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Questions tagged [ph]

pH (or the potential of hydrogen) is a scale used to measure how acidic or basic an aqueous solution is.

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1answer
69 views

Why is the pH level of carbonation loss decreasing then increases afterwards?

We have done an experiment of the titration of unsealed sprite soda to find the amount of carbonic acid being loss on various duration (0 to 1 hour), due to decrease pressure. The calculation was to ...
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Do TDS meters measure HCO₃⁻/CO₃²⁻?

I am trying to add $\pu{2 g}$ of $\ce{KHCO3}$ to $\pu{20 L}$ of RO water $(\mathrm{pH} = 5.2)$ which theoretically it will add $$ \begin{array}{lr} \hline \ce{K+} &\pu{10.32 ppm} \\ \ce{HCO3-} &...
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Is it possible to raise pH in RO water without Na, Mg, K, Ca, S addition?

Maybe the question in the title is simple (=stupid) and the answer is 'simple No' but I have the urge to ask. Some background, I have an aquarium which I use RO water and I use some portions of $\ce{...
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2answers
281 views

pH of strong acid weak acid mixture [closed]

Question: $\ce{H2S}$ ($\pu{0.1M}$; $K_\mathrm{a} = 1.2×10^{-20} $) and $\ce{HCl}$ ($\pu{0.3M}$) with same volume are mixed together. What is the resultant $\mathrm{pH}$? My approach: Let the volume ...
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1answer
49 views

Calculating molecular weight of an acid based on given values of mass, volume, pH and pKa

This is what I thought was an easy problem but according to a given answer I am doing it wrong: $\pu{11 mg}$ of a monoprotic acid was dissolved in $\pu{0.5 l}$ of water. The resulting $\mathrm{pH}$ ...
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1answer
153 views

Why do weak acids like ethanol not act as a strong base in water?

In water, ethanol has a $\mathrm{p}K_\mathrm{a} = 15.9$ which means that its $\mathrm{p}K_\mathrm{b}$ is $-1.9$. Which implies that all weak acids in water are in fact strong bases. But this is not ...
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1answer
103 views

Calculating the ph of an unknown solution by measuring the precipitate [closed]

You have an unknown metal hydroxide, but no meters or indicators. You have lead (II) nitrate, which is soluble in it, and lead (II) hydroxide that is insoluble in it. You take one liter of the unknown ...
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51 views

Calculating pH of solution

What is the $\mathrm{pH}$ when you dissolve equal amounts of $\ce{NaHCO3}$ and $\ce{Na2CO3}$ in water? When both of the compounds are dissolved, we will have equal amounts of $\ce{HCO3-}$ and $\ce{...
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1answer
40 views

Calculating pH of weak base and strong acid: Why is K(a) not required?

Question: 35mL of 1.5M $\ce{HCN}$, a weak acid(K(a)= $6.2*10^{-10}$) is mixed with 25mL of 2.5M $\ce{KOH}$. Calculate the pH of final solution. The solution given in my textbook is as follows:- $\ce{...
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1answer
37 views

Could this solution be resolved by titration?

I have a mixture of $\ce{NH_4NO_3}$ and $\ce{NH_3}$ at $\ce{pH}$ of about 13. It is possible to determine the concentration of both on them by acid-base titration? I was told it's possible, and that ...
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1answer
39 views

When there is an increase in temperature, how is the pH of the ocean affected? (Question is related to ocean acidification)

This is my current understanding: Ocean acidification is the result of atmospheric $\ce{CO2}$ dissolving in the ocean's water. When this occurs the $\mathrm{pH}$ of the ocean decreases (from the ...
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1answer
96 views

pKa value of an indicator

Can we deduce the actual value of $\mathrm{p}K_\mathrm{a}$ of an indicator if the $\mathrm{pH}$ range has been given? I know that $\mathrm{pH}$ range is physically the range of values over which an ...
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2answers
80 views

Citric acid and ammonium nitrate

Soil based question. I have soil with to much Ammonium Nitrate in it. I am wondering if I use citric acid and water mixed will that flush out the extra Ammonium Nitrate that has built up in the soil. ...
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2answers
123 views

Can I use the Henderson–Hasselbalch for calculating the pH of non-buffer systems?

Can I use the Henderson–Hasselbalch equation on reactions that are not buffers? When I read up on the derivation of the equation, I noticed that there is absolutely no assumption on the relative ...
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30 views

Impact of pH? Change in Binding Affinity of protein-ligand complex based on pH and Kd?

When the $\mathrm{pH}$ was $5.0$, the temperature was $\pu{25 °C}$,the $K_\mathrm{D}$ was $\pu{5 μM}$, and [L] was equal to $K_D$, the protein(s) were half bound. Question considers half bound ...
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1answer
63 views

pH After Titration

50mL $\ce{SO2}$ titrated with 0.1M of $\ce{KBrO4}$ with reaction: $$\ce{KBrO4 + 4SO2 + H2O -> 4H2SO4 + KBr}$$ The equivalent point is reached when the volume of $\ce{KBrO4}$ is used as much 50mL. ...
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1answer
311 views

How accurately does (pKa1 + pKa2) / 2 estimate the pH of an amphoteric salt?

