We did a styrofoam lab to see what hydrides look like when you move across a period. I wanted to know if I drew the last model correctly for group 15. The directions were confusing. I’m supposed to draw the small yellow circles for the hydrogen and the lines represent valence electrons.

Please help me it would be greatly appreciated:)

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