A hot pack foot warmer contains iron powder, water, salt, activated carbon and vermiculite. It is activated by exposing the contents to air. Hot packs are used by hunters and other outdoor sports enthusiasts and workers where access to heaters or fires is not possible. Is this process endothermic or exothermic? Explain.
Vermiculite is an absorbent. It retains water and slowly releases it as the soil dries. So to make it simple, vermiculite helps to maintain an even moisture level in the potting soil so that you would not have to check your plants every 12 hrs. for signs of drying out.
They are both used to lighten soil to decrease compaction. Vermiculite is made of mica. Not sure about perlite composition. Some people start seeds in vermiculite. I mix Miraclegro potting soil (4 parts) with 1 part vermiculite, 1 part perlite, 1 part sphagnum moss. Great success growing all sorts of plants with the mixture.
Both are used to lighten the soil and keep it from compacting and allows the soil to drain so there is no problem with root rot. The roots find it easier to grow as the soil is a lot lighter. They retain a little moisture to help the soil
