Question

How many grams of methane gas (CH4) are in a 15.8 liter sample at 1.2 atmospheres and 27°C? Show all work used to solve this problem

Answer 1

PV=nRT

Answer 2

can you use it?

Answer 3

on your own i mean

Answer 4

I have no idea what that means

Answer 5

its a formula for ideal gases

Answer 6

PV= nRT
p- pressure
V- volume
n- mole
R- constant
T- temperature

Answer 7

so what are you given in the question ?

Answer 8

I don't know, I know we have 15.8 liters

Answer 9

so ur volume 15.8 L

Answer 10

pressure is also given

Answer 11

and temperature

Answer 12

so
P= 1.2 atm
V= 15.8 L
T= 27 °C

Answer 13

you need to change units
for pressure change it from atm to Pa
for volume change it from L to m3
for temperature change it from °C to Kelvin

Answer 14

can u do that?

Answer 15

If you tell me how haha

Answer 16

lol okay

Answer 17

atm to pascal you need to multiply by 101 325

Answer 18

L to m3 you need to divide by 1000

Answer 19

and °C to Kelvin you need to add 273

Answer 20

now do it and tell me the new values

Answer 21

Where did you get these numbers?

Answer 22

this is conversion

Answer 23

you need to learnt how to change units

Answer 24

So the new temperature is 300?

Answer 25

yes :D

Answer 26

and the new volume is 0.0158?

Answer 27

thats right :)

Answer 28

And I don't understand the atm one, you have two numbers next to each other

Answer 29

come again? what do u mean 2 numbers next to each other?

Answer 30

How do I convert atm to whatever I'm supposed to convert it to

Answer 31

what is the value for atm?

Answer 32

1.2

Answer 33

good so if 1 atm = 101 325
1.2 atm= ?

Answer 34

I don't know what 101 325 means are you missing a comma or something

Answer 35

1 atm = 101 325 Pa
its number...

Answer 36

https://www.google.ae/webhp?hl=en&tab=Tw&gws_rd=ssl#hl=en&q=atm+to+pa

Answer 37

101.325 KPa
Change the Celcius to kelivin

Answer 38

she did.

Answer 39

so it'll be 1.2*101 325 =

Answer 40

that's so confusing, 121590?

Answer 41

yes

Answer 42

so
now your new values
P= 121590 Pa
V= 0.0158 m3
T= 300 K

Answer 43

right?

Answer 44

Right

Answer 45

you have to know that R is constant and the value of R is 8.31

Answer 46

get it?

Answer 47

Okay

Answer 48

cool so the formula we'll be using is
PV=nRT

what you don't have?

Answer 49

So basically pressure x volume = R x temp?

Answer 50

yes but don't forget 'n'

Answer 51

pressure*volume= mole*R*temperature

Answer 52

n means mole?

Answer 53

yes

Answer 54

so we don't have mole right?

Answer 55

Okay so pressure*volume = 18.96?

Answer 56

okay first can u make mole as subject?

Answer 57

I don't know what that means

Answer 58

for example if i want to find V , i'll make it as subject and the formula will look like this
V= nRT/P

Answer 59

So I'm looking for n = something?

Answer 60

yes

Answer 61

so if u make n as subject how the formula will look like?

Answer 62

n = R*temperature ?

Answer 63

how about volume and pressure?

Answer 64

What about it?

Answer 65

your main formula is
PV= nRT

Answer 66

Okay

Answer 67

so if u make n as subject
it'll be like this

n= PV/RT

Answer 68

do u understand?

Answer 69

Okay

Answer 70

now put the values into the formula and get your mole

Answer 71

So n = 1921. 122/2493
= 0.770 ?

Answer 72

yup :) 0.77

Answer 73

good job :)

Answer 74

now u found mole

Answer 75

can you tell me what is the formula of mole?

Answer 76

Mass/molecular mass?

Answer 77

good :)

Answer 78

what is the question asking you to find?

Answer 79

how many grams of CH4 are in a 15.8 liter sample at 1.2 atmospheres and 27°C?

Answer 80

so they are asking for Mas right?

Answer 81

mass*

Answer 82

Yeah they are

Answer 83

mole= mass/Mr
make mass as subject

Answer 84

I'm not good at that haha but mass = Mr/n?

Answer 85

no
mass= Mr*mole

Answer 86

now what is Mr of CH4?

Answer 87

That was my next guess, really quick Mr is what?

Answer 88

Mr is molecular mass

Answer 89

Okay where do I find it is it on the periodic table?

Answer 90

yes

Answer 91

16.04 g/mol

Answer 92

yeah basically 16

Answer 93

Okay so mass = 16 x 0.770
= 12.32

Answer 94

yup :D

Answer 95

done :)

Answer 96

Now what or are we done?

Answer 97

Yay! Do you mind if i write my answer in paragragh form and than I'll tag you in it and you can tell me if it looks good?

Answer 98

okay np :)