Question

when 50ml of gas of at 45 degrees celcius and 0.55atm is placed into 250ml flask the temperature is 32 degrees celcius, what is the new pressure?

Answer 1

PV=nRT use it

Answer 2

i dont know where to put what

Answer 3

i assume number of moles of gas is constant

Answer 4

\[ \frac{ P _{1} V _{1} }{ T _{1} }=\frac{ P _{2} V _{2}}{ T _{2} }\]

Answer 5

there we go :D thanks! :)

Answer 6

:D YW

Answer 7

oh theres one more

Answer 8

noooooooooooooo jk ;)

Answer 9

When 0.60 grams of H2 are places into 2500.0 ml flask with an undisclosed amount of Bromine(+2), the total pressure is 12.5atm. if the temperature is 27 degrees Celsius, how many grams of bromine are in the flask?

Answer 10

apparently im supposed to use more than just one gas law

Answer 11

again i think you have to use PV=nRT

Answer 12

you have, P,. you have to find n that is number of moles, you have temperature, you have gas constant that is R and you have volume just plug in and play :D

Answer 13

yea but im supposed to use more than one law

Answer 14

PV=nRT is just one law and earlier i made the comparison from one law in two cases

Answer 15

okay can you explain what this formula is:\[[P_{ob}+a\left({n\over V}\right)^2]\times(v-nb)=nRT\]

Answer 16

this is the general case of PV=nRT when your a and b=0 we get PV=nRT, hope you know what does a and b stands for

Answer 17

lol, i dont

Answer 18

awesome ;) google it :D lol

Answer 19

n--> number of moles

Answer 20

a and b are either determined empirically for each individual compound or estimated from the relations.

Answer 21

i looked it up n now im even more confused..this is not helping :(

Answer 22

\[a=\frac{ 27R^2T _{c}^2 }{ P _{c} }\]

Answer 23

and \[b=\frac{ RT _{c} }{ 8P _{c} }\]

Answer 24

Tc , Pc--> critical temperature and pressure

Answer 25

question! the Volume in PV=nRT has t be in liters, right?

Answer 26

umm yea

Answer 27

u dont seem sure..?

Answer 28

its been 5 years since i did it for the last time lol so kinda but generally you should use SI units so i think you can use liters or in this case go with ml , in physical chemistry we prefer ml

Answer 29

okay well i figured that i need to find the pressure of H2 and subtract it from the total then use that left over pressure to calculate the moles of Br n convert that to grams to find grams...yea?

Answer 30

yep :D if you have number of moles use \[n=\frac{ w }{ m }\] where w--> weight andn m--> molar mass

Answer 31

okay well can you work it out with me? im not getting the right answer for some reason :S

Answer 32

what is your number of moles?

Answer 33

0.3 for H2

Answer 34

then just plug in the values

Answer 35

i did \[P_{H_2}(2500)=(0.3)(0.08206)(300)~~\implies~~P_{H_2}=0.00295416\]\[12.5-0.00295416=12.49704584\]\[(12.49704584)(2500)=n(0.08206)(300)~~\implies~~n_{Br}=1269.096377\]and i know that's not right, given the balance equation \(Br_2+2h_2\rightarrow2BrH_2\)

Answer 36

@ghazi

Answer 37

if you use liters though, it gives 0.97 moles which is 77.45 grams...i have no idea what to go by..??

Answer 38

use liters

Answer 39

whenever you have wrong answer try to check if your answer is reasonable or not

Answer 40

thats what im trying to make sure of..

pressure of H2=2.954atm
pressure of Br=9.56atm

moles of H2=0.3mol
moles of Br=0.97mol

grams of H2=0.60g
grams of Br=77.45g

reasonable??

Answer 41

yea this seems reasonable :)

Answer 42

the question is worth 6pts out of 12...i cant afford it being wrong :P

Answer 43

so i hope you got right :)

Answer 44

k thanks a lot! :D

Answer 45

:D