Hi,
Can any1 help with theses questions. I need to solve these because there will be similar questions on the midterm for me, coming week. Btw I have tried few.
1. How many milliliters of a 15.0%, by mass solution of KOH (Aq) ( d= 1.14g/mL ) are required to produce 27.0 of a solution with pH= 11.45?
Answer is required in mL. Liters is just as fine as mL :P
50.00 mL of 1.45×10−2 M HI(aq) is mixed with 85.00 mL of 1.10×10−2 M KOH (aq).
Above is the data given which is required to solve Q2:
Q2:- What is the of the final solution?
Q3:- What is the pH of an aqueous solution that is 0.124 M NH4Cl?
Thanks in Advance for answering the questions, plz provide the solution if possible?
We will be happy to critique your work, or thinking. We aren't going to do your tests for you.
But these questions were never taught in the class and they are appearing on the mid-term.
ok, here is the thing. I have tried other questions and got the right answer :P
But for question # 2 I convert the ph to pOH and den find the OH-
den I find the # of moles from 6.8% ammonia and den I use the Kb value of ammonia to find the OH- in the 6.8% ammonia and using dat concentration I use the formula c1v1=c2v2 to get the volume which will be required to dilute the 0.625L of pH=11.65?
But I am getting an answer of 334mL which I am told is WRONG.
So plz can some1 tell me what am I missing or doing wrong.
PIEASE TELL ME HOW MANY MAKES THE QUESTION
Sure! I'll be happy to help with your questions. Let's go through them one by one and I'll explain how to solve them.
Question 1:
To solve for the number of milliliters of the KOH solution needed, we need to use the pH of the solution. Since the pH is given, we can use it to find the concentration of OH- ions in the solution, which will allow us to calculate the amount of KOH needed.
To do this, we need to use the equation: pH = -log[OH-]. Rearranging the equation, we get: [OH-] = 10^(-pH).
Now, we know that the volume of the final solution is given as 27.0 mL. We can calculate the moles of OH- ions needed using the molarity formula: moles = concentration (M) × volume (L). Since the concentration of OH- ions is the same as the concentration of KOH, which is given as 15.0% by mass, we can convert it to moles using the molar mass of KOH.
Here's the step-by-step solution for Question 1:
1. Calculate the concentration of OH- ions using the given pH: [OH-] = 10^(-pH).
2. Convert the concentration of KOH to moles using the molar mass of KOH. (This can be calculated by adding the atomic masses of potassium (K), oxygen (O), and hydrogen (H)).
3. Use the molarity formula to calculate the moles of KOH needed: moles = concentration (M) × volume (L). Since the volume is given as 27.0 mL, convert it to liters by dividing by 1000.
4. Finally, calculate the volume of the KOH solution needed in milliliters by converting back from moles to volume using the molarity: volume (mL) = moles / concentration (M) × 1000.