Please help me with this homework

Explanation:

Melting example:

Melting chocolate

Freezing example:

Freezing water to ice

Boiling example:

Water boiled in a kettle

Condensation example:

Steam from your bath/shower condenses onto the mirror

Hope this helps :)

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a

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