Question

The equation shows one mole of ethanol fuel being burned in oxygen. Convert the energy
released into its equivalent mass.
C2H5OH(l) + 3 O2(g) -> 2 CO2(g) + 3 H2O (l) H = -1418 kJ/mol

Answer 1

@matt101

Answer 2

@Somy please i need help

Answer 3

Any idea?

Answer 4

trying to remember T_T

Answer 5

there is no T or C given so im trying to figure how to get to mass without them

Answer 6

We want to go from kJ/mol to kJ/g.

In this case, the -1418 kJ/mol is referring to moles of C2H5OH. All you need to do is find the mass of 1 mol of C2H5OH (call that x), and then simplify the expression: -1418 kJ/x g.

Answer 7

oh god i misunderstood the q +_+

Answer 8

Hmm im still confused

Answer 9

I dont understand anything about conservation of mass lol...

Answer 10

its formula manipulation

Answer 11

using units

Answer 12

You don't need to worry about conservation of mass for this question.

We're just switching the units of the enthalpy. Instead of saying energy per mole of C2H5OH, we want to find energy per mass (gram) of C2H5OH.

The reaction gives us the enthalpy for 1 MOLE of C2H5OH, so we just need to find the MASS of this quantity. What's the mass (in grams) of 1 mole of C2H5OH?

Answer 13

6.0684 g/mol

Answer 14

What's the molar mass of C2H5OH?

Answer 15

46.06844 g/mol

Answer 16

\[\sf\frac{ KJ }{ mole }\]
\[\sf mole = \frac{ mass }{ Mr }\]
\[\sf mass = mole \times Mr\]

\[\sf \frac{ KJ }{ mole } = \frac{ KJ }{ mole \times Mr }\]

so to change \[\sf \frac{ KJ }{ mole }\] to \[\sf \frac{ KJ }{ g }\]
you need to multiply value of \[\sf \frac{ KJ }{ mole }\] to \[\sf \frac{ 1 }{ Mr ~ of ~your~ compound }\]

Answer 17

How do I do that?

Answer 18

Right - that's the molar mass of C2H5OH. So what's -1418 kJ/46 g?