<span>3.68 x 10²⁵ bromine atoms * 1mol/6.02*10²³ atoms=
= 61.13 mol of bromine atoms
1 mol PBr3 ----- 3 mol Br
x mol PBr3 -----61.13 mol Br
x= 1*61.13/3 = 20.4 mol PBr3.
</span>20.4 mol PBr3 <span>contain 3.68 x 10^25 bromine atoms.</span>
Enthalpy is the change in energy. A cold pack will react endothermically and enthalpy will be positive and a heat pack will have negative enthalpy. You cannot determine which has more change in enthalpy unless you measure the temperature change. Eg. a heat pack went from 25c to 35c will have greater change in enthalpy then a cold pack going from 25 to 20c because the net temperature difference is greater
Comets are balls of ice and dust in orbit around the Sun. The orbits of comets are different from those of planets - they are elliptical. A comet's orbit takes it very close to the Sun and then far away again.
Potential energy is the energy stored. What do u think it is? (I don't really know)
