Most of the heat that’s melting the ice comes from the foil. That’s because metals are good conductors of heat. Heat from the surroundings flows into the foil and then from the foil into the ice. Draw arrows to show the amount and direction of heat transfer between the foil and the ice.

listen, you cant how young you were.

"you didn't chose the stud life. the stud life chose you."

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