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Comment turned to answer: Because it has been mixed. Each substance is now in doubled volume, compared to volume before mixing. If you had whiskey and if you mixed it with the same volume of soda, it wouldn't have the same strength as before, would it ?


Water is very unique liquid, because it has a higher density in the liquid state than the solid state. The maximum density of water is found at $\pu{4 ^\circ C}$, which is reported as $\pu{999.9720 kg\:m^{-3}}$ (Temperature Effects on Density). Therefore, molarity of water at $\pu{4 ^\circ C}$ can be calculated as $\frac{\pu{999.9720 g\:L^{-1}}}{\pu{18.015 g\...


I think you have confused amount of substance with molarity of the solution. For example: $\ce{NaOH}$ solution with $\pu{1M}$ in molarity means $\pu{1L}$ of solution contains $\pu{1mol}$ of $\ce{NaOH}$. You can calculate amount of $\ce{NaOH}$ in any volume of the solution by multiplying its molarity and required volume in $\pu{L}$: $$\text{Amount of }\ce{...


There is problem with ppx values they are ambiguous. It may be w/w, w/v, v/v, n/n. Salt water has density significantly different to $\pu{1 g/ml}$, so $\pu{1 ppt(parts per thausand) }$ may mean $\pu{1000 mg/L}$ or $\pu{1000 mg/kg}$, with the recalculation factor of the solution density. The former ($\pu{ppt w/v as 1000 mg/L}$) is more probable, but check ...


First, when solving problems like this one, you have to make sure that both salts possess good solubility and that no double salt is precipitating: $$ \begin{align} \ce{NaNO3 &<=>> Na+ + NO3-}\label{rxn:R1}\tag{R1}\\ \ce{Ca(NO3)2 &<=>> Ca^2+ + 2NO3-}\label{rxn:R2}\tag{R2} \end{align} $$ Both nitrates are indeed well soluble in ...


$$\pu{1 mg L-1} = \pu{1 ppm} = \frac{1}{1000}\cdot\pu{ppt}$$ or $$\pu{1 ppt} = \pu{1000 ppm}$$ For example: $$\pu{10 ppm} = \frac{10}{1000}~\pu{ppt} = \pu{0.01 ppt}\tag{1}$$ $$\pu{5 ppt} = 5\cdot\pu{1000 ppm} = \pu{5000 ppm}\tag{2}$$

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