conservation of matter Zinc metal reacts with acid solution to produce hydrogen

Question

conservation of matter

Zinc metal reacts with acid solution to produce hydrogen gas and zinc ion as follows, Zn (s) + 2H^+ (aq) rightarrow Zn^2+ (aq) + H_2 (g) You add 6.825 grams of Zn metal to 29.0 mL of 1.70 M HC1, and catch the hydrogen in a balloon as in the following picture. How many moles of Zn have you added to the flask? How many moles of H^+ are in the solution? How many moles of Zn will have reacted with the H^+ when the reaction is complete? How many moles of Zn will remain unreacted? What mass of Zn will remain unreacted? How many moles of H_2 gas will be produced? What mass of H_2 gas will be produced? Assuming that one mole of H_2 gas would occupy a volume of 22 L at the temperature and pressure in the balloon, what would be the volume of the balloon?

Explanation / Answer

Atomic weight of Zn= 63.58

1.Moles of Zn= Mass/ Atomic weight= 6.825/63.58 =0.1073

Moles of HCl in 1.7M and 29 ml =1.7*29/1000= 0.0493

2 mloes of HCl ionizs to give 2HCl---> 2H+ 2Cl- 2 moles of H+

0.0493 moles of HCl gives 0.0493 H+

3. The reaction is Zn+2HCl ----> ZnCl2+H2

mole of Zn requires 2 moles of HCl

Stoichiometric ratio = 1:2 given reactants ratio = 0.1073 :0.0493 = 1: 0.493/0.1073 =1:0.4592

HCl is the limting reactant

2 moles of HCl requires 1 mole of Zn

0.0493 moles of HCl require =0.0493/2 =0.02465 moles

4.Moles of Zn unreacted = initial moes- reacted moles =0.1073-0.02465=0.08265

5.Moles of H2 produced = moles of Zn consumed =0.02465

6.Mass of H2= 2*0.02465 =0.0493 gms

7. 1 mole occipoes 22.4 L

0.02465 occupies 0.02465*22.4 L =0.55216 L

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