Question 1

The high heat capacity of water ensures that cities and towns near large bodies of water will have cooler summers and milder winters compared to other places that are located inland.

Accepted Answer

The high heat capacity of water allows it to absorb and store large amounts of heat, moderating temperature fluctuations and leading to cooler summers and milder winters in nearby areas.

Question 2

The heat generated in a typical chemical reaction can be removed by pumping cold water around the outside of the vessel in which the reaction occurs.

Accepted Answer

Cold water can absorb and carry away heat from the reaction vessel, helping to maintain a stable temperature during the reaction.

Question 3

The hazards associated with highly exothermic chemical reactions can be alleviated by calculating the heat of the reaction from standard heats of formation, knowing how fast the heat is released, and the rate at which it can be removed from the reaction vessel.

Accepted Answer

Calculating the heat of reaction and understanding the heat release and removal rates help in designing safety measures to manage the risks of exothermic reactions.

Question 4

At elevated temperatures, any volatile substances in a chemical reaction can be quickly converted to gases, which tend to decrease the pressure within a reaction vessel.

Accepted Answer

When volatile substances are converted to gases, they increase the number of gas molecules, which typically increases the pressure within a reaction vessel, not decrease it.

Question 5

When the rate at which a chemical reaction generates heat is faster than the rate at which the equipment can remove the heat, the reaction is considered endothermic in nature, and the heat is used to generate more of the products.

Accepted Answer

An endothermic reaction absorbs heat from its surroundings, whereas the scenario described is characteristic of an exothermic reaction, which releases heat.

Question 6

A large oceangoing container vessel (200,000 tons)was drifting at just 1.5 miles per hour on the tide when it struck the bridge pylon. Last year a 4500 pound speedboat struck the same pylon while going 48.5 miles per hour. Which possessed more kinetic energy? Use 1 pound = 0.4536 kg = 5.000 × 10⁻⁴ ton, 1 mile = 1.609 km.Hint: The formula for kinetic energy is KE = mv².

Accepted Answer

The answer of A large oceangoing container vessel (200,000 tons)was...

Question 7

Explain how it is possible for a person to freeze to death when the temperature of their surroundings is above their body temperature.Hint: Focus on the kinetic energy of individual particles.

Accepted Answer

The answer of Explain how it is possible for a...

Question 8

A constant pressure calorimeter has metal parts (heat capacity of 850.0 J °C⁻¹)and 1020 grams of oil (specific heat = 2.248 J g⁻¹ °C⁻¹), both at 24.50°C. Two metal slugs, one a 460.0 g piece of cobalt and the other a 360.0 g piece of cadmium were removed from an oven that was maintained at 240.0 °C and added to the calorimeter. If no heat was lost to the surroundings, what would be the final temperature in the calorimeter? (cadmium, molar heat capacity = 25.34 J mol⁻¹ °C⁻¹; cobalt, molar heat capacity = 25.12 J mol⁻¹ °C⁻¹)Hint: Remember to use moles as an intermediary and pay careful attention to units throughout the problem.

Accepted Answer

The answer of A constant pressure calorimeter has metal parts...

Question 9

A volume of 500.0 mL of 0.220 M HCl(aq)was added to a high quality constant-pressure calorimeter containing 500.0 mL of 0.200 M NaOH(aq). Both solutions have a density of and a specific heat of 4.184 J g⁻¹ °C⁻¹. The calorimeter had a heat capacity of 850.0 J °C⁻¹. The temperature of the entire system rose from 25.60 °C to 26.70 °C. Calculate the heat of reaction, in kJ, per mole of NaOH(aq). Hint: Consider your reaction taking place and pay careful attention to your mole values.

Accepted Answer

The answer of A volume of 500.0 mL of 0.220...

Question 10

Propane is often used to heat homes. The combustion of propane follows the following reaction  If during a winter month a houses furnace runs for one hour a day, and the furnace puts out 1,667 BTU's per minute, how many pounds of propane are needed for that month, assuming a 30 day month? Hint: 1 BTU = 1055 Joules and 1 kg = 2.2 pounds.Hint: Use the coefficients in the equation and be sure to convert your answer to the correct units.

Accepted Answer

The answer of Propane is often used to heat homes....

Question 11

A volume of 600.0 mL of 0.240 M perchloric acid, HClO₄(aq)was added to a high quality constant-pressure calorimeter containing 400.0 mL of 0.300 M KOH(aq). Both solutions have a density of 1.000 g mL⁻¹ and a specific heat of 4.184 J g⁻¹ °C⁻¹. The calorimeter had a heat capacity of 950.0 J °C⁻¹. The temperature of the entire system rose from 25.30 °C to 26.59 °C. Calculate the heat of reaction, in kJ, per mole of KOH(aq).Hint: Consider your reaction taking place and pay careful attention to your mole values.

Accepted Answer

The answer of A volume of 600.0 mL of 0.240...

Question 12

The formulas of ethylene, water, and ethanol suggests that the reaction,C₂H₄(g)+ H₂O(g)$\rarr$ C₂H₅OH(l)could be made to occur under the correct conditions. This is a wild idea, but Mike says it's just a matter of the right catalyst combination, reactor temperature, and pressure. Using the values in the table below, what is the calculated value of ?H° for Mike's proposed reaction? Hint: Be sure to adjust your signs whenever you reverse a reaction.

Accepted Answer

The answer of The formulas of ethylene, water, and ethanol...

Question 13

Some workers in central research were talking around the lunch table. They claim to have an idea for a process that might possibly convert C₂H₄(g)to C₂H₅OH(l), an alternative fuel. It would require two steps: It is known that for the reaction, NaOH(s)→ NaOH(aq), ΔH° = −44.505 kJ. Using the values below, what is the calculated value of ΔH° for the proposed reaction?Hint: Be sure to adjust your signs whenever you reverse a reaction.

Accepted Answer

The answer of Some workers in central research were talking...

Question 14

A check of the formulas of methane, water, and methanol suggests that the reaction, CH₄(g)+ H₂O(g)$\rarr$ CH₃OH(l)+ H₂(g)could be made to occur under the correct conditions. This is a wild idea, but the chemist thinks it is just a matter of the right catalyst combination, reactor temperature, and pressure. Using the values in the table below, what is the calculated value of ?H° for Mike's proposed reaction Hint: Be sure to adjust your signs whenever you reverse a reaction.

Accepted Answer

The answer of A check of the formulas of methane,...

Question 15

The standard enthalpy of combustion for oxalic acid, H₂C₂O₄(s), is −251.9 kJ mol⁻¹. Using this data and the standard enthalpies of formation, calculate the standard enthalpy of formation of H₂C₂O₄(s), in kJ mol⁻¹.Hint: Pay careful attention to your signs when calculating the enthalpy.

Accepted Answer

The answer of The standard enthalpy of combustion for oxalic...

Question 16

The standard enthalpy of combustion for ethylene glycol, C₂H₆O₂(l), is −1179.5 kJ mol⁻¹. Using this information and the standard enthalpies of formation, ΔH°_f:H₂O(l)= −285.9 kJ mol⁻¹; CO₂(g)= −393.5 kJ mol⁻¹ calculate the standard enthalpy of formation of C₂H₆O₂(l), in kJ mol⁻¹.Hint: Pay careful attention to your signs when calculating the enthalpy.

Accepted Answer

The answer of The standard enthalpy of combustion for ethylene...

Quiz 7: Energy and Chemical Change