Agas with an empirical formula c2h2o has a molecular weight of 120.6g/mol. a possible molecular formula for the gas is a) ch2o b) c2h2o c) c3h6o1.5 d) c6h6o3 e) c4h4o2

M(C2H2O)= 12.0*2 +1.0*2 +16.0 = 42 g/mol is a molar mass for empirical formula.

120.6g/mol/42g/mol ≈ 3

So, empirical formula should be increased 3 times,

and molecular formula is C6H6O3.

Answer is D.

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol