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To sum up the comments, only the following relation for the total amount of solution $n_\mathrm{tot}$ is universally true: $$n_\mathrm{tot} = n_\mathrm{solvent} + n_\mathrm{solute} = \frac{m_\mathrm{solvent}}{M_\mathrm{solvent}} + \frac{m_\mathrm{solute}}{M_\mathrm{solute}}\tag{1}$$ The best you can do is to assume that $n_\mathrm{tot}\approx n_\mathrm{...


3

Let consider ratio of N/P. Let fertilizer A has this ratio N/P=a. Let fertilizer B has this ratio N/P=b. Let you want the ratio c, where a < c < b. Then you need to mix A : B in ratio $$\frac{ b - c}{c-a}$$ In the Central Europe with German scientific influence, it is called the "mixing cross rule". Note that you can chose just ratio of 2 ...


1

Iodine itself has a comparatively high vapor pressure, ~40 Pa at room temperature, so iodine solutions, e.g. tincture of iodine (iodine in ethanol/water), lose iodine by evaporation (well, by sublimation, from the solid). This just means that the strength of the antiseptic is reduced if left open, not that it has not "gone bad," in the sense of ...


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A solution of iodine antiseptic is a medical item that is used for improving health. There are two ways to treat your cracked cap. #1. If you inspected the bottle in the drug store before you bought it, you would not buy this bottle. Almost all over-the-counter medicines have warnings: Do not use if the safety seal is broken. So, out of utmost caution, do ...


1

Total mole fractions of a system are known, constant and can be measured or calculated at/for any time ( no reaction is assumed ). Mole fractions within a gaseous or liquid phase are measured or calculated in context of Raoult law for the state of equilibrium, unless they are defined as an initial state for a particular scenario.


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If there is no further clarification in the specification of the 10% (like 10vol% or 10mol%), then this should indicate a mass fraction. Thus, 10% of the mass of the solution is supposed to be $\ce{KOH}$, so you would dissolve 10 g in 90 g ethanol to get the desired solution. I don't know the precise solubility of $\ce{KOH}$ in ethanol but I assume that, if ...


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