At STP, which of the following would have the same number of molecules at 1 L of C2H4 gas? Assume that each behaves as an ideal gas. A. 0.5 L of H2 gas
B. 2 L of H2O gas
C. 1 L of Ne gas
D. 3 L of Cl2 gas

1L of Ne gas

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