In chemistry, pH (, denoting 'potential of hydrogen' or 'power of hydrogen') is a scale used to specify the acidity or basicity of an aqueous solution. Acidic solutions (solutions with higher concentrations of H+ ions) are measured to have lower pH values than basic or alkaline solutions.
The pH scale is logarithmic and inversely indicates the concentration of hydrogen ions in the solution. This is because the formula used to calculate pH approximates the negative of the base 10 logarithm of the molar concentration of hydrogen ions in the solution. More precisely, pH is the negative of the base 10 logarithm of the activity of the H+ ion.At 25 °C, solutions with a pH less than 7 are acidic, and solutions with a pH greater than 7 are basic. Solutions with a pH of 7 at this temperature are neutral (e.g. pure water). The neutral value of the pH depends on the temperature – being lower than 7 if the temperature increases. The pH value can be less than 0 for very strong acids, or greater than 14 for very strong bases.The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. Primary pH standard values are determined using a concentration cell with transference, by measuring the potential difference between a hydrogen electrode and a standard electrode such as the silver chloride electrode. The pH of aqueous solutions can be measured with a glass electrode and a pH meter, or a color-changing indicator. Measurements of pH are important in chemistry, agronomy, medicine, water treatment, and many other applications.
Homework Statement
Determine the pH of0.15 M solution of sodium acetate, ka = 1.8 x 10^-5
The Attempt at a Solution
Since there are no hydrogen ions that dissolve from sodium acetate, would I use the pH of water =7.0? Is the pH of water even affected by sodium acetate?
for example, ethanoic acid in water,
"="means equilibrium arrows
CH3COOH(aq) + H2O(l) = CH3COO-(aq) + H3O(aq)
we take the pH as the -log of the concentration of H3O ions.
BUT why do we not take in account the effect of the ethanoate ion with water which produces OH-?
CH3COO-(aq) +...
Hello, thanks for reading.
I am solving a lab problem that involves calculating a theoretical pH value, then testing the experimental pH in a lab with tap water that is not the expected pH 7, and comparing the values.
I am determining the theoretical pH value of a 0.1M concentration of...
The problem is:
Calculate the pH of a solution created by mixing 200.0 mL of .400 M acetic acid and 200.0 mL of 1.00 M sodium acetate.
I got 2.02 for the pH, but according to other people in my class that's the wrong answer. Could someone explain how to do this? I used the Initial, Change...
I started this thread a while ago but never figured it out in the end can someone tell me if my idea of this is correct or not.
Lets say I add 2 moles of a weak acid acetic acid to a liter of water (at STP). If I'm not mistaken the acetic acid will dissociate slightly depending on its...
Homework Statement
I need to know how to do the following. If I have 1L of water with a pH of 7 and I add 1mL Vinegar with a pH of 2.4, what will the pH of the solution then be?
I now need to get the pH of the solution back to 7 by adding ammonia which has a pH of 11.6. How much of that do I...
Heres a question involving what I'm talking about
When 5mls of 0.05M CH3COOH is allowed to react with 1.5mls of 0.05M KOH. The pH is found to be 4.43. Using the Henderson-Hasselback equation calculate the pKa.
My teacher told me that you can find the amount of dissociated ions of the...
Homework Statement
The problem is as follows:
100.0 ml of 0.100 M acetic acid is placed in a flask and is titrated with 0.100 M sodium hydroxide . An appropriate indicator is used. Ka for acetic acid is 1.7 x 10 -5. Calculate the pH in the flask at the following points in the titration.
a...
Homework Statement
100.0 ml of 0.100 M acetic acid is placed in a flask and is titrated with 0.100 M sodium hydroxide . An appropriate
indicator is used. Ka for acetic acid is 1.7 x 10 -5Calculate the pH in the flask at the following points in the titration.
a. when no NaOH has been added...
Homework Statement
If one mixed 100mL of .1M Sodium acetate with 100 mL of .1M acetic acid, the pH of the solution would be 4.7 If 60 mL of .1M NaOH were added to this solution, what would be it's pH?
Homework Equations
Henderson Hasselback
pH=pKa+ log(base/acid)
The Attempt at a...
1. COnsider the titration of 80.0 mL of 0.100 M Sr(OH)2 by 0.400 M HCl. Calculate the pH of the resulting solution after the following volumes of HCl have been added.
a. 0.0 mL
b. 20 mL
c.80 mL
Homework Equations
Henderson–Hasselbalch equation or direct -log
The Attempt at a Solution
a) before...
I have no idea how to find the pH of a buffer solution:
Please step by step!
Calculate the pH after 0.020 mol NaOH is added to 1.00 L of:
a mixture containing 0.100 M HONH2 and 0.100 M HONH3Cl
please step by step instruction so I can follow and do other problems on my own! Thanks
Hello!
I was wondering, with questions such as "What is the pH of 0.05 mol dm-3 of HCl?", you specify the pH by simply using the concentration, as it completely dissociates. However, I assume that at such a concentration like this it is not 'pure', and would be present in water. Shouldn't I...
i was recently reading about uv absorbance, and i understand why species such as the phenoxide ion and aniline absorb uv radiation at longer radiation and with more efficiency than their protonated counterparts.
i have spent long hours, however, trying to figure out why a benzoate ion might...
