A molecule has sp3d2 hybridization with 1 lone pair. ... The electron pair geometry of this molecule is: octahedral ... The geometry of this molecule is: octahedral . ... This molecule will have approximate bond angles of (If more than one bond angle is possible, separate each with a space.):

electron pair geometry - octahedral

molecular geometry - square pyramidal

bond angle - < 90 degrees

Explanation:

According to Valence Shell Electron Pair Repulsion Theory (VSEPR), The shapes of molecules depend on the number of electron pairs on the outermost shell of the central atom in the molecule. Recall that electron pairs are always positioned as far apart in space as possible to minimize repulsion.

For a molecule in sp3d2 hybridization, the expected electron domain geometry is octahedral. However, the presence of a lone pair in the molecule distorts the electron pair geometry away from the expected octahedral shape giving a molecular geometry of  square pyramidal and decreases the bond angle less than the expected 90 degrees.

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