Two chemical reactions are shown: A. 2Mg + O2 -> 2MgO
B. CaCO3 -> CaO + CO2
Which statement is true? (5 points)
-Both are synthesis reactions.
-Both are decomposition reactions.
-A is a synthesis reaction, and B is a decomposition reaction.
-A is a decomposition reaction, and B is a synthesis reaction.

C. A is a synthesis reaction, and B is a decomposition reaction

Explanation:

Did the test and got it right.

i think so it’s will be b yes i believe its

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