Exothermic gives off heat/energy and endothermic takes in heat/energy. Exothermic example: a candle flame
Endothermic example: baking bread
In Exothermic, you can expect the surrounding temp. to rise, and in Endothermic you can expect the surrounding temperature to fall.
Hope this helps
<span>Answer:
2Al(s) + 3Cl2(g) ---> 2AlCl3(s)
Always work in moles
moles = mass of substane / molar mass
2Al (s) + 3Cl (g) --> 2AlCl3 (s)
moles Al = 23.0 g / 26.98 g/mol
= 0.852 moles Al</span>
They have different ratios of elements. Water is H20 and Hydrogen Peroxide is H202. The extra oxygen atom in hydrogen peroxide causes it to be structured and react differently.