This depends in what type reaction is occurring. It may be an endothermic reaction or an exothermic reaction. If the reaction is endothermic or heat is being absorbed by the reaction, then the forward reaction is favored or the products are being formed by the addition of heat. If the reaction is exothermic or heat is released by the reaction, then the backward reaction is favored or the reactants are being formed by the addition of heat.
The kind of magma that is found in the most explosive volcanoes, the composite volcanoes, is andesitic magma. It is magma that is quite high in silica content which makes it thick, sticky and gooey. Great lumps of this sticky magma cool at the top of the volcano to form a sealed cap. Magma beneath the cap builds up and pressure mounts and eventually becomes too much to be contained and the magma violently erupts out from the top, blowing out the cap and shooting miles up into the air and in all directions.
The kind of magma found in gentle volcanoes such as shield volcanoes is runny in consistency. It has very minimal amounts of silica and is not thick but loose. It therefore tends to trickle out of the top of the volcano rather than erupt or explode.
The reaction between iron and nitric acid eventually produces a red-brown rust colour (iron(III) oxide). could link this with corrosion and acid rain
