12. Which property of a mixture could be used to tell the difference between a container of salt water and a container of distilled water?
A. A mixture is not uniform.
B. A mixture contains more than one identifiable particle.
C. A mixture looks different than the pure substances from which it is made.
D. A mixture has different melting and boiling points than the pure substances
from which it is made.

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

answer would be option a) they have mobile charged particles.