This question came up when answering Find the pH and amphiprotic salt is added to water at room temperature. If we dissolve $\ce{NaHA}$ in water, the species $\ce{HA-}$ can act as acid or base: $$ \...
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3answers
632 views

Can solid acids and bases have pH values? If not, how are they classified as acids or bases?

This answer states $\mathrm{pH}$ is the aqueous concentration of $\ce{H3O+}$ or $\ce{H+}$ ions in soution. I would not say that ice lacks $\ce{H3O+}$ and $\ce{OH-}$ ions as ice's structure would ...
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1answer
137 views

At what acid concentration does potassium metabisulfite react?

I'm in the process of developing a well preserved food-stuff containing potassium metabisulfite and a number of acids (acetic, ascorbic, malic, tartaric, citric, lactic). Wine-making literature ...
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1answer
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pH of CH3COOH + HCl solution (shouldn't be a buffer)

$\pu{0.05 L}$ of a solution containing $\pu{0.3 M}$ acetic acid $(\ce{CH3COOH}$, $K_\mathrm{a} = \pu{1.8e-5})$ are added to $\pu{75 mL}$ of a solution containing $\pu{0.02 M}$ hydrochloric acid ($\ce{...
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1answer
365 views

pH of a Calcium Hydroxide vs Magnesium Hydroxide solution [closed]

In an AQA 2017 Chemistry paper, a $0.0131 \pu{mol}\cdot\pu{dm^-3}$ saturated solution of calcium hydroxide is prepared and then the question asks to predict the pH of a similar solution of magnesium ...
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6answers
251 views

How to calculate pH of basic salt solution mixed with strong base?

Calculate $\mathrm{ pH }$ of $\pu{ 0.05 mol }$ of $\ce{Zn(CH3COO)2}$ and $\pu{ 0.025 mol }$ of $\ce{ NaOH }$ dissolved in $\pu{ 1 L }$ of distilled water? I tried to use the systematic method by ...
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1answer
110 views

How do I calculate the hydronium ion concentration if I know the strontium hydroxide concentration?

This is my first question so I would appreciate feedback on how to ask better questions. Forgive me if I don't know how to properly format math/chem. The guide is confusing. I was taking a practice ...
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2answers
52 views

Calcium Phosphate Dissolution

For what reason does Calcium Phosphate dissolute at low pH? What makes it pH dependent? This question arised after reading about the calcium phosphate bridges in casein micelles and how they 'break ...
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1answer
107 views

By how many pH units does rain vs distilled water change a soil pH test?

Sources state that the concentration of $\ce{H2CO3}$ in rain is of a few µmol; I don't know if that's per ml. The buffering effect of most soils is >1000 µmol $\ce{H+}$/kg. Is the difference from low ...
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34 views

Preparation of Copper (II) Sulfate Pentahydrate Solution

how would you make a solution of Copper (II) Sulfate Pentahydrate to achieve 150, 200, 250 and 300 mgL−1 concentration of copper? I do not have the anhydrous version of the solute. Also, when I ...
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2answers
26 views

Influence of pH on precipitate crystallite sizes?

It's normally assumed that a higher pH of solution would slow nucleation rates and hence lead to larger crystal formation. I've found literature that it is due to solid-liquid inter-facial tension. ...
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Naming convention for buffer solutions/systems

Is there an official naming convention to follow for buffer solutions/systems? I've noticed that the name of the buffer usually just follows the name of the salt (ex. sodium acetate buffer), but what ...
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1answer
45 views

Reference Books on Electrolysis and Chemical Titration process [closed]

I'm in a General Chemistry course in college. We have laboratory, and then we are supposed to make a report on what we did, etc. I'm not entirely sure what the last laboratory was about, but it was ...
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1answer
797 views

Calculate pH at equivalence point [closed]

Calculate the pH at the equivalence point of a titration of 62 mL of 0.1 M $\ce{CH_3NH_2}$ with 0.20 M HCl. The $\ce{K_b}=4.4\cdot10^{-4}$. At the equivalence point, the moles of CH3NH2 equals the ...
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1answer
70 views

Getting pH of a weak acid and conjugate base with a given ratio [closed]

A practice question reads What is the $\ce{pH}$ of a solution of a weak acid and its conjugate base when the ratio of the concentrations of the conjugate base/weak acid is 1/3? (the weak acid $K_\...
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1answer
75 views

Can buffer solutions be used to control the pH of ethanol?

For my experiment, I want to investigate the effect of differing pH on the solubilities of a sparingly soluble drug. However, the solubility is too low for me to conduct a reliable study on the ...
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1answer
54 views

Adding weak acid to strong base, find pH [closed]

30mL 3M acetic acid (pka 4.7) is added to 50mL 2M NaOH. what is the resulting pH a) <2 b) between 2 and 7 c) 7 d) >7 ans =d can someone explain how to actually solve for pH? the solution ...
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1answer
95 views

Using electrolysis of water as a proton generator [closed]

I'm working on a project right now, where the challenge is to try to use electrolysis as a way of controlling the $\ce{pH}$ of water. I've set up an experiment where I have two separate chambers or ...
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26 views

Is it possible to determine the pH that results in maximum buffer capacity from a Bjerrum plot?

