How does the law of conservation of energy show the total energy in a system stays the same? plz answer the truth

Law of conservation states that energy in a isolated environment, this basically means that energy cannot be destroyed or created.

I'm citing a site that will give you some great examples and has a decent explanation

https://www.explainthatstuff.com/conservation-of-energy.html

here's the link to your question!

explanation:

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