## anonymous one year ago Determine whether the value of the gas constant R would be: a) higher, b) lower, c) cause no change if: Zn(s) contains contaminants that are insoluble with HCl solution (hint: follow a setup for the calculation of R to see the effect of each error)

1. anonymous

@Photon336

2. anonymous

So I started with the reaction: $$\sf Zn~(s) ~+~ HCl ~(aq)~\rightarrow ~ZnCl_2~(aq)~+~H_2~(g)~$$ the ideal gas law only applies to gasses, therefore setting up my ratio for R, I get, $$\sf R=\dfrac{P_{H_2}V_{H_2}}{n_{H_2}T_{H_2}}$$

3. anonymous

Does the contamination of zinc $$\mathbf {lower}$$ the actual amount of zinc reacting with the HCl?

4. anonymous

$\sf Zn~(s) ~+~ \color{red}{2}HCl ~(aq)~\rightarrow ~ZnCl_2~(aq)~+~H_2~(g)~$

5. anonymous

Contamination would lower the amount of zinc before the reaction or at the reaction.

6. anonymous

Ohhh, alright!

7. anonymous

And they're insoluble with HCl, which leaves a lighter zinc.

8. anonymous

Then how would using a lower amount of zinc effect the volume of $$\sf H_2$$ ?

9. Photon336

I agree with @Shalante

10. anonymous

Not 100% sure though.

11. anonymous

I would say Zinc+contaminants+HCl>> Zinc Chloride+Hydrogen gas+contaminants. Mass of Contaminants before=mass of contaminants after.

12. anonymous

Oh... the way I calculated it I think I might have done something wrong. I took the mass of zinc I had measured out, and converted that into moles, used PV=nRT to find the volume with the respective moles f zinc from the measured amount. Then I compared it to zinc with contaminants, but the mass of zinc with contaminants should have been lower, and not a higher amount I think.

13. anonymous

So.. i'll write out what I did.

14. anonymous

PV=nRT on a solid? (zinc)

15. anonymous

$\text{mass of zinc w/o contamin.} =0.1901~g~Zn$$\sf ~P_{H_2} =~0.961~atm~\\ V_{H_2}~=~?~\\ n_{H_2} = 0.1901~g~Zn ~\times~\frac{1~mol~Zn}{65.39~g~Zn} = 0.002907~mol~Zn$$\sf PV=nRT \\ (0.961~ atm)V_{H_2} =~ (0.002907~ mol)\left(\frac{0.0821~L ~atm}{~ mol~ K}\right) (295~K) \\ V_{H_2} = 0.0732~ L$

16. anonymous

Ack. nvm. I had to change to moles of $$H_2$$

17. anonymous

$\sf ~P_{H_2} =~0.961~atm~\\ V_{H_2}~=~?~\\ n_{H_2} = 0.1901~g~Zn ~\times~\frac{1~mol~Zn}{65.39~g~Zn}~\times~\frac{1~mol~H_2}{1~mol~Zn } = 0.002097 ~mol~H_2 ~$

18. anonymous

I did the same thing by increasing the g of zinc with contaminants, but i think that is wrong to do because it will give me a higher value volume of H2.

19. anonymous

Grams of zinc decreases with contaminants . That is my opinion.

20. anonymous

But zinc can be a contaminant lol. If zinc contains contaminants, it cant have more zinc. Either it stays the same or decreases. Thats what I think.

21. anonymous

yeah, the correct answer was that it $$\mathbf {lowered}$$ the value of the gas constant, which would only make sense if the $$\mathbf{volume}$$ of the $$\sf H_2$$ gas was $$\mathbf{decreased}$$ due to the $$\mathbf{decrease}$$ in moles of $$\sf H_2$$ produced by a $$\mathbf{decrease}$$ in the moles of contaminated Zn.

22. anonymous

Oh yeah, I mentioned that earlier and photon agree. Because I think contaminant is in some case can decrease an element by removing it through chemical reaction. Just like how soap kills bacteria, but contamination is the opposite.

23. anonymous

I only studied contamination in groundwater and the amount of contamination that adds up to it makes the water undrinkable due to lack to hydrogen and oxygen.

24. anonymous

I didnt realize my drawing was cut out. I used conservation of mass on a table earlier, but it was cut off. I didnt realize. It showed that the grams of hydrogen gas decrease in mass with contaminants

25. anonymous

Ahh I see I see. It makes sense now!

26. anonymous

Thank you @Shalante :)

27. anonymous

I might have some other questions later!

28. anonymous

Ok, I'll check it out later. See you soon.

29. anonymous

^^