# Questions tagged [units]

For questions about the definition and usage of units of measurement.

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### Dimensional Analysis: Conversion of units from m/s^2 to mi/hr^2 [closed]

I was given a dimensional analysis problem that is stated like this: The acceleration due to gravity is $\pu{9.81 m/s2}$. What is the gravitational acceleration expressed in $\pu{mi/hr^2}$? The ...
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### Thermochemistry: On Units of Enthalpy Change and Implicit Given of Initial Temperature of Calorimeter

I would like to ask two separate questions. But first, so that we are on the same page, the experiment used a constant-pressure calorimeter, and it is a neutralization reaction of 1M of HCl and 1M of ...
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### Converting mEq per gram to Degree of Substitution?

I need to order some carboxymethyl cellulose for some cation exchange chromatography experiments. But the stuff we used last time has been discontinued. The discontinued product had a mEq/gram of 0.9 -...
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### Why is the units of rate constant dependent on the order of the reaction?

In many textbooks, it is written that For order (m + n), the rate constant, k has units of mol1−(m+n)·L(m+n)−1·s−1 However, by the Arrhenius equation, k can be expressed as k = PZexp(-Ea/RT) and ...
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### What is a Herzberg?

Whatman lists the flow rates for their filters in a unit called a 'Herzberg': What is this? I've been searching around and I did find information about Herzberg flow rate testers, for example this ...
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### What is the dimension of Avogadro's constant?

What is the dimension of Avogadro's constant ($N_\mathrm{A}$). On Wikipedia it says it is dimensionless, but in Nigel Wheatley's article (pdf) On the dimensionality of the Avogadro constant and the ...
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### What is the unit of Z effective?

Z effective is the net positive charge experienced by an electron. But what is the unit of this net charge: coulomb (C) or microcoulomb (μC), or something else?
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### Are atomic mass unit (amu), unified mass unit (u) and Dalton (Da) the same unit but with different names? [duplicate]

I recently read up on some chemistry and found these units of mass: atomic mass unit (amu) unified atomic mass unit (u) Dalton (Da) Are they all the same unit but just with different names or are ...
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### Heat Transfer Coefficient Problem

The Problem An unusual reference gives the formula below for the heat transfer coefficient of an emulsion. $$H = 0.0061\left(X^{0.6} + 0.038T\right)\cdot V^{0.35}$$ In the formula $T$ is the ...
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### Units of the rate constant for reactions whose order is greater than 1

In many textbooks, it is written that: The value of rate constant depends on the nature of the reactants, temperature and catalyst. It is independent of the concentration of the reactants. However,...
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### Why the term 'unified' in “unified mass unit”? [closed]

Why different unit symbols - amu, u and dalton are used for representing atomic mass? And what does the term 'unified' mean in "unified mass unit"? Thank you.
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### Why is the equilibrium constant unitless?

I read that the equilibrium constant is unitless because the molar activities of each of the species are used in the equilibrium expression, not the actual concentrations themselves. I understand that....
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### Standard litres to kg conversion for Hydrogen [closed]

When looking at hydrogen fuel tanks, they often give the capacity in terms of "standard litres". However, I can't find a definition of what this is. I assumed this may mean a litre of hydrogen gas ...
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### Unit analysis for neutralization reaction

What volume of $\pu{0.500 mol L-1}$ $\ce{HCl}$ (in $\pu{mL}$) is required to neutralize $\pu{2.02 g}$ of solid $\ce{NaOH}$ pellets? So far I have tried regular unit analysis: 2.02 g NaOH * 1mol ...
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### Types of concentration units

I would like to ask about a concentration unit. What does it exactly mean when stock concentration of something is, for example, 5X? Thank you in advance!