2. What is the concentration in percentage by mass when 18.0 grams of KNO3 is dissolved in 150 grams of
water?

%HNO₃ = 10.3%

Explanation:

%KNO₃ = (mass KNO₃/mass water + mass KNO₃)100%

=> (18.0/150+18)100% = 10.7% by weight

sorry i was late, but i don't know what assignment your talking about, i'm in flvs as well, im in earth space science. but u are behind pace bc every class should be in the 3's or 4'

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.