When the equation H2 + Fe3O4 => Fe + H2O is completely balanced using the smallest whole numbers, the coefficient of H2 would be... Choices:
1). 1
2). 2
3). 3
4). 4

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock

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