Copper sulphate (CuSO4) is a salt derived from a strong acid (H2SO4) and a weak base (Cu(OH)2). Upon hydrolysis in water, it produces acidic ions, resulting in an acidic solution that turns blue litmus paper red.
3802
Which substance is commonly ingested to neutralize excess stomach acidity?
Acidity is caused by an excess of hydrochloric acid in the stomach. Baking soda (sodium bicarbonate) is a mild base that reacts with the excess acid to neutralize it, producing water, carbon dioxide, and sodium chloride, thereby providing relief from the symptoms of indigestion.
3803
What chemical change occurs as the pH value of a solution increases from 7 to 14?
The pH scale is logarithmic. As pH increases from 7 (neutral) to 14 (strongly basic), the concentration of hydrogen ions [H+] decreases significantly, while the concentration of hydroxide ions [OH-] increases. Both options A and B describe the trend, but B specifically highlights the increase in basicity characteristic of the higher pH range.
3804
When sodium carbonate (Na2CO3) is dissolved in water, the resulting reaction produces sodium hydroxide (NaOH) and carbonic acid (H2CO3). Which term best describes this chemical process?
Hydrolysis is a chemical reaction in which water is used to break down the bonds of a particular substance. In the case of sodium carbonate, the carbonate ion (CO3^2-) reacts with water molecules to form bicarbonate ions and hydroxide ions. This interaction between the salt's ions and water, which alters the pH of the solution, is specifically classified as salt hydrolysis, distinguishing it from simple dissociation or ionization processes.
3805
How does the acidity of the soil affect the color of Hydrangea macrophylla flowers?
The color of Hydrangea macrophylla flowers is dependent on the pH of the soil. In acidic soil (pH below 6), aluminum ions are more available to the plant, which results in blue flowers. In alkaline or neutral soil, the aluminum is less available, leading to pink or red flowers. Therefore, treating soil with an acidic substance promotes the blue color.
3806
The pH value of an aqueous solution is primarily determined by the concentration of which species?
The pH scale is defined as the negative logarithm of the hydronium ion concentration, [H3O+], in an aqueous solution. While hydroxyl ions ([OH-]) are related through the ion product of water (Kw), the direct measurement of acidity is based on the hydronium ion concentration.
3807
If a salt solution has a pH value of 12, it is likely derived from which combination of acid and base?
A pH of 12 indicates a basic solution. Salts that produce basic solutions are formed from the reaction of a weak acid and a strong base. The strong base component dominates the hydrolysis process, resulting in an excess of hydroxide ions in the aqueous solution.
3808
What is the approximate pH value typically associated with fresh lemon juice?
Lemon juice contains a high concentration of citric acid, which makes it significantly acidic. The pH scale ranges from 0 to 14, where values below 7 indicate acidity. Lemon juice typically exhibits a pH in the range of 2.0 to 2.6, making 2.2 the most accurate representative value among the given options.
3809
What is the standard pH value of pure water at 25 degrees Celsius?
At 25 degrees Celsius, pure water is neutral, meaning the concentration of hydrogen ions (H+) equals the concentration of hydroxide ions (OH-). The negative logarithm of the hydrogen ion concentration (10^-7 M) results in a pH value of exactly 7.
3810
Which substance is effective for neutralizing the formic acid injected during an ant bite?
Ant bites inject formic acid into the skin, causing irritation. Sodium bicarbonate (baking soda) is a mild base that reacts with the acid to neutralize it, thereby alleviating the pain and swelling associated with the sting.
