Which best describes an oxidizing agent?
a) a reactant that undergoes oxidation
b) a reactant that undergoes reduction
c) the product of an oxidation
d) the product of a reduction

B) a reactant that undergoes reduction

Explanation:

Oxidation reaction is defined as the reaction in which a substance looses electrons. The oxidation state of the substance increases during oxidation.

Reduction reaction is defined as the reaction in which a substance gains electrons. The oxidation state of the substance gets reduced during reduction.

Overall reaction:

The substance M which itself gets oxidized, reduces other and is called as reducing agent. The substance N which itself gets reduced, oxidizes other and is called as oxidizing agent.

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