Stoichiometry and all its horribleness. Please help!!?

Question

If 48.7 g CS2 are burned in oxygen gas to produce carbon dioxide and sulfur dioxide, how many liters of sulfur dioxide gas are produced at STP?

Can you tell me how to setup and balance the equation?? An perhaps how to solve this.

Answer 1

Start with the balanced equation

CS2 + 3O2 --> CO2 + 2SO2

Then all we need are a few conversion factors to take us from grams of CS2 to liters of SO2 at STP:

48.7 g CS2 x (1 mol CS2 / 76.2 g CS2) x (2 mol SO2 / 1 mol CS2) x (22.4 L SO2 / 1 mol SO2) = 28.6 L SO2

=========== Follow up ===========

Without being rude, I think that Fanatic may be a bit frantic.  I would say her solution is bordering on overkill.

Answer 2

CS2     +    O2          ----> CO2     +     SO2

Now try balancing 4 O = 2O

2 S = 1S

1 C = 1 C

now you need to make each equal

CS2             +     3O2          ----> CO2     +    2SO2

m = 48.7 g

M = 46 g/mol

n = m/M = ____ moles

Now you need to use stochiometry to find SO2 moles, the best way is to look at units...

CS2             +     3O2          ----> CO2     +    2SO2

m = 48.7 g

M = 46 g/mol

n = m/M = __x__ moles              

calculate x

n required of

SO2 = _x_ moles  of  CS2<-- calculated * 2 moles S2/1 CS2

         = y moles

notice how i have CS2 in the denominator and numerator so that can cancel out and i can have moles of CS2 in the numerator. 2 is co-efficient of S2 and 1 is co-efficient of CS2 from the balanced equation

Now for this y moles...you want to find litres at STP and its a gas

you can use the ideal gas law and since its at STP

Temperature = 273 K, P = 1 atm

pV = nRT

1 atm * V  =  (y moles calculated) * R * 273 K

R is a constant  0.08205746  L·atm·K−1·mol−1

now you can calculated your V

Phew! Hope this helps :)