Question

In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B.

2A->3B

How many molecules of substance B are produced when 29.7g of substance A reacts? The molar mass of substance A is 28.8 g/mol.

Step 1: Convert the mass of A to moles.

Step 2: Convert the number of moles of A to the number of moles of B.

Step 3: Convert the number of moles of B to molecules of B.

Answer 1

mass of A = 29.7 g
molar mass of A = 28.8 g/mol
number of moles of A = mass /molar mass
                                      = 29.7/28.8
                                       =1.03125 mol
Moles of B formed = (3/2)*number of moles of A
                                  =(3/2)*1.03125 mol
                                   =1.546875 mol
Number of molecules of B = Moles of B * AVogadros number
                                             =1.546875*(6.022*10^23)
                                              =9.32*10^23 molecules
Answer: 9.32*10^23 molecules