Question

SOMEONE PLZ HELP!!!! CALCULATE THE MASS(KG) OF WATER PRODUCED FROM THE COMBUSTION OF 1.0 GALLON (3.8L) OF GASOLINE(C8H18). THE DENSITY OF GAS IN .79 G/ML.

Answer 1

ok start by writing combustion reaction, then we will continue...

Answer 2

ok i thin kit is C8H18(l) +O2(g) = H2O(l) ?

Answer 3

did i get the states of the compounds right?

Answer 4

nope thats not right...
C8H18 + O2 -> CO2 + H2O
now is that equation ok like that (dont get in to states...)

Answer 5

ok thank you so now whats next

Answer 6

well we don't care how much CO2 is being produced ...it is just important to note all the H in C8H18 goes into H2O.

Answer 7

use unit analysis to get the answer....

Answer 8

ok so now in order to figure out the mass of the water produced what information would i look at

Answer 9

you start with 3.8 L C8H8 ... convert that into kg

Answer 10

then to kg of water?

Answer 11

or do u multiply kg of gas by density of gas?

Answer 12

\[3.8 l\ C_8H_{18} \times {.79 kg\ C_8H_{18} \over l\ C_8H_{18}}\] kg of C8H18

Answer 13

density of gas = mass of gas / volume of gas

Answer 14

then you want to get how much of that mass is Hydrogen

Answer 15

oh then from mass of H to mass of H2O

Answer 16

and also kryten wrote a chem equation above can you check that to see if its correct?

Answer 17

cuz he said you dnt have to worry about the states of the compounds in the reaction...is tht only for precipitation reactions you have to worry about tht?

Answer 18

you dont have to worry about states because you dont have to calculate anything state related example combustion energy or enthalpy etc.

Answer 19

\[3.8 \cancel{l\ C_8H_{18}} \times {.79 kg\ C_8H_{18} \over \cancel{l\ C_8H_{18}}} \times {18\ kg\ H \over114\ kg\ C_8H_{18}}\] ... 114 is the Molecular mass of C8H18 out of which 18 comes from H

Answer 20

this gives you the mass of hydrogen in kg that you are using to make the water ... you just need to convert it into the mass of water

Answer 21

so you would divide by atomic mass for water?

Answer 22

\[3.8 \cancel{l\ C_8H_{18}} \times {.79\ \cancel{kg\ C_8H_{18}} \over \cancel{l\ C_8H_{18}}} \times {18\ kg\ H \over114\ \cancel{kg\ C_8H_{18}}} \times {18\ kg\ H_2O \over 2\ kg\ H}\]

Answer 23

...the atomic mass of water divided by the amount that comes from water.

and there's your answer. :)

Answer 24

how did u get 18kg h2o

Answer 25

i mean how did u know

Answer 26

molar mass

Answer 27

Hydrogern mass = 1
Oxygen mass = 16
H2O = 18 .... out of which 2 comes from hydrogen

Answer 28

for density of C8H18 i used kg/L which is the same as g/ML.

multiply all those numbers and i got ~4.3 kg of water

Answer 29

THANK YOU SO MUCH FOR ALL YOUR HELP