Calculate the mass of ZnCl formed when 30g of Zn is reacted according to the following equation:
___ Zn + ___ HCl ___ ZnCl + ___H 2

62.7g ZnCl2

Explanation:

Zn+ 2HCl = ZnCl2 + H2

Atomic mass of Zn is 65

Atomic mass of Cl is 35.5

Atomic mass of H is 1

Molecular mass of ZnCl2 is {65+(35.5×2)}= 136

So,

65g of Zn produce 136g of ZnCl2

1g ofZn produce( 136÷65)gZnCl2

= 2. 09g

30g ofZn produce (2. 09×30)

=62.7g ZnCl2

the mass of ZnCl2 is 62.7g when 30g of Zn is reacted .

"standard molar enthalpy:

h2o ( liquid water ) : - 285.8 kj/mole

h2o ( water vapor ) : - 241.8 kj / mole.

δhrxn = - 241. 8 - ( - 285.8 )= -241.8 + 285.8 = 44.0

answer: 44.0 kj"