User ACR - Chemistry Stack Exchange

49 votes

Which "exotic salt" can lower water's freezing point by 70 °C?

answered May 5, 2019 at 3:25

30 votes

Accepted

Is "Sulfuric acid... makes a poor electrolyte... very little of it will dissociate into ions" really true? What does that actually mean?

answered Jun 17, 2021 at 5:56

27 votes

Why does hydrogen burn with a pale blue flame while its emission spectral lines are red in colour?

answered Apr 11, 2021 at 16:26

26 votes

Why is solubility often listed as a chemical property? Isn't the action of dissolving just a physical change?

answered Apr 9, 2020 at 19:39

23 votes

Commercial chalk for kids composition

answered Apr 27, 2020 at 23:23

22 votes

What is the difference between "vapour" and "gas"?

answered Apr 19, 2021 at 16:38

22 votes

Accepted

Why does the graph of the electrical conductivity of sulfuric acid/water solutions have this knee in the ~85%-~92% range?

answered Jun 19, 2021 at 1:32

22 votes

Accepted

True or false: "A used AA battery contains fewer moles of electrons than a new AA battery."

answered Nov 26, 2021 at 0:15

19 votes

What would be the effect of adding liquid beyond the calibration mark on a volumetric flask?

answered Aug 30, 2020 at 13:44

19 votes

Accepted

What is the intuition behind 'mol' as a unit 'symbol'

answered Oct 12, 2020 at 17:11

19 votes

What is the mathematical meaning of the plus sign (+) in chemical reaction equations?

answered Mar 11, 2021 at 15:36

19 votes

Is an acid a salt or not?

answered Jul 11, 2019 at 14:35

18 votes

Accepted

How is hair tissue mineral analysis performed?

answered Jun 19, 2019 at 1:14

18 votes

Accepted

When I burn isopropyl alcohol (IPA), it burns orange. But when I burn ethyl alcohol, it burns totally blue. Why is this?

answered Mar 23, 2020 at 23:04

18 votes

Benzene to phenol in a single step

answered May 21, 2020 at 5:36

17 votes

Accepted

Why does almost every drug that causes dependence have this "-ine" suffix?

answered Dec 24, 2021 at 18:42

17 votes

Accepted

Difference between a "cartoon" flame test and a "real" flame test? How do chemists do flame tests correctly?

answered Oct 12, 2022 at 1:19

16 votes

Accepted

How would you know if the light emitted is of one wavelength or if it is a mixture of two or more wavelengths?

answered Jun 25, 2020 at 0:41

16 votes

How did Mendeleev know elements from compounds or mixtures?

answered Jul 28, 2020 at 19:21

16 votes

Accepted

Is it possible to measure pH without physically coming into contact with a solution?

answered Apr 11, 2020 at 15:29

16 votes

Why is black-body radiation curve smooth without a sharp cutoff?

answered Aug 13, 2020 at 5:28

16 votes

Accepted

Why is it considered acid rain with pH <5.6?

answered Jul 27, 2019 at 19:06

16 votes

Accepted

Why does concentration of solutions of alkali metals in liquid ammonia change the magnetic properties?

answered Sep 26, 2019 at 14:09

15 votes

Accepted

What is "super" in superphosphate?

answered Aug 19, 2019 at 0:28

15 votes

Is it possible to achieve a level of "truly zero" concentration?

answered Aug 7, 2020 at 22:27

15 votes

Accepted

Why isn't sodium hydrogen phthalate used instead of KHP?

answered Oct 2, 2020 at 1:00

15 votes

Why is H2N2O2, and not HNO, called hyponitrous acid?

answered Aug 20, 2022 at 23:45

14 votes

Accepted

Why does the same electron transition release photons of different frequencies for some elements?

answered Oct 11, 2022 at 3:22

14 votes

Accepted

What is the standard industrial method for measuring caffeine content in food and drinks?

answered Nov 18, 2022 at 3:00

14 votes

Accepted

Why are some colorings called "Fast", i.e. Fast Yellow AB (E105)?

answered Oct 26, 2021 at 21:01

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886 Answers

Which "exotic salt" can lower water's freezing point by 70 °C?

Is "Sulfuric acid... makes a poor electrolyte... very little of it will dissociate into ions" really true? What does that actually mean?

Why does hydrogen burn with a pale blue flame while its emission spectral lines are red in colour?

Why is solubility often listed as a chemical property? Isn't the action of dissolving just a physical change?

Commercial chalk for kids composition

What is the difference between "vapour" and "gas"?

Why does the graph of the electrical conductivity of sulfuric acid/water solutions have this knee in the ~85%-~92% range?

True or false: "A used AA battery contains fewer moles of electrons than a new AA battery."

What would be the effect of adding liquid beyond the calibration mark on a volumetric flask?

What is the intuition behind 'mol' as a unit 'symbol'

What is the mathematical meaning of the plus sign (+) in chemical reaction equations?

Is an acid a salt or not?

How is hair tissue mineral analysis performed?

When I burn isopropyl alcohol (IPA), it burns orange. But when I burn ethyl alcohol, it burns totally blue. Why is this?

Benzene to phenol in a single step

Why does almost every drug that causes dependence have this "-ine" suffix?

Difference between a "cartoon" flame test and a "real" flame test? How do chemists do flame tests correctly?

How would you know if the light emitted is of one wavelength or if it is a mixture of two or more wavelengths?

How did Mendeleev know elements from compounds or mixtures?

Is it possible to measure pH without physically coming into contact with a solution?

Why is black-body radiation curve smooth without a sharp cutoff?

Why is it considered acid rain with pH <5.6?

Why does concentration of solutions of alkali metals in liquid ammonia change the magnetic properties?

What is "super" in superphosphate?

Is it possible to achieve a level of "truly zero" concentration?

Why isn't sodium hydrogen phthalate used instead of KHP?

Why is H2N2O2, and not HNO, called hyponitrous acid?

Why does the same electron transition release photons of different frequencies for some elements?

What is the standard industrial method for measuring caffeine content in food and drinks?

Why are some colorings called "Fast", i.e. Fast Yellow AB (E105)?