Can anyone tell me what a 1% (mass or volume) sulfuric acid solution is in moles? I want to find out the pH of a 1% (mass or volume) sulfuric acid solution?
I have not searched enough/researched, but my immediate need is to clarify the following in the context of pH electrodes, metallic electrodes and conductivity cells, particularly as regards the way they are conceived/ designed, [WARNING] my queries may be naive [WARNING]:
(1a) Often a vendor...
A .05 M sample of K2HPO4 was dissolved in 800 mL of water, and the pH was adjusted to 7 by using a 1 M solution of H3PO4 followed by water bringing the volume up to 1 L. How many mL of H3PO4 were added? (On this problem charge and mass balance have to be used.)
My problem is just in the...
This is my question:
When a 17.9 mL sample of a 0.493 M aqueous nitrous acid solution is titrated with a 0.476 M aqueous barium hydroxide solution, what is the pH after 13.9 mL of barium hydroxide have been added?
I'm not really sure how to start it?
I have the moles of the acids and the...
Homework Statement
Calculate the pH of 20.00 mL of 0.20 M KHP.
Given: pKa1(H2P)= 2.950 pKa2(H2P)= 5.408
Homework Equations
k = [H][P]/[HP]
The Attempt at a Solution
I used this equation and got:
3.91e-6 = [x][x]/[.2]
x^2 = 7.82e-7
x = 8.8e-4 = [H]
pH = 3.05...
Homework Statement
Calculate the pH of rainwater in equilibrium with SO2 in a polluted air mass for which
the sulfur dioxide concentration is 1ppm.
SO2(g) +H2O(g) = H2SO3(aq) Kh=1M/atm
H2SO3 = HSO3- + H+ Ka=1.7x10-2MHomework Equations
The Attempt at a Solution
I'm pretty lost for this one.
I...
I did an experiment today, I put some magnesium in HCl solution (pH of around 1 or so) , but for some reason the pH decreased (turned more acidic), and my teacher said that's expected but didn't tell me why it happens.
Enlighten me, please.
Homework Statement
What is [H+] and pH for a 100 mM solution of KOH
The Attempt at a Solution
This seems very simple..its only 2 marks but I don't know what I'm doing wrong.
I understand KOH will dissociate into K+ and OH-
pOH=-log(OH) ?
ph + pOH = 14
p[OH]=-log[100x10^-6?]...
Homework Statement
If a solution of a weak acid contains more HA than A-, then
Homework Equations
-
The Attempt at a Solution
the answer is pH > pKa.
Okay my question is why is this the answer. I'm trying to understand in what situation you would have the pH greater or less...
I have been trying to raise the pH of sand filtered salt water. I tried sodium bicarb but have been getting a thick precipitate. I am trying to raise the pH to 9-9.4 It starts out at around 8.2.
I have also tried NaOH and have had no luck maintaining the pH at 9-9.4
Any advice would be much...
The pKa for the dissociation of H3PO4 is 2.15. What is the concentration of H2PO4-1 (in M) at pH 3.21 if the original concentration of the phosphate was 2.37 M?
My Attempt:
Key Information:
pH final: 3.21
Initial Molarity of phosphate: 2.37 M
pKa: 2.15
I started with the first...
1. State the Problem
A water initially contains 40 mg/L of Mg2+. The pH of the water is increased until the concentration of hydroxide ions (OH-) is 0.001000 M. What is the concentration of magnesium ion in this water at this pH? Give you answer in milligrams per liter. Assume that the...
Homework Statement
A solution of histidine has all acid-base groups protonated. The pKa of the carboxy group is 1.8, the amino group is 9.2, and the side chain is 6.0. For each mole of amino acid, 2.5 moles of NaOH are added. What is the pH of the solution?
Homework Equations...
Does anyone know if a Na2CO3 solution will change in pH when you leave it for a month? Will the pH go up or down? I thought maybe the CO2 would escape which would make the pH go higher?
[Solved] pH of Aqueous Solution
Homework Statement
Calculate the pH of the following aqueous solution prepared by adding 3.0L HBr(g), measured at 27 degrees Celsius, 757 mmHg pressure, to sufficient water to give 0.10L of solution.
Homework Equations
pH = -log[H+]
The Attempt at a...
1. Calculate the PH and the POH of the solution obtained by adding .2g of Solid KOH to 1.5 liters of .002M HCL
Homework Equations
3.I understand this is a mol/ liter question. but I just don't understand how to transfer .2g of koh to ml and to find the concentration. I know PH= - log...
Hi,
well my friend is in the final year graduation and he is working on a project a part of it is trying to detect the pH of a certain compound exist in acidic HCl solution, this compund don't remember its name for recent but it has the amino 'NH2" group this compund is in solution of HCL and...
