What mass of hydrogen gas is produced when a 7.35g chunk of zink dissolve in 500 ml of 1.2 m hcl?

Answer 1

ZnS + 2 HCl --> Zn2+ + 2Cl- + (H2S)gas

Be careful!Almost 13 Litre of very toxic gaseous (or poisonous and stinky) hydrogen sulfide (H2S, gas) will be produced.

Only to be performed in absolutely approved and controlled laboratory conditions with a alkaline gas-scrubber !

Remember: H2S is already poisonous when you can't even smell it.

(Its MAC-dose concentration is lower than its odour threshold)

Stoichiometric calculus:

56.5 (g ZnS) / 97.474 (g/mol ZnS) = 0.5796 mol ZnS =

= 0.5796 (mol ZnS) * (2 mol HCl / mol ZnS) = 1.16 mol HCl

How many millilitres you'll need depends on the concentration HCl (in mol/L = mmol/ml ):

1.16*103 (mmol HCl) / 7.0 (mmol/ml HCl) = (1.16*103 / 7) = 166 ml HCl

Answer 2

Zn + 2HCl ---> H2 + ZnCl2

n = 0.112

mw = 65.39

g = 7.35

From these values (they are for the zinc), you can see that only .112 mol of Zn reacted.

To find the number of moles of HCl, we use n = cV.

n = 1.2 x 0.5

= 0.6 x 2 mols

= 1.2 mol HCl.

From this we can see that zinc is the limiting reagent and that 0.112 mol of H2 gas was produced.

g = mw x n

g = 2.016 x 0.112

= 0.225792 grams.

Answer 3

1. 15.0 mol HCl

Answer 4

.673M