must be burned to supply 500 kJ of heat? The standard enthalpy of combustion of ethanol at 298 K is -1368 kJ/mol. a) 16.8 g b) 126 g c) 10.9 g d) 29.7 g

Solved • Nov 19, 2019

Calorimetry

Q. The specific heats and densities of several materials are given below: Calculate the change in temperature produced by the addition of 1 kcal of heat to 100 g of steel. a) 84.7°C b) 37.0°C c) 1.43°C d) 1.18°C

Solved • Nov 19, 2019