New answers tagged concentration
0
Solving one out of the four would be good enough to understand the concept behind this. Therefore, I shall explain the first experiment and the concentrations of the components in the solution produced.
In experiment 1 all four are added in equal quantities. Finding the total volume, we get the total volume
$$V_\text{tot} = \pu{4 ml}.$$
Assuming the amount ...
3
Here's one way you could get from eqn. (2) to eqn. (3) in porphyrin's answer using Mathematica. I made extensive use of the Part function, whose shorthand is "[[ ]]", to pull out the desired subexpression from each answer.
E.g., Part[x+y, 1], which means "take the first part of the expression (x+y)", can be expressed as (x+y)[[1]], and ...
4
The general second order equation is
$$\frac{\mathrm d[A]}{\mathrm dt}=-k[\ce{A}][\ce{B}]\tag{1}$$
with $[\ce{A}]_0,$ $[\ce{B}]_0$ the initial amounts. At a time $t$ there are $[\ce{A}]_0-x$, and $[\ce{B}]_0-x$ remaining if amount $x$ reacts. Thus
$$\frac{\mathrm dx}{\mathrm dt}=k([\ce{A}]_0-x)([\ce{B}]_0-x).\tag{2}$$
You should be able to integrate this ...
2
How to calculate molar concentration from equilibrium equations with no initial concentration given?
I will continue with the data of $[\ce{H2CO3}] = \pu{10^{-4.97} M}.$
Now, as the $K_2$ of $\ce{H2CO3}$ is very small as compared to its $K_1,$ we can assume that all the $\ce{H+}$ will come from the first dissociation of $\ce{H2CO3}.$
$$
\begin{array}{lccc}
& \ce{&H2CO3 &<=> &H+(aq) &+ &HCO3-(aq)} \\
&\text{Initial} & ...
0
Try to report first the logarithm of the concentration of the reagent versus the time $t$. If it gives perfectly aligned points, going downwards, the kinetics is first order, and the slope of the line is the rate constant $k_1$ in $\pu{s^-1}.$
If the points are not aligned on the logarithmic curve, try to report the inverse $1/c$ of the concentration of the ...
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Assuming the water is at the same temperature and pressure on both sides, the only way to create a difference in pH would be through the presence of conjugate acids and/or bases other than $\ce{H_2O}$, $\ce{H^+}$ and $\ce{OH^-}$. I.e., you can't have pure water at the same temperature and pressure on both sides, yet have a difference in pH. [Pressure would ...
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In this situation, "sensitivity" refers to how often the test is able to correctly detect the presence of analyte. A test with high sensitivity means that there are few false negatives.
Limit of detection refers to how much of the analyte must be present before it is considered positive.
Imagine two different tests: test A uses an antibody with ...
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