In a chemical reaction, the number of moles of the reactants A.
should always be equal to the number of moles of the products.
B.
depends on the amount of product that is formed.
C.
should never be equal to the number of moles of the products.
D.
may or may not be equal to the number of moles of the products.

may or may not be equal to the number of moles of the products.

Explanation:

A chemical reaction involves the interaction between reactants to yield products. The number of moles of reactants and products in the system depends on the stoichiometry of the reaction.

The balanced reaction equation shows us the number of moles of reactants and products involved in the reaction.

Hence, in the balanced chemical reaction equation; the number of moles of reactants may or may not be equal to the number of moles of the products.

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