Indicate how your calculated NaOH concentration would be in error (is it higher, lower, or unaffected by the following details of the titration. In each case, explain your reasoning. a) You over-shot the end-point b) While titrating you noticed drops of solution clinging on the inner walls of the buret above the solution level c) You added ~10 mLs of water to the KHP solution while titrating d) You noticed an air bubble trapped in stopcock which is no longer present at end of titration. e) In placing the KHP solution under buret you spilled a little KHP solution on the bench.

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