Which of the following accurately describes the ph scale?
a. the lower the ph is, the more basic the solution is.
b. the greater the concentration of hydroxide ions, the higher the acidity is.
c. the greater the ph is, the lower the acidity is.
d. the lower the concentration of hydrogen ions, the higher the acidity is.

what is the question?

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