Ethanol is increasingly being used as a fuel for cars.
The standard enthalpy change of formation of carbon dioxide is -393 kJmol.
The standard enthalpy change of formation of water is --286 kJmol.
The standard enthalpy change of formation of ethanol is -277 kJmol.
What is the standard enthalpy change of combustion of ethanol?

=-522.5\,\, kJmol^{-1}

Explanation:

Firstly, we know that 0.36 g of ethanol burned, so we can convert this into a number of moles.

Using a formula triangle to calculate the number of moles of ethanol in a 0.36 gram sample

Secondly, we can use \Delta H=cm\Delta T to calculate the enthalpy change in the experiment described in the question (ie when 0.008 moles of ethanol is burned).

\Delta H=cm\Delta T = 4.18 x 0.2 x 5

= 4.18 kJ

Lastly, we can use the enthalpy change for the experiment in the question to calculate the enthalpy of combustion (ie when one mole of ethanol is burned).

0.008\,\,moles\,\,ethanol =4.18kJ

1\,\,mole\,\,ethanol = \frac{1}{0.008} \times 4.18

=-522.5\,\, kJmol^{-1}

answer: option (4) is the correct answer.

explanation:

areas which are at low altitudes and near the equator tend to receive direct sunlight from the sun. hence, heat energy or radiations from the sun make these areas warmer and they have warmest water.

whereas areas which are at high altitudes and away from the equator do no receive direct sunlight. hence, no direct contact from the sun makes these regions colder and thus, they have colder water.

thus, we can conclude that the statement areas at low latitudes near the equator have the warmest water because they receive the most direct sunlight best explains the relationship between an area's geography and the temperature of its surface water.

14 days is the half-life of phosphorus-32