2015年1月7日 · In short, Dalton suggested $\ce{^1H}$ as the basis of the mass scale, but Ostwald pushed later for $\ce{^16O}$. Unfortunately, no one knew about isotopes yet. The problem was that physics stuck to isotopically pure O-16 for their mass scale, and chemistry used "oxygen" (i.e., with some O-17 and O-18 present).

2017年5月4日 · I thought that only way a nucleus can be NMR active is when the atom has an odd mass, which means that there is an odd number of protons or neutrons and an even number of the other particle.

2020年4月30日 · Thus $\ce{^4He}$, $\ce{^12C}$, and $\ce{^16O}$ are all expected to be spin 0. On the other hand, an isotope with an odd number of protons will have an unpaired proton; and an odd number of neutrons gives rise to an unpaired neutron.

2019年12月3日 · Estimate the bond length of 12C16O (pure rotational spectrum) given J''=3 (15.356 cm-1) and J'=9 (38.356) I understand that the first step is the calculate the rotational constant.

However, physicists used the atomic mass of the nuclide $\ce{^16O}$ whereas chemists used the average atomic mass of natural oxygen. This unit became obsolete when IUPAP (1960), IUPAC (1961), ISO, CIPM (1967) and CGPM (1971) agreed to assign the value 12 to the relative atomic mass of the nuclide $\ce{^12C}$.

2020年4月7日 · Also, 12C = 12 implied acceptable relative changes in the atomic weight scale, i.e., 42 parts-per-million (ppm) compared to 275 ppm for the 16O = 16 scale (which would not acceptable to chemists). Enthusiastically, Mattauch made a worldwide effort in the late 1950s to publicize the 12C = 12 scale and obtain the physicist's approval, while ...

2023年2月24日 · By collisions of fast neutrons with hydrogen atoms in the coolant $\ce{H2O}$ (i.e. the desired moderator effect), recoil protons are produced which can react with $\ce{^16O}$ to form $\ce{^13N}$ or with $\ce{^18O}$ to form $\ce{^18F}$.

2021年10月6日 · Combustion analysis of a hydrocarbon produced 33.01 g CO2 and 4.84 g H2O. I was asked to find the empirical formula of the hydrocarbon. I used these molar mass values for my calculations: C - 12.01...

2017年5月13日 · Since only ordinary water, i.e., $\ce{H2^16O}$, is of interest in the OP's question, the aquamolality is the same as the molality, so the solution is simply 0.5 molal. The measurements were reported to have been made at room temperature, with no specific temperature given. Hence, the solution molarity is approximately 0.5 M. Reference

2024年8月31日 · 1) 6.02 x 10 (23) amu is same as 6.02 x 10 (23) atoms? 1 mole is 6.02 x 10 (23). It can be atoms or molecules or particles regardless of atoms gram like 12 bananas is dozen regardless 12 bananas we...