The p H o f 0.15 M N H 4 C l ( a q ) has to be calculated taking into account the autoprotolysis of water. Concept Introduction: The contribution of autoprotolysis of water to the calculation of p H of very dilute solutions of weak acid must be taken into consideration if the hydronium ion concentration is less than 10 − 6 M . For very dilute solutions of weak acid, the given below equation should be used. [ H 3 O + ] 3 + K a [ H 3 O + ] 2 − ( K W + K a [ H A ] I n i t i a l ) [ H 3 O + ] − K a K W = 0

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Chapter 6, Problem 6F.7E

Interpretation Introduction

Interpretation:

The pH of 0.15MNH4Cl(aq) has to be calculated taking into account the autoprotolysis of water.

Concept Introduction:

The contribution of autoprotolysis of water to the calculation of pH of very dilute solutions of weak acid must be taken into consideration if the hydronium ion concentration is less than 10−6M.

For very dilute solutions of weak acid, the given below equation should be used.

[H3O+]3+Ka[H3O+]2−(KW+Ka[HA]Initial)[H3O+]−KaKW=0

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