| | [Chemistry] Chemistry Question |  |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
|  Subject: [Chemistry] Chemistry Question ![[Chemistry] Chemistry Question Icon_minitime](https://2img.net/i/fa/icon_minitime.gif) Mon Aug 04, 2008 10:00 pm | |
| An impure sample of zinc weighting 50.0g reacts with 129mL of HCL (35.0% w/w). If the density of the HCL solution is 1.18g/cm3, calculate:
(a) the molarity of the HCL solution used in the reaction.
(b) the percentage of zinc in the impure sample
The density of 10.5 molal NAOH solution is 1.33g/cm3 at 20 celsius. Calculate,
(a) mole fraction of H2O
(b) molarity of CH3OH
(c) Molality of CH3OH | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Mon Aug 04, 2008 10:01 pm | |
| 2NO + O2 ---> 2NO2 H<0
Draw an energy diagram to show the change in energy when No reacts with O2 to form NO2. Indicate clearly on your diagram the activation energy of each step in the mechanism. | |
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Admin
Admin~*~*
Posts : 232
Join date : 2008-07-23
| | Subject: Re: [Chemistry] Chemistry Question Wed Aug 06, 2008 1:57 am | |
| No ppl reply geh? LOL I am here to give some support........   | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Fri Aug 22, 2008 9:31 pm | |
| X + Y -> Z
The above reaction is first order with respect to X and zero with respect to Y. Initial Conc. of X: 1.50 mol dm^-3
Initial Conc. of Y: 2.00 mol dm^-3
Initial rate of reaction: 6.70 X 10^-5 mol dm^-3 s^-1
What is the rate of reaction after one hour??
*post the answer pls~~ | |
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mia
Posts : 63
Join date : 2008-08-01
| | Subject: Re: [Chemistry] Chemistry Question Sat Aug 23, 2008 12:28 am | |
|  are you testing us....? Seriously, I did try....  but I dunno how to do..... Where did you get the questions?? | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Sat Aug 23, 2008 1:09 pm | |
| from a friend..net friend | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Sat Aug 23, 2008 5:24 pm | |
| calculate the rate constant,
use the equation ln A = -kt + ln Ao , get final conc. of X, and
(Initial conc of X - final conc of X)/ 3600s
Ro =k x Ao
Rf =k x Af | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Tue Sep 16, 2008 8:09 pm | |
| Right here is another interesting question!!
What is the mass of potassium hydroxide ,KOH that must be added to 250 cm^3 of 0.10 moldm^-3 hydrofluoric acid , HF in order to obtain a solution with pH 3.3 ?
[relative atomis mass , H=1 ; O=16 ; K=39 ; Ka HF = 6.8x10^-4 ]
(gimme the working pls..coz honestly i really dunno how to do~~) | |
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withoutwax
Professor
Posts : 101
Join date : 2008-08-02
| | Subject: Re: [Chemistry] Chemistry Question Mon Sep 22, 2008 10:08 pm | |
| The equilibrium constant for the reaction
N2 (g) + 3H2 (g) --> 2 NH3 (g) is 4.0 x 10^-3 atm^-2 at 600 degree celcius. What is the pressure required to obtain a mixture containing 15% by volume of ammonia if the reaction starts with hydrogen and nitrogen in the molar ratio of 3:1?
A 7.4
B 8.9
C 10.1
D 13.2 | |
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