Question

15. Using the information below, calculate ΔHf° for PbO(s)

PbO(s) + CO(g) → Pb(s) + CO2(g) ΔH° = –131.4 kJ
ΔHf° for CO2(g) = –393.5 kJ/mol
ΔHf° for CO(g) = –110.5 kJ/mol

A) –151.6 kJ/mol
B) –283.0 kJ/mol
C) +283.0 kJ/mol
D) –372.6 kJ/mol
E) +252.1 kJ/mol

Answer 1

Is this heat of formation?

Answer 2

use this formula to calculate heat of formation

Answer 3

I think so since thts the topic we've been learning

Answer 4

you know that this is the summation sign right?

Answer 5

I recommend looking at a table some species have a heat of formation = 0, for example O2

Answer 6

or for carbon it is graphite

Answer 7

How do u find the mole? n wht does teh Hf mean?

Answer 8

Hf is the energy needed to be exerted on a system for the atoms to come together I'm pretty sure I actually need to study this for physical chemistry but haven't got around to it

Answer 9

when I say atoms come together I mean the atoms come together to form a specific molecule

Answer 10

It is the entropy of formation

Answer 11

Delta is change so it is the change in energy as a result of the molecule forming

Answer 12

I would just read the wikipedia page on it ha

Answer 13

but yeah if you have any further questions on the mater ask, there are examples on youtube on how to solve such a question.

Answer 14

IM just cconfused about the process on how to do it

Answer 15

do you know what the summation symbol means?

Answer 16

like how 2 use the formula

Answer 17

basically what it means is the sum of a certain amount of values.

So you have the formula

Heat of formation for entire reaction = SUM of heat of formation of Products - (SUM of heat of formation of reactants)

Answer 18

summation just means to add

Answer 19

I assume Pb(s) is the lowest energy form of that atom so thus it would have a heat of formation of zero

Answer 20

so you only have 1 variable left

Answer 21

What do u do with the rest of the info bout Hf of CO2

Answer 22

–131.4 kJ = (–393.5 kJ/mol + x) - (–110.5 kJ/mol + 0)

Answer 23

There I spoon fed you it :) I have to go in about 5 minutes need to get back to actually studying. So please ask your questions now

Answer 24

oh btw x = heat of formation of PbO(s)

hope this helps please feel free to ask me anything else :)