Because when ths shape of a sunstance changes , its physical appearance changes .A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.
<span>q(rxn) = - [q(water)+q(bomb)]
q(rxn) = -{[ (1000g)(4.184)(5.0)] + [ (5.0)(0.10)]}
q(rxn) = - (20920 + 0.5)
Now we divide 3.5g
q(rxn)= - (20920)/(3.5g)
q(rxn) = 5977.14
And final answer, change is to Kilo joule unit
-q(rxn) = 5.23 KJ/unit</span>
