For #2 of week 3 on achieve I know that since the ka value is above the 10^-4 we are not able to do the assumption, so how are we supposed to find x? I know we have to use the quadratic formula, but I keep getting stumped on it :/
Any help would be greatly appreciated!
Here is my ka equation for reference: 8.03 x 10^-3 = x^2/ .163-x
Achieve #2
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Re: Achieve #2
For your equation: 8.03 x 10-3= x2/ (0.163-x)
You first rearrange it:
x2=8.03 x 10-3 * 0.163- 8.03 x 10-3*x
x2+8.03 x 10-3*x-1.31 x 10-3 =0
Here, a=1, b=8.03 x 10-3, c=1.31 x 10-3.
Sub in the quadratic formula to get an answer for x.
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And another method with TI-84.
Plot a graph with "y=" button, type in y = x2/ (0.163-x)-8.03 x 10-3.
Click "graph" button.
Click "2nd" and then "trace".
Choose "2:zero".
Set a boundary and fill x that makes y=0. And you get your answer.
Hope this helps.
You first rearrange it:
x2=8.03 x 10-3 * 0.163- 8.03 x 10-3*x
x2+8.03 x 10-3*x-1.31 x 10-3 =0
Here, a=1, b=8.03 x 10-3, c=1.31 x 10-3.
Sub in the quadratic formula to get an answer for x.
---------
And another method with TI-84.
Plot a graph with "y=" button, type in y = x2/ (0.163-x)-8.03 x 10-3.
Click "graph" button.
Click "2nd" and then "trace".
Choose "2:zero".
Set a boundary and fill x that makes y=0. And you get your answer.
Hope this helps.
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- Posts: 108
- Joined: Fri Sep 24, 2021 5:49 am
Re: Achieve #2
When you have the equilibrium equation set up, rearrange it so that every term is on the same side and it is set to be equal to "0". Then apply the quadratic formula or use graphing calculator. For graphing calculator (TI-84 Plus CE model), press "apps" button --> press the number "9" --> press "enter" --> press the button "graph" for next --> enter your numbers for the quadratic equation and it calculates the zeros for you. Remember to only use the positive value.
Otherwise you have to solve the quadratic by hand.
Otherwise you have to solve the quadratic by hand.
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- Posts: 103
- Joined: Fri Sep 24, 2021 5:08 am
Re: Achieve #2
I'm also having trouble with #2. I was given "The Ka of a monoprotic weak acid is 0.00236. What is the percent ionization of a 0.191 M solution of this acid?" I made an ICE Table and I think I correctly found X to be 0.02008387547 using the quadratic formula, but I'm having trouble finding the percent ionization. I subtracted that from 0.191 to find HA. Then, I divided X by that value of HA and multiplied by 100% to find 11.75. However, my answer is wrong. Does anyone know if that work is incorrect?
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