Please Help! John collected the following volumes when doing a titration experiment: 24.30 mL, 24.35 mL, 24.70 mL, 24.00 mL, and 24.60 mL. The actual volume for the titration required to neutralize the acid was 24.50 mL. Would you say that John's data was accurate? Precise? Both accurate and precise? Neither accurate nor precise? Explain.

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