The pH Scale Learning Goal: To calculate pH and use it as a measure of acidity.

Question

The pH Scale Learning Goal: To calculate pH and use it as a measure of acidity. The pH expresses the molar concentration of hydronium ions in an aqueous solution on a logarithmic scale: pH log Hao 10-pH CH30 As pH decreases, acidity increases. As pH increases, acidity decreases. Acidic solution: pH 7 Neutral solution: pH Basic solution: pH 7 Part B Carbonated cola is more acidic than coffee or even orange juice because cola contains phosphoric acid. What is the molar concentration of H3O+ in a cola that has a pH of 3.120? Express your answer with the appropriate units. CH30 Value Units Submit Hints My Answers Give Up Review Part Incorrect, Try Again, 5 attempts remaining Part C Rank the following from most to least acidic. Rank from most to least acidic. To rank items as equivalent, overlap them. H301 10 Most acidic Least acidic

Explanation / Answer

We know pH = -log [H3O+]

Log [H3O+] = -pH

[H3O + ] = Antilog (-3.120)

= 0.0007585

= 7.585 X10-4 mol/L

2)

pH = -log [H3O+]

Lets convert all in pH

[H3O+] = 10-2

pH = -log ( 10-2)

=2

[H3O+ ] = 10-5

pH = -log 10-5

= 5

We know as pH is increasing acidity is decreases

Least to most acidic :

pH = 9 < pH 5 < pH 4 < pH 2.5 < pH 2

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