Question

You place ONE pot containing ALL of the following ingredients (representative of minerals in the Earth’s mantle) over a heat source (100˚F) for 2 minutes (not everything melts! Think about temperature.) Pour off what melted onto a plate (representative of the Earth’s surface). How would you describe the material (both physically and chemically) on the plate? How would you describe the contents remaining in the pot? What igneous process(es) would you witness? How would you relate this to chemical compositions of igneous rocks? (5 pts)

           

Ingredient	Melting Temperature (˚F)
Ice cream	40
Chocolate chips	90
Marshmallows	113
Peanut butter	150

Answer 1

Concept required- the igneous rocks are the rocks which are formed due to partial melting of rocks within the earth's crust and the mantle. Now let's see how this is related to the given question :0

Solution-

When the pot is heated at 100^o F, the materials having melting point less than or equal to 100 will melt down. So once we take out the contents of the pot, Ice cream, Chocolate chips would have melted down, while Marshmallows, Peanut Butter would still be solid ( Marshmallow will be , although, a little melty) So the material would be described as physically like a rock among sea water, ie some will be melted , and some are Solid, So the Solid Marshmallow, Peanut Butter will stand firm amidst the liquid ice cream and chocolate chips. Chemically they will be in a different phase.To get an idea, the picture will be more or like this

Once the contents are laid out on the Plate, the temperature is cooler than the pot. Thus the melted substance will now start to cool off. Naturally some will cool off at faster rate, will some will take long time to cool. So this is analogous to the Extrusive rock formation process (where the rocks cool and solidify quickly) and the Intrusive rock formation process (where rocks take more time to cool and solidify)

Based on this rock cooling process is dependent the chemical composition of the rock formed. If the rock cools off sowly (intrusive rocks), we will have coarse grained or crystallized/ non-crystallized rocks. For example granite. And if the rock cools off quickly, we get Fine-grained intrusive rocks. For example - Basalt.