An unknown substance in aqueous solution is treated with various reagents including hexane, a colorless liquid less dense than water. The test tube is stoppered and shaken. The upper layer remains colorless. name two nometal species that cannot be present in the unknown

Chlorine and bromine

Explanation:

The chlorine and bromine in the answer may in form of chlorine water solution or bromine water solution.

When halogen generally are tested with hexane, it gives a characteristic colour. The color of chlorine is yellowish green. But with a greenish tinge and the color of bromine reddish but with an orange tinge. Iodine gives violent colour.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g