Questions tagged [numerical-analysis]
The numerical-analysis tag has no usage guidance.
28
questions
0
votes
0answers
48 views
Calculating the weight of a chemical within a liquid mixture
I want to know the weight of ethylene glycol in a mixture of Shellzone 50/50 Antifreeze. I have taken the mid-range of 40-60% from the safety data sheet(SDS) for the amount of ethylene glycol in the ...
9
votes
2answers
390 views
How to (numerically) model a phosphoric acid titration curve
I've been learning how to simulate a 1M phosphoric acid titration curve using numerical methods in R.
So far has this has been the best curve:
Notice how it flattens out (artificially) towards the ...
2
votes
1answer
60 views
The algebraic problem in the equilibrium of weak acids and bases
I have had some trouble verifying the systematic treatment in a weak acid base weak balance. The great equation I must arrive at is this:
and I just can't see clearly how to get that equation from ...
2
votes
1answer
97 views
% coefficient of variation (%CV) for log-linear and log-log regression (calibrations)
I have a data set comprising the peak areas of an analyte measured in spiked calibration samples at 'known' and different concentrations levels. For each concentration level I have 5 replicates. My ...
2
votes
4answers
1k views
How to read a chromatography calibration curve?
I am a high school student who has been studying a bit of chromatography. I came across calibration curve during class and I trying to figure how to read it and use it? I have no clue how to read off ...
4
votes
1answer
86 views
Modelling pH as function of time and position
I already posted this on the Engineering Stack Exchange under Chemical Engineering as I don't know where it's a better fit.
I have a system whose initial state consists of three different sections ...
2
votes
0answers
262 views
Data analysis in TCSPC for fluorescene decay (reconvolution with measured IRF)
I am trying to understand the data analysis of fluorescence decay counts measured by TCSPC technique, particularly with reconvolution with measured IRF.
I am able to get the fitted counts (given by ...
1
vote
0answers
37 views
Column Dispersive Mass Balance analytical / numerical solution
Is there any analytical solution for the most common expression of column mass balance:
$\dfrac{\partial C}{\partial t} + \left(\dfrac{1+\varepsilon}{\varepsilon}\right)\dfrac{\partial q} {\partial t} ...
3
votes
1answer
921 views
Calculating the total uncertainty of the final product
I have performed a large number of calculations in order to determine the ethanol content of wine. These included titrations using burettes, mass measurements using analytical balances, and others. I ...
5
votes
4answers
849 views
accurate measurement from inaccurate tools [closed]
It is a very general question. Is there a good way to systematically increase the accuracy and precision of a measuring tool using only mathematical means? For example, average 10 measurements can ...
1
vote
1answer
143 views
Balancing chemical reactions, issues of Gauss's elimination method [duplicate]
I am trying to balance some chemical reactions by using the Gauss' elimination method and I noticed that this method does not work if the creation of a matrix with exactly one degree of freedom is not ...
5
votes
1answer
105 views
Factorizing Slater determinant into product of spin-up and spin-down slater determinant
I am reading the book on MONTE CARLO METHODS IN AB INITIO QUANTUM CHEMISTRY by Hammond and Lester. (Chapter 5-Variational Trial Functions, Section 5.3-Hartree Fock and Beyond, Sub-Section 5.3.3 ...
3
votes
0answers
232 views
Good software/module in python to determine nuclear attraction integral in Slater type orbital basis sets
I am trying to solve a Hamiltonian of one electron and 10 stationary nuclear centers. here, the electron is treated quantum mechanically and nuclear centers are treated classically objects. The ...
2
votes
1answer
115 views
what is the issue in evaluating two electron integral?
What sort of issue is there in two electron integral in quantum chemistry ? Is it a problem of convergence when we do numerically? Can someone suggest any review article or reference articles which ...
-2
votes
1answer
373 views
Chemistry - Solutions
Please give me a few hints as to how I can approach this problem
A mixture of two miscible volatile ideal liquids P and Q (obeying Raoult’s law) is kept in a vessel (molar ratio of P and Q in the ...
3
votes
0answers
44 views
Limit to volume change in a discretized mathematical model?
I have set up a mathematical model describing the diffusion of ozone out of a gas bubble. The bubble is surrounded by a thin gas film. So actually, the model describes the diffusion of ozone through ...
2
votes
1answer
131 views
Current in a Concentration Cell
I would like to know if there is a simple function that gives the current as a function of time in a concentration cell. The current is measured in the wire connecting the two terminals of the cell. ...
3
votes
1answer
184 views
How to numerically solve a reaction network with fast equilibrium steps?
For example If I have to solve the following reaction numerically
\begin{align}
*\ce{ + A(g) &<=>[K1] [A*]} \tag{1}\\
\ce{[A{*}] &<=>[k1][k-1] [B{*}]} \tag{2}\\
\ce{[B*] &&...
0
votes
1answer
5k views
How to round correctly when calculating the average and standard deviation?
Is my Chemistry book wrong on the significant figures in this exercise?
Why did they round to 0.16 instead of 0.1580 ?
Also why did they round down the means?
0
votes
1answer
2k views
Find molar concentration of sodium carbonate dissolved in water
The question is
A solution of $\ce{Na2CO3}$ is made by dissolving $5.3~\mathrm{g}$ of the powder in enough water to make $250~\mathrm{mL}$ of solution. Find the molar concentration.
I have done ...
3
votes
4answers
2k views
Does the addition or multiplication rule have precedence deciding the significant figures in 5×5.364? [duplicate]
How many significant figures should be present in the answer of
$5\times 5.364$?
Addition rule: The result cannot have more digits to the right of the decimal point than either of the original ...
1
vote
1answer
2k views
the number of significant figures
An electronic balance was used to determine that a sample has a mass of 9.00060 g. If the balance's precision is ± 1 mg, what is the correct number of significant figures for this measurement?
...
0
votes
1answer
150 views
How to calculate concentrations and what is the concept of 'mole'?
Say I have a $50~\mathrm{ml}$ solution of a liquid mixture which is $30~\%$ concentrated. Now if I take $20~\mathrm{ml}$ of that liquid out from that mix, what would be the resulting concentration of ...
2
votes
0answers
63 views
How to define a flame in numerical combustion?
I am running a CFD simulation (computational fluid dynamics) opposed jet case, where a stream of fresh reactants is opposed to a stream of burnt products. I am looking at the effects of stratification ...
1
vote
1answer
3k views
Propagation of the uncertainty in measurements
The inside dimensions of a box that is cubic is 12.7 cm on each edge with an uncertainty of 0.3 cm.
What is the volume of the box?
What do you estimate to be the uncertainty in the calculated volume?
...
0
votes
1answer
7k views
Convert grams of water to steam
I'm working through problems in my textbook. How much heat is required to convert 2.55 g of $\ce{H2O}$ at 28 °C to steam at 100 °C?
In simpler problems I've used the fact that $\Delta H_\text{fus} = ...
5
votes
1answer
5k views
Calculate the number of moles produced per hour per liter of air?
A reaction of importance in the formation of smog is that between ozone and nitrogen monoxide described by
$$
\ce{O3(g) + NO(g)->O2(g) + NO2(g)}
$$
the rate law for this reaction is:
$$
\text{...
12
votes
1answer
47k views
How do I round a calculation involving both addition/subtraction and multiplication/division to the correct number of significant figures?
I'm just learning about significant figures (sig figs) in my chemistry class, and I'm confused about the rules. An example to my problem: if I had the following expression:
$$\left ( \frac{2.378 - 1.2}...
