PLZ I NED HELP

2h+02=h20

Explanation:

2 in front of h on left side

2 in front of h on right side

Explanation:

1. __1___ Fe + __1___ S → __1___ FeS. 2. __1___ H2 + __1___ Cl2 → __2___ HCl. 3. __2___ Mg + __1___ O2 → __2___ MgO. 4. __1___ O2 + __2___ H2

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