Which of these reactions can be classified as double replacement reactions?

a) zn + 2hcl → zncl2 + h2

b) 2nacl + f2 → 2naf + cl2

c) 2albr3 + 3k2so4 → 6kbr + al2(so4)3

d) 2k + mgbr2 → 2kbr + mg

the answer is the

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