The heat of fusion for a substance is 122 joules per gram. how many joules of heat are need to melt 7.50 grams of this substance at its melting point?

915 Joules

1 g = 122 Joules

7.5 g = ?

       = 122 × 7.5

      = 915 Joules

Thus, 7.5 g of the substance at its melting point will require 915 Joules of heat to melt.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.