Question about Casio FX-115MS Plus Calculator

1 Answer

How to find pka value

How do I find the pka value using my calculator. What buttons do I press?

Posted by on

  • Anonymous Mar 22, 2014

    calculate ph



1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Casio Master
  • 8,073 Answers

If I guessed right you are talking about the Chemistry notion of the pKa
Let the equilibrium constant be Ka =1.8x10^(-5). Then by definition pKa=-log(Ka) , log in base 10
pKa = - log(1.8x 10^(-5))
First set [MODE] to [COMP] by pressing [MODE] 1.
[LOG] [(] 1.8 [x] [SHIFT] [10 to the x] [(-)] 5 [)] . [(-)]
The [(-)] key is the change sign key : a small - between parentheses. The last [(-)] sign in the expression takes the negative of the whole calculation to obtain the correct value of the pKa.
The value you should find for the above exemple is 4.74

Hope it helps.

Posted on Sep 18, 2009

  • k24674 Sep 18, 2009

    Warning There is not dot before the last change sign symbol.
    [LOG] [(] 1.8 [x] [SHIFT] [10 to the x] [(-)] 5 [)] [(-)]



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

What is CPT on TI Calculator

"ComPuTe". On TI financial calculators you have to press the CPT button before pressing the button for the value you're solving for. (N, I, PV, PMT, or FV). On an HP calculator, you just press the N-I-PV-PMT-FV button without making any entry in order to solve for the desired value.

May 05, 2014 | HP 10bII Calculator

1 Answer

How to interpolate

Hi there,

In Stat mode (press MODE 1) choose the type of data you are working with, e.g linear or quadratic data.
Type in your data points by typing in the x-value pressing (x,y) button, the y-value and CHANGE.
Once you have entered all your data press the ON button.
If you want to predict or interpolate the x value given the y value, you need to type in the y-value and press 2nd F and the ( button. Do you see above ( there is an orange x'?
To predict the y-value, type in the given x-value and then press 2nd F and ) button. Again above this button in orange you will see y'.
If you would like the equation of the line you will see a blue a, b and c above the ( button, ) button and x button. Use the ALPHA to access these functions.

Apr 12, 2014 | Sharp EL-506 Calculator

1 Answer

TI-84 calculator clear data on x,T,n

Press [2nd][+] to open (Mem)ory management tool.
Select [2:Mem Mgmt,Del]
Press [2:Real]
Scroll down to reach X;
Press the DEL(ete) key.
The X-variable will disappear from the list. and the stored value will be replaced by 0.
You could also just use 0 [STO>][X,T,Theta,n] to reset value to 0

Feb 28, 2012 | Texas Instruments TI-84 Plus Silver...

1 Answer

To calculate the maturity yield I cant find the CPT on my hp10bll calculator nor can I find the I that they use to get the sum

The CPT button is used on the TI calculators to tell the calculator to compute the value instead of storing one. The HP calculator knows whether you just typed in a number or not, and so it can distinguish without the need for such a key. Thus to calculate a particular value after entering the others, you can simply press the key for that value without bothering with any CPT key.

As for the maturity yield, without knowing exactly which value you want, I'm afraid I can't tell you which key to press. Could you reply to this post and specify that? What key do "they" use on what calculator?

Jul 31, 2011 | HP 10bII Calculator

1 Answer

How to find slope with two point coordinates on ti-84 plus calculator

Assuming your two point coordinates are of the form (x1, y1) and (x2, y2).
There are two possible methods:
You can use the slope formula which is commonly known as "rise over run." To do this: slope = (y2 - y1) / (x2 - x1) This means that the vertical distance covered by the two points divided by the horizontal distance covered by the two points is equal to the slope.
You can use your calculator's linear regression capabilities:
First step: Press the STAT button (next to the arrow keys toward the top right of your calculator).
Second: Select the first option, Edit...
Third: Under L1, enter your first x value, press enter, enter your second x value, press enter again.
Fourth: Under L2, enter your first y value, press enter, enter your second y value, press enter again.
Fifth: Press the STAT button again. Press the right arrow button to highlight CALC.
Sixth: Select the fourth option LinReg(ax+b).
Seventh: Press 2ND then 1 (L1 should show up on your screen). Then press the comma button (right above the number 7). Press 2ND then 2 (L2 should show up on your screen). Press ENTER.
Eighth: Once you press ENTER, several values will appear. The a value is the slope of the two coordinates.

Feb 03, 2011 | Texas Instruments TI-84 Plus Silver...

1 Answer

I have a qustion that asks "what is e^1.8?' how do I use the e^x button on my Texas ti-30xa?

Put in the value and then press 2nd [e^x] to calculate e raised to that value. For example, to calculate e^1.8, press 1 . 8 2nd [e^x] =

Nov 01, 2010 | Texas Instruments TI-30XA Calculator

1 Answer

Please explain which buttons to push on TI-36x solar calculator to find the pKa of benzoic acid. the Ka for benzoic acid is 6.5 X 10 to the -5th ? (Sorry I don't know how to type the exponents for you)

You need the [EE] key to enter powers of 10 exponents.
You need the change sign key [+/-] key.
You need the [LOG] key.

pKa: 6.5 [EE] [+/-] 5 [LOG] [+/-]
There are two change sign: The first (either before or after the exponent 5), the last is entered after you press the log key , so as to negate (make negative if result is positive, and make positive is result is negative) the value.
The result should be 4.1870866 or 4.19

Mar 08, 2010 | Texas Instruments TI-36 X Solar Calculator

1 Answer

How to use the log function for acidity constants? I get a syntax error

Let Ka be the acidity constant (acid dissociation constant). The pKa is defined as the negative of the log in base 10 of the acidity constant.
pKa= - log_10(Ka) where log_10 is the logarithm in base 10.

To calculate the pKa you use the key labeled [LOG], just above [COS]. Be careful with the negative sign: For that, you use the key [(-)] just above the RCL key. Press the keys in the order specified below

pKa = [(-)] [LOG] number [ ) ] [=]

Although the right parenthesis is not required in this particular case, it is better to accustom oneself to close the parenthesis.

Hope it helps.

Dec 07, 2009 | Casio FX-115ES Scientific Calculator

1 Answer

What is the equivalent button for compute (CMT in my text), to use PV,FV,N,I/YR/PMT functions?

Unlike other brand calculators, HP calculators don't need such a key. After entering the other data, simply press the key for the desired value. For example, to find the future value, simply press the "FV" key.

Aug 09, 2009 | HP 10bII Calculator

Not finding what you are looking for?
Casio FX-115MS Plus Calculator Logo

3,633 people viewed this question

Ask a Question

Usually answered in minutes!

Top Casio Office Equipment & Supplies Experts


Level 3 Expert

8073 Answers

Les Dickinson
Les Dickinson

Level 3 Expert

18425 Answers


Level 3 Expert

2237 Answers

Are you a Casio Office Equipment and Supply Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides