Complete and balance each of the following equations for gas evolution reactions HCl(aq)+ZnS(s)>

2HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

Equalization of chemical reactions can be done using variables. Steps in equalizing the reaction equation:  

Reaction

HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

1. give equation

aHCl(aq) + bZnS(s) ⇒ ZnCl₂(aq) + cH₂S(g)

2. make an equation

H, left=a, right=2c⇒a=2c(eq 1)

Cl, left=a, right=2⇒a=2⇒c=1(from eq 1)

Zn, left=b, right=1⇒b=1

So the equation :

2HCl(aq) + ZnS(s) ⇒ ZnCl₂(aq) + H₂S(g)

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.