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HCL 1.14 H3PO4 1.69 HC2H3O2 2.84 NaH2PO4 4.40 Al(NO3)3 3.15 Zn(NO3)2 5.84 NH4NO3

ID: 1014401 • Letter: H

Question

HCL              1.14

H3PO4         1.69

HC2H3O2    2.84

NaH2PO4      4.40

Al(NO3)3                            3.15

Zn(NO3)2                           5.84

NH4NO3                            5.12

Vinegar 2.31

Carbonate Water              5.30

Tap Water                          7.56

Distilled Water                 4.56

1. a Calculate the concentrations of H3O+ ions in the most acidic solution that you examined. Use your most precise pH measurment.

b. Calculate the concentrations of H3O+ ions in the least acidic solution that you examined. Use your most precise pH measurement.

Explanation / Answer

(a) A solution is most acidic if its pH value is low

Among the given list the most acidic solution pH is 1.14 that is for HCl solution

pH = 1.14

- log[H3O+] = 1.14

[H3O+ ] = 10-1.14 = 0.072 M

HCl + H2O ----> H3O+ + Cl-

1 mole of HCl produces 1 mole of H3O+

So [H3O+ ] = 0.072 M

(b) A solution is least acidic if its pH value is high & it is less than 7

Among the given list the least acidic solution pH is 5.84 that is for Zn(NO3)2 solution

pH =5.84

- log[H3O+] = 5.84

[H3O+ ] = 10-5.84 = 1.44x10-6 M

Zn(NO3)2 + 2H2O ----> Zn(OH)2 + 2HNO3

1 mole of Zn(NO3)2 produces 2 moles of HNO3 and 2 moles of HNO3 contains 2 moles of H3O+

So 2x[H3O+ ] = 1.44x10-6 M

        [H3O+ ] = 7.23x10-7 M