Engineers are starting on a new project to develop technology. Which of these
statements does not describe something they might do at the very beginning
of the process?
O
A. Look at the problems society is facing.
O
B. Decide whether they have designed the best possible product.
O
C. Make a decision about how to best apply the technology.
D. Look at the benefits and challenges of using specific materials.
SUBMIT

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.

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