Cloudy skies and precipitation. Rain is normally caused by water vapor within the condensation of the low pressure system.
Answer: C. ethanol
The enthalpy of combustion is the amount of heat produced when one mole of ethanol undergoes complete combustion at 25 ° C and 1 atmosphere pressure, yielding products also at 25 ° C and 1 atm.
<u>The enthalpy of combustion of the unknown compound is</u>
ΔH = - 320 kJ / 0.25 mol = - 1280 kJ / mol
<u>To choose a probable compound according to this combustion enthalpy, we must evaluate the deviation in relation to the values reported in the literature for the three probable compounds</u> (methane, ethylene and ethanol). The deviation (e%) will be calculated according to the following equation,
e% = ( | ΔHx - ΔH | / ΔHx ) x 100%
where ΔHx is the enthalpy of combustion of the probable compound.
The following table shows the combustion enthalpies of the probable compounds and their deviation in relation to the enthalpy of ΔH = - 1280 kJ / mol
Compound Enthalpy of combustion (kJ/mol) Deviation
Methane - 890.7 43.8%
Ehylene -1411.2 9.3%
Ethanol -1368.6 6.5%
According to the previous table, we can say that the most probable compound is ethanol, since it has the smallest deviation in relation to the experimental enthalpy value of combustion.
The unit for work is ENERGY
Answer:
B. It represents the change in enthalpy for the reaction.
Explanation:
The potential energy diagram for a chemical reaction shows its potential energy plotted against the reaction progress coordinate. The potential energy diagram shows how the potential energy of reactants and products vary as reactants are converted into products.
The potential energy of the system refers to energy stored in the chemical bonds of reactants and products. The difference between the potential energy of reactants and products is known as the enthalpy of reaction. This difference in potential energy may be positive or negative. A positive difference in potential energy implies an endothermic reaction while a negative difference in potential energy implies an exothermic reaction.
