The combustion of how many moles of ethane (c2h6) would be required to heat 851 g of water from 25.0°c to 98.0°c? (assume liquid water is formed during the combustion.)

Answer : The number of moles of ethane required will be 0.166 mole.

Explanation :

First we have to calculate the heat absorbed by water.

where,

q = heat absorbed = ?

m = mass of water = 851 g

c = specific heat of water =

= final temperature =

= initial temperature =

Now put all the given values in the above formula, we get:

        (1 kJ = 1000 J)

Now we have to calculate the moles of ethane required.

where,

= enthalpy of combustion of ethane = 1560.7 kJ/mol (standard value)

q = heat absorbed = 259.67 kJ

n = number of moles of ethane = ?

Therefore, the number of moles of ethane required will be 0.166 mole.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

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