How many grams of Br2 are needed to form 67.1 g of AlBr3 ?

2Al(s)+3Br2(l)⟶2AlBr3(s)

Approximately .

Explanation:

Look up the relative atomic mass of and on a modern periodic table:

Calculate the formula mass of and :

.

Calculate the number of moles of formula units in of :

.

Refer to the balanced equation for this reaction. The ratio between the coefficients of and in that equation is three-to-two. That corresponds to the ratio:

.

It is already calculated that approximately of was produced through this reaction. Apply this ratio to approximate the (minimum) number of moles of that is consumed:

.

Calculate the mass of that of :

.

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.