A student is given 9.15x1015 formula units of ammonium sulfate, (NH4)2SO4, and is asked to determine the number of moles. How many moles are present in this sample? Be sure to round your answer to the correct number of significant figures. (This answer will have to be written in scientific notation. Here is an example with the format you should use to enter in your 2.5x102 = 2.5E2)

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