The Stack Overflow podcast is back! Listen to an interview with our new CEO.

Questions tagged [physical-chemistry]

The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

3,057 questions
Filter by
Sorted by
Tagged with
3k views

Do catalysts undergo physical changes during a reaction?

I know that catalysts don't undergo chemical changes during a reaction, but do they undergo physical changes? If they do, are there any examples?
2k views

226 views

For a given teabag and dunking duration - will I get more caffeine in a bigger cup or the same amount?

When choosing a cup of tea, I can choose a big cup or a small cup. I'm wondering if I get more caffeine with the bigger cup or the same amount of caffeine. (in moles) My question is: For a given ...
709 views

Finding the final temperature

If $125$ Calories of heat is applied to $60.0\text{g}$ piece of copper at $21.0^\circ\text{C}$, what will the final temperature be? The specific head of copper is $0.0920 \text{ cal/gC}$. All I have ...
6k views

Why do solutions become saturated?

Why can a solvent dissolve only a particular amount of solute? If we add more solute to the solution, the number of solute particles in contact with water increases. So rate of dissolution should ...
4k views

Equilibrium calculation gives negative molarity

There is a reaction: $$\ce {ClF3 <=> ClF + F2}$$ with $\ce {K_\mathrm{c} = 2.48 x 10^{-3}}$ Initially, $\ce {[ClF3] = 0.25 M}$, $\ce {[ClF] = 0.031 M}$, and $\ce {[F2] = 0.02 M}$. $\ce {F2}$ ...
52 views

Z:#Neutrons Ratio

Is there a fixed ratio that can be used to calculate the number of neutrons in the nucleus of the most stable isotope of an element by knowing the atomic number? Side question: if Z is the symbol for ...
232 views

Why is the maximum % for a gold alloy 92%?

The assignment question is asking us to explain why you can't get more than 92% gold in a gold alloy, and I can't seem to find out why it's specifically 92% in either the textbook or online. Any ...
6k views

How does molecular structure affect physical properties?

The question sounds vague and non-specific because my background in chemistry is limited to undergrad college courses. However, I am interested in learning the correlations between the atom-by-atom ...
5k views

Does rate of Evaporation change with surface area?

Two vessels of the same volume, in the same location and open to the atmosphere. One is of a small diameter, the other is of a larger diameter. The question is will the vessel with the larger surface ...
1k views

Solubility, pressure and Henry's law

Determine the solubility of $\ce{N2}$ in water exposed to air at $\pu{25^\circ C}$, if the atmospheric pressure is $\pu{1.2 atm}$, assume that the mole fraction of nitrogen is $0.78$ in air and the ...
376 views

What does the negative superscript in the term symbol for ground state Oxygen stand for?

I think that I understand most of the parts of the symbol shown for ground state oxygen $\ce{{}^{16}O2}$, which is ${}^{3}\Sigma^{-}_{g}$. However, I was hoping that someone could tell me what ...
174 views

Nature of transition metals [duplicate]

The transition metals have valence and penultimate shell incompletely filled . so does this mean that the transition metals first fill up their valence shell and then penultimate shell?
9k views

The last element's atomic number

I was just thinking what can be the last atomic number that can exist within the range of permissible radioactivity limit and considering all other factors in quantum physics and chemical factors.
64k views

What is the differences between partial pressure and vapour pressure?

Was looking at Henry's law and Raoult's law constants and there seemto be lots of equations involved. Henry's law involves partial pressure and the latter involves the vapor pressure. Wondering what ...
404 views

To which state of matter does the flame belong to?

I had this question from the day (9 years old, now 16) that I learned about states of matter. I have asked many of my teachers, some of them told me it's a gas some that it's a plasma. Can anyone ...
62 views

What is the nature and character of fire? [duplicate]

What is fire? Is it a material or energy or something else? Please explain it to me. My friend asked me this. I am stuck with this problem.
122 views

Why is the pressure value altered in this gas law numerical?

When I work through the following problem it is unclear to me why 0.00120 mmHg is converted to 0.00332 mmHg. What is the temperature of 0.00332 g of mercury in the gas phase with pressure of 0....
3k views

How do I determine crystal field splitting (for example, for [Ni(CO)4])?

How to know how many electrons are there in $T_{2g}$ and $E_g$ orbitals? I think rather than a broad answer, an example would help. So, consider the compound $\ce{Ni(CO)4}$ and how to calculate CFSE ...
112k views

What is the pKa Range for weak acids and bases?

Am I correct in assuming that the following is true? $\mathrm pK_\mathrm a < 3$ is for a strong acid $3 < \mathrm pK_\mathrm a < 7$ is for a weak acid $7 < \mathrm pK_\mathrm a < 11$ ...
227 views

What can I use as a sacrificial electrode to stop the oxidation of aluminium?

For a solution of chromimum phosphate when putting in to solution aluminum there is removal of the aluminum. It is possible to prevent a galvanic cell, stop the etching of the aluminum, by putting ...
1k views

Alternatives to Ring Stands

I'm trying to find an alternative to simple ring stands to hold a simple electrochemical cell. The issue is that it is difficult to adjust the height to the right position to within even a couple ...
147 views

Do the compounds NaₓIrO₂ and NaOsO₂ exist?

Based on some physics background, I want to know whether have scientists synthesized these two materials: $\ce{Na_{$x$}IrO2}$ and $\ce{NaOsO2}$ in the lab, if so, what properties do they have? I ...
201 views

Ideal gas derivations

For an ideal gas, how can someone obtain this: $$\bar{V}dP = RdT- P \bar{dV}$$ from which it can de deducted, that for a constant temperature $$\frac{dP}{\bar{dV}} = -RT$$
1k views

What type of sensor technologies exist to determine the chemical composition of a polymer?

Let's say I have several pieces of trash and each is made with a different type of material like: Plastic bottle : High Density Polyethylene (HDPE) Cereal box : Paperboard & Epichlorohydrin ...
24k views

Why does ZnO turn yellow when it is hot?

Why does ZnO's color become yellow when it is hot? I have read that it is because of physical properties, but I need a more elaborate explanation.
12k views

How do I distinguish between internal energy and enthalpy?

I am finding it hard to distinguish between the two. Can someone explain the two terms and the difference between them? I tried learning from Wikipedia, but it said for both the above terms that it ...
44k views

Why is the enthalpy change not zero in an adiabatic process?

Which of the following must be true for adiabatic processes? $C_V = C_p$ $\Delta H = 0$ $\Delta U = 0$ $\Delta S = 0$ $q = 0$ (Source: Chemistry GRE) The answer is $q = 0$. From ...
175 views

Could micrograms of polonium really change the viscosity of a whole teapot?

I was reading How radioactive poison became the assassin’s weapon of choice and it opens describing how The men eventually left, and Andrade cleared the table. As he poured the remaining tea away, ...
4k views

What makes substances explosive

Can someone explain clearly to me why some things are explosive?
23k views

Why do bubbles form when it rains?

I noticed sometime ago that bubbles formed in puddles/streets whenever it rained. I am wondering if someone could tell me what could cause such bubbles. I examined the bubbles again today more closely ...
2k views

Can an aqueous solution conduct electricity forever?

We know that pure water does not conduct electricity, but salt water is a decent conductor. This is commonly explained by saying that “the ions carry the current through the solution”, which is an ...