The compound diborane can be used as a rocket propellant. What is the percent composition of boron in diborane (B2H6)? Α.22%
Β.25%
C.39%
D.75%
E.78%

Explanation:

atomic weight of B= 10.8

atomic weight of h = 1.0

B2H6 = 2*10.81+6*1= 27.62

out of total 27.62 the Boron contrubtion was = 2*10.81= 21.62

For 27.62 B2H6   21.62 is B

for 100 B2H6  = 21.62*100 /27.62

                       = %

can you calcualte and the coorect answer ?

answer: enthalpy

explanation:

for a exothermic reaction, the energy is released i.e. the energy of the products is lower than the energy of the reactants.

= enthaply

= energy of products

= energy of reactants

as , thus comes out to be negative. negative value of enthalpy shows that the reaction is exothermic.

a). in this case, dh> 0 and sd> 0. if t becomes larger, the term "-tds" will become more negative. at some point, it is possible that -dts will be more negative than the dh is positive, and the reaction will become spontaneous. this is probably the correct answer, but you should look at all of the other possibilities and make sure of that.