# Question #0d3d9

##### 1 Answer

#### Answer:

#### Explanation:

Start by making sure that you have clear understanding of what **heat capacity** means.

As you can se from the units used to express it, *heat capacity* tells you what the ratio between the amount of **heat added**, in your case, to the bomb calorimeter, and the subsequent **increase in temperature**.

SImply put, a heat capacity of

Mathematically, this is expressed as

#color(blue)(q = C * DeltaT)" "# , where

*final temperature* minus the *initial temperature*

Plug in your values and find **absorbed** by the calorimeter

#q = 2.47"kJ"/color(red)(cancel(color(black)("K"))) * 2.22color(red)(cancel(color(black)("K"))) = "5.4834 kJ"#

Now, the idea here is that the heat **released** by the combustion reaction will be **equal** to the heat **absorbed** by the calorimeter.

#-q_"released" = q_"absorbed"#

The *minus sign* is used here because heat given off carries a negative sign.

So, you know that the combustion of *give off*

Use ethylene's molar mass to determine how many moles you would get in the sample

#0.109color(red)(cancel(color(black)("g"))) * ("1 mole C"_2"H"_4)/(28.053color(red)(cancel(color(black)("g")))) = "0.003886 moles C"_2"H"_4#

So, if **one mole** would produce

#1color(red)(cancel(color(black)("mole"))) * "5.4834 kJ"/(0.003886color(red)(cancel(color(black)("moles")))) = "1141.1 kJ/mol"#

This means that the enthalpy change of combustion for ethylene will be

#DeltaH_"comb" = -color(green)("1140 kJ/mol") -># rounded to three sig figs

The *minus sign* here symbolizes that this much heat is being **released** when one mole of ethylene undergoes combustion.