Chemistry Answers

Thermochemical equation for Formation of carbon dioxide gas from carbon (graphite) and oxygen yields 393.5 

kJ of heat.

One mole ammonium nitrate (NH₄NO₃) dissolves in water to produce aqueous 

ammonium ions and nitrate ions accompanied by the absorption of 28.1 kJ of heat

Thermochemical equation for Reaction between solid phosphorous, P₄ and oxygen gas, produces P₃O₆and 

1640.1kJ of heat.

Certain race cars use methanol (CH3OH) as fuel. The combustion of methanol occurs according to the following equation: (Look at the equation below) In a particular reaction, 9.8 moles of CH3OH are reacted with an excess of O2. Calculate the number of moles of H2O formed.

Calorimetry involves the measurement of the ___________________. 

a. quantity of work exchanged between a systems.

b. quantity of heat exchanged between the systems.

c. quantity of heat exchanged between a system and the surroundings.

d. quantity of work exchanged between a system and the surroundings.

The symbol, q-, means ___________. 

a. Work is done on the surroundings.

b. Heat flows from the surroundings to the system.

c. Heat flows from the system to the surroundings.

d. Work is done on both the system and the surroundings.

The amount of energy needed to increase the temperature of a material by 1°C. 

a. specific heat transfer

b. heat capacity

c. coffee cup calorimeter

d. heat constant

The standard enthalpy of a reaction can be ___________. 

a. calculated as the sum between the difference of the standard molar enthalpies of formation of products only.

b. calculated as the difference between the sum of the standard molar enthalpies of formation of reactants only.

c. obtained as the difference between the sum of the standard molar enthalpies of formation of products and reactants.

d. obtained from the different thermochemical equations by applying the first law of thermodynamics.

The amount of heat absorbed or released by a chemical reaction at constant atmospheric pressure. 

a. standard molar enthalpy

b. enthalpy of products

c. enthalpy of reaction

d. enthalpy

When heat flows from the system to its surroundings, heat is ________. 

a. equal

b. positive

c. negative

d. neutral

Convert 27 degrees C to F

Enthalpy of reaction is positive when _______________. 

a. chemical reaction is both endothermic and exothermic.

b. chemical reaction is endothermic.

c. the amount of heat transferred and absorbed are unequal.

d. chemical combustion does not happen.

When work is accomplished on the system, it _________ 

a. gains work and energy is denoted as positive.

b. gains energy and work is denoted as negative.

c. gains work and energy is denoted as zero.

d. gains energy and work is denoted as positive.

Explosion of a firecracker triggered by a spark is _________. 

a. exothermic

b. partly exothermic

c. both endothermic and exothermic

d. endothermic

Hess’s law applies the rule that enthalpy is an ________. 

a. extensive property.

b. intensive property.

c. extensive process.

d. intensive process

Law of Conservation of Energy states that, ______________.

a. The energy of the system and the of the surroindings are unrelated.

b. Energy can neither be created nor destroyed.

c. Energy can neither be created nor transferred.

d. The change in energy of a system is equal to the heat absorbed and released.

A calorimeter is an____________________. 

a. insulated coffee cup that that transfers an immense amount of heat.

b. excellent insulator that works without a thermometer.

c. insulated apparatus that contains water or any liquid of known heat capacity.

d. apparatus that has water or any liquid with unknown heat capacity.

Thermal decomposition of limestone to form calcium oxide and carbon dioxide is ________. 

a. exothermic

b. endothermic

c. both endothermic and exothermic

d. partly exothermic

The first law of thermodynamics hints that __________. 

a. net energy flow to or from any surroundings comes in either heat or work.

b. net heat flow to or from any system comes in either energy or work.

c. net energy flow to or from any system comes from the surroundings.

d. net energy flow to or from any system comes in either heat or work.

Hess’s law states that the __________________. 

a. enthalpy of a sum of a series of reactions is unequal to the sum of the enthalpies of those two reactions.

b. enthalpy of a sum of a series of reactions is equal to the sum of the enthalpies of those two reactions.

c. enthalpy of a sum of a series of reactions is equal to the sum of the heat capacities of those two reactions.

d. enthalpy of a sum of two reactions is equal to the difference of the enthalpies of those two reactions.

Heat is a form energy transfer between objects as an effect of their difference in _________.

a. temperature

b. volume

c. energy

d. pressure