Answer:
[tex][H^+]=1x10^{-7}M[/tex]
Explanation:
Hello.
In this case, since the reaction between sodium hydroxide and hydrochloric acid has a 1:1 mole ratio between them:
[tex]NaOH+HCl\rightarrow NaCl+H_2O[/tex]
In order to compute the hydronium H⁺ concentration in the mixed volumes of the given solutions we first compute the moles of each reactant:
[tex]n_{NaOH}=0.750L*0.10mol/L=0.075mol\\\\n_{HCl}=0.250L*0.30mol/L=0.075mol[/tex]
As seen, since those amounts are the same, we infer all the acid and base are consumed so the pH is 7 because a neutral salt is produced, and the corresponding H⁺ concentration is:
[tex][H^+]=10^{-pH}=10^{-7}=1x10^{-7}M[/tex]
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