Question

can you please. fill in the charts by putting the change of ph and and answer the 3 question please thank you

Data: Table A: Water Change in Initial pH pH after addition of addition of addition of pH 0.1M HNO3 | 0, 1 MINaOH | distilled pH after H after water Beaker A Beaker B Beaker C ヌ·13 ヌ12 Table B: Buffer Initial pH pH after pH after pH after Change in addition of addition of addition of pH 0.1M HNO3 0.1M NaOH distilled water 4-14 Beaker A Beaker B Beaker C Table B: Acid Initial pH pH after pH after pH after Change in addition of addition of addition of pH 0.1M HNO3 0.1M NaOH distilled water |スら丁 ス. Beaker A Beaker B Questions: 1. Compare how the three solutions react to the addition of an acid. Compare how the three solutions react to the addition of a base. Compare how the three solutions react to the addition of distilled water. 2. 3. Data: Table A: Water Change in Initial pH pH after addition of addition of addition of pH 0.1M HNO3 | 0, 1 MINaOH | distilled pH after H after water Beaker A Beaker B Beaker C ヌ·13 ヌ12 Table B: Buffer Initial pH pH after pH after pH after Change in addition of addition of addition of pH 0.1M HNO3 0.1M NaOH distilled water 4-14 Beaker A Beaker B Beaker C Table B: Acid Initial pH pH after pH after pH after Change in addition of addition of addition of pH 0.1M HNO3 0.1M NaOH distilled water |スら丁 ス. Beaker A Beaker B Questions: 1. Compare how the three solutions react to the addition of an acid. Compare how the three solutions react to the addition of a base. Compare how the three solutions react to the addition of distilled water. 2. 3.

Answer 1

Hey There,

1. I am assuming that you are adding same amount of acid, Base and salt to the solution so as to compare the effect.
2. I think there have been some error(Instrumental or Human error) while taking Two measurements as in case of Water pH changed very less on addition of NaOH wheras it changed drastically on addition of HNO₃.
3. I am assuming the Buffer to be of Acetic Acid(Weak Acid) ${\color{Blue} CH_3COOH\rightleftharpoons CH_3COO^-+H^+}$ and Sodium Acetate(Conjugate ion salt) ${\color{Blue} CH_3COONa\rightarrow CH_3COO^-+Na^+}$ .where CH₃COO^- is the Common ion.

Answer 1

in case of water, on addition of Stron acid HNO₃, the acid dissociates completely as

${\color{Blue} HNO_3+H_2O\rightarrow H_3O^++NO_3^-}$

and as H⁺ concentration increases, the pH decreases drastically( pH=-log[H⁺])

in case of Buffer

on adding Acid, pH changes very little as inthe buffer the conjugate ion combines with the H⁺ and hence it's concentration doesn't change which doesnot change pH

${\color{Blue} CH_3COO^- + H^+\rightarrow CH_3COOH}$

in case of acid

it now depends on the overall concentration of H⁺ that the pH will decrease or increase. if a dilute acid is added to concentrated acid,the overall pH will increase as the dilution increases which decrease the H⁺ concentration.

and if concentrated acid is added to the dilute acid, the pH decreases as the [H⁺] increases. but the pH change will not be drastic

Answer 2

in case of water

NaOH is as strongbase and it dissociates completelyin water and due to it the pH must increase drastically of water due to increase in OH^- Concentration

${\color{Blue} NaOH\rightarrow Na^++OH^-}$

but in the experiment done by you, the pH increase slightly which may be due to several factors

• Less amount of NaOH solution added.
• not standard solution of NaOH used.
• experimental or instrumental error.

in case of Buffer

in case of the buffer, the pH is very less altered as buffer always resist the pH change due to it's constituents. Here acid Base reaction occurs and the H⁺ and OH^- concentration remain unaltered

${\color{Blue} CH_3COOH + OH^-\rightarrow CH_3COO^- + H_2O}$

and hence the excess OH^- are removed resulting in the approximately constant pH of solution.

in case of Acid

Since the acid solution comprises of excess H⁺ ions and these ion leads to decrease in pH. on addition of Base the OH^- concentration increases, which result in the

${\color{Blue} H^+ + OH^-\rightarrow H_2O}$

so the [H⁺] decreases and pH of the solution increases

Answer 3

in case of water

Since you are adding water in the water, the pH must remain unaltered as the concentration of H⁺ is same in both water samples (at 298K 10^-7M). But here also I sense some sort of error which may be same to Answer 2 or the beaker or the pH meter not cleaned properly.

in case of Buffer

the addition of water increases the H⁺ and OH^- equally and hence the overall pH is affected very less. But the overall concentration of every ion decreases and hence the pH must increase by a little value and thatis observed.

in case of Acid

on addition of water to Acid, the dilution and the [H⁺] remains practically unchangedso the pH remain nearly same

Hope I Answered

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