Suppose you will determine the composition of the unknown substance that was collected at the scene of the crime. You are encouraged to work on this case. You can perform a series of tests on the unknown substance and compare results of the same tests performed on known samples. Follow these steps: List physical properties you can use as a simple method of identifying substances.

Describe how you can use density to help identify unknown substances.

Explain how forensic chemist can help you identify unknown substances.

How important is comparing tests results of know substances in a lab setting?

b   erergart

Explanation:

calculate how many grams of ammonia can be produced from 4.21 grams of

n2 + 3h2 = 2nh3

my answer:

25.0g n2 x (1 mol/ 28.0gn2) x (2 mol nh3/ 1 mol n2) x (17.0g nh3/ 1 molnh3) = 30.36g n2

25.0g h2 x (1 mol h2/ 2.00g h2) x (2 mol nh3/ 3 mol h2) x (17.0g nh3/ 1 mol nh3) = 141.67g h2

lr = n2

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.