(Link; https://www. chemteam. info/SigFigs/SigFigsFable. html) 1. Why did the student's measurement turn out to be so costly?

2. What should he have done differently?

3. Real-world application: Why do you think it is important to use significant figures when recording a measurement? Hint: Think about how significant figures could impact the soda industry, sports, medicine, video games, toy construction, etc.

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