Combustion, or , is an example of one of the most familiar chemical changes. melting of ice, likewise, is one of the most common examples of physical changes. when a piece of coal burns, combines with the carbon in the coal. the products are carbon dioxide gas, water vapor, and a lot of ash. after careful measurements are taken, the of the reactants (coal and oxygen) is to the mass of the products (carbon dioxide, water vapor, and ash). during the reaction, the quantity of matter is unchanged. similarly, when 10 grams of ice , grams of water is obtained. mass is in this change as well.'

Why doesn't heat added to water make the tempature rise above 100c

Straightforward questions answered in the powerpoint slidesreaction: heating the starting materials under refluxwhat does it mean to heat under reflux? why do we choose water as the reflux solvent? what are boiling chips used for? why do we put a condenser on top of the reaction? why do we add heat and let the reaction stir for 30 minutes? why do we add sulfuric acid to the reaction after it cools as opposed to when it’s still hot? separation: filtration of precipitatewhy don’t we do an aqueous and organic extraction in the separatory funnel? why do you rinse the salicylic acid on the filter with ice cold water? purification: recrystallization of salicylic acid (no hot filtration needed)what is the difference in the amount of room temperature water vs. boiling water needed to dissolve the salicylic acid (assume a 1.2 gram yield of salicylic acid)? remember, in the lab if you need x ml of boiling water to dissolve a solid, then you should add a little more (definitely no more than 1.5 times the theoretical amount) to ensure it doesn’t recrystallize prematurely. analysis: melting point of salicylic acidwhat can you conclude if the melting point of the salicylic acid you just synthesized is 152-155oc and the 1: 1 mix of your product and “synthetic” salicylic acid is 151-154oc?

Draw the skeletal structures of two different molecules that are each made of 5 carbon atoms and 12 hydrogen atoms.