If buffer capacity is normally at a maximum when pH=pKa because there is an equal concentration of acid and conjugate base in the buffer (so there's an equal amount of substance that can absorb acid ...
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2answers
145 views

Calculating the pH of a buffer made by a diprotic acid and its double salt

The concentration of the diprotic acid (tartaric acid) will be constant at $\pu{ 0.1 M}$. I want to find the concentration of its double salt (potassium sodium tartrate) needed to create a buffer of $\...
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1answer
82 views

Why does buffer capacity of tartrate buffer generally decrease as the buffer pH increases?

From what I see, the buffer capacity of tartrate buffer is generally decreasing as buffer pH increases. Why is this? Also, does this mean that tartrate buffer doesn't have a maximum buffer capacity at ...
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1answer
125 views

What is the formula for theoretical buffer capacity for a diprotic buffer system?

According to Chembuddy, the formula for theoretical buffer capacity for a monoprotic buffer system is as follows: $$β = 2.303\left(\frac{K_\mathrm{w}}{[\ce{H+}]} + [\ce{H+}] + \frac{C_\mathrm{buf}...
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1answer
163 views

Why is maximum buffer capacity for some diprotic buffers not when pH = pKa?

According to Rajkovic et al. [1]: $$β = \frac{[\ce{H+}]}{K_\mathrm{w}} + 2.303\cdot\frac{[\ce{H+}]\cdot K_\mathrm{a}\cdot c}{[\ce{H+}] + K_\mathrm{a}}$$ where $K_\mathrm{a}$ is the ...
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1answer
231 views

pH of CH3CH2NH2 buffer solution [closed]

For $\pu{550.0 mL}$ of a buffer solution that is $\pu{0.170 M}$ in $\ce{CH3CH2NH2}$ and $\pu{0.150 M}$ in $\ce{CH3CH2NH3Cl}$, calculate the initial pH and the final pH after adding $\pu{0.020 mol}$ ...
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132 views

Dissociation degree hell, Ostwald's law of dilution

Greetings dear chemists! I got a nice exam problem on wich i am stuck for hours, well maybe the problem is with me. I know the problem can be solved. So here we go. We got a weak monoprotic acid, we ...
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143 views

Effects of Ka on the Half-Equivalence Point

I'm new to studying chemistry at a university level and am currently reviewing acid-base titrations. I am wondering about the relationship between your ionization constant for a weak acid ($K_\mathrm{...
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Why are synthetic pH indicators used over natural indicators?

Synthetic indicators seem to be exclusively used when determining the pH of a substance with an indicator (with the exception of that school experiment where you boil cabbage to demonstrate natural pH ...
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1answer
64 views

Drug pH and pKa known, is it an acid or a base? [closed]

I want to answer the question if a drug which is analysed for pH and pKa is ionised or not ionised in a cow stomach with a pH of 6. The drug has a pH of 8,52 and a pKa of 8,78. Since the pH is 8,52 ...
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1answer
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The pH scale/calculating pH level [closed]

How much water do you need to add to 10 mL of a solution of HCl with a pH of 4 to change the pH to 5?
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1answer
42 views

Identifying Lewis acid

What is the Lewis acid on the reactants side? $$\ce{HNO2(aq) + HPO4^{2-}(aq) <=> NO2-(aq) + H2PO4-(aq)}$$ The book says it is the $\ce{H+}$ only, not the whole molecule of the nitrous acid, ...
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2answers
191 views

not understanding buffering region vs equivalence point [closed]

"During the titration of a weak polyprotic acid with a strong base, the first stoichiometric equivalence point occurs when the moles of added base are equal to the moles of the initial acid species. ...
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1answer
156 views

Determining the reduction potential of a half cell reaction at a given pH

$E^\circ_\ce{Cu^2+|Cu} = \pu{0.34 V}$. What will be reduction potential at $\mathrm{pH} = 14$ for the same couple? Given that $K_\mathrm{sp}$ of $\ce{Cu(OH)2}$ is $10^{-19}$. My Attempt I think ...
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1answer
143 views

Determination of pKb of a mono acidic base

$20$ mL of a weak monoacidic base($\text{BOH}$) requires $12$ mL of $0.3$ M $\text{HCl}$ solution for the equivalence point. During titration, the pH of the base solution was $10$ upon the addition of ...
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1answer
257 views

Calculate pH of a buffer solution

Calculate the pH in a buffer prepared from $\pu{50 mL, 0.30 M}$ formic acid ($\ce{HCOOH}$) and $\pu{30 mL, 0.40 M}$ sodium formate ($\ce{HCOONa}$). My way of solving: $n_{\ce{HCOOH}} = 0.05 \times ...