A solution which is formed by combining 200. mL of 0.15 M HCl with 300. mL of 0.090 M NaOH has a pH of ____
ive worked out concentration of H ion is 0.03 and the concentration of OH ions 0.027. but i don't know what to next?
answer is 2.2 thanks
Homework Statement
calculate the formate ion concentration and pH of a solution that is 0.05m in formic acid (HCOOH;Ka=1.8x10^-4) and 0.10M in HNO3.
hey guys just wondering how the equation goes??
like this?? HCOOH + HNO3>>?
Homework Statement
We add 0.535 g of NaOH to 100.0 mL of water at 25degrees. What is [H3O+] in this solution at 25degrees?
hey guys, I've practiced these types of questions alot, but I've never came across one like this before. i tried writing equations and i got this 2NaOH+2H20>>2Na+2H30...
hey guys, I've just started PH, just wondering if you could show me how to do this question. thanks for any help
What is the pH of a solution made by mixing 800 mL of 0.01 M HNO3 and 700.75 mL of water?
Homework Statement
hey guys, I've got a prob, i kinda know how to do this question but i can't get past the first step. i want to write an equilbrium expression by I am not sure what the chemical reaction is. any help would be good
Homework Equations
A solution of a weak acid, HCOOH...
Homework Statement
In this experiment you will find the ionization constant for ammonia, a weak base.
I have completed the experiment, and have the following:
Initial concentration of NH3: 3.708mol/L
Initial pH of NH3: 10.26
Homework Equations
NH3(aq) + H2O(l) <--> NH4+(aq) +...
Homework Statement
If 50ml of 0.004M H2CrO4 was combined with 50 ml of 0.005M HNO3 what is the pH of the resulting solution?
Homework Equations
Moles H3O=Moles OH ?
Formula for KA
The Attempt at a Solution
So, here's what I have so far.
I made the H2CrO4 represent the acid...
Homework Statement
Calculate the pH after 24 mL of 1.00 M NaOH is added from the burette to a beaker containing 25.0 mL of 1.00 M HCl
Homework Equations
pH = -log [H+]
1*10^-14 = [H+][OH-]
The Attempt at a Solution
combined volume = 49mL
n.unreacted(H+) = 0.025-0.024 = 0.001...
Homework Statement
What will be the final pH of the solution if a drop (approximately equal to 1/20 mL) of 1.0M HCl is added to a 10mL 0.1 M CH3COOH sol'n?
Homework Equations
pH = -log [H+]
The Attempt at a Solution
I first determined the number of moles of H+ from the partial...
Homework Statement
Consider the titration of 20.0mL of a 0.100 M solution of HBrO, a weak acid (Ka=2.5x10-9) with 0.200 M KOH. Calculate the pH of the following volumes of KOH.
a. 0.00mL
b. 5.00mL
c. 10.00mL
d. 30.00mL
Homework Equations
pH=pKa +log [base]/[acid]
The Attempt...
Homework Statement
If 0.1g of Silver Nitrite (AgNO2; ksp = 6 x 10^-4) is added to 100 mL of water, what would the pH and pOH be? Note: The Ka for HNO2 is 7.2 x 10^-4
Homework Equations
The Attempt at a Solution
I really am not sure how to approach this except for the fact that...
I searched up NaOH and saw that it's irritating at 0,05 to 0,5 mol/l. So I guess at a pH of 12,7 you will burn your skin. Is that true?
I'm going to do an experiment with 5% NaOH. I thought it was a very small concentration but actually you could burn quite a bit with this solution after a...
Homework Statement
what is the pH of a 4.5x10-8M solution of nitric oxide?
The Attempt at a Solution
well first off..
NO(aq) + H2O(l) <-------> HNO+(aq) + OH-(aq)
or?......-->HNO2(aq) + H+(aq)
Now I have no idea how much of the nitric oxide is actually going to react with the water. I...
Problem:
The pH of pure water at 37°C is 6.80. Calculate Kw,
pOH, and [OH-] at this temperature.
Work:
pH: 6.8
pOH = 14 -6.8 = 7.2
[OH]: 10-7.2 = 6.3 x 10-8 M
Kw= [H3O] [OH] = 1.5 x 10-7 x 6.3 x 10-8 = 1x10-14
Real answer:
pH:6.8
pOH:6.8
[OH]: 1.6x10-7
Kw: 2.5 x 10-14
What...
ive spent over 2 hours on this question and i am unable to solve it. If anyone could help it would be greatly appreciated.
What is the pH of the solution that results from mixing the following four solutions together?
(1) 150. mL of 0.250 M NaCl
(2) 300. mL of 0.200 M HCl
(3) 100. mL of...
1. Homework Statement
Calculate the pH of a solution made by dissolving 10.6 g caffeine (C8H10N4O2, a weak base, Kb = 4.1 x 10-4) in enough water to make 100. mL of solution.
Homework Equations
pH = -log [H3O+]
kb = kw/ka
The Attempt at a Solution
I first found conc.:
MM=...
Homework Statement
What is the pH of the solution that results from mixing the following four solutions together:
(i) 150 ml of 0.250M NaCl
(ii) 300 ml of 0.200M HCl
(iii) 100 ml of 0.050M HNO3
(iv) 450ml of 0.200M NaOAc
Homework Equations
The Attempt at a Solution
Firstly...