please need help asap with chemistry question?

Methanethiol (CH4S) has a disagreeable odor and is often a component of bad breath. When methanethiol is burned, the sulfur reacts with oxygen to form SO2.

steps for solving “stoichiometric” problems like this one. MEMORIZE them!!!!!

1) write a balanced equation
2) convert everything given to moles
3) determine limiting reagent
4) convert moles limiting reagent to moles other species
5) convert moles back to mass. this is theoretical mass.. aka theoretical yield
6) % yield = actual recovered mass / theoretical mass x 100%

the idea being the coefficients of the balanced equation are in MOLE ratios. so if you know those coefficients (by writing a balanced equation) and convert everything to MOLES, they you can use the coeffients to convert between moles of the different species..

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example..
“how many grams of H2O can be formed by the complete combustion of 4 grams of H2?”

see if you can id the steps I outlined above…

2 H2 + 1 O2 —> 2 H2O

4 g H2 x (1 mole H2 / 2g H2) = 2 moles H2

complete combustion means O2 is in EXCESS. so H2 is limiting reagent

2 moles H2 x (2 moles H2O / 2 moles H2) = 2 moles H2O

2 moles H2O x (18g H2O / 1 mole H2O) = 36g H2O

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give it a try.. I’ll check back later

Any chemists out there? Would bad breath weigh more than fresh breath?

(would there be more sulphur in the gas mix with bad breath, and if so, would that make it heavier?)

Sulfur is only one possibility – as are amines (throw up smell) and ketones (fruity but disgusting.) Sulfur is a natural product of the breakdown of protein. CH4 (methane) does not smell, nor does H2S (hydrogen sulfide), though other compounds do.

Fresh breath is what? Oxygen, CO2, N2, H2O? Probably bad breath would weigh a bit more, but the difference would be negligible.