Question

SECOND TERM 2021/2022 HOLIDAY ASSIGNMENT

SUBJECT: CHEMISTRY CLASS SS1

1 (a) Define a salt

(b) The basicity of tetraoxosulphate VI acid is 2. Explain this statement with equation showing

the reaction between the acid and potassium hydroxide

2. Define buffer solution and give two uses of buffer solutions.

3. Explain and give an example each of

(a) Hygroscopy (b) Efflorescence (c) Deliquescence

4. The concentration of hydrogen ion H⁺ in two solutions are:

(a) 1 x 10⁻³moldm⁻³ and (b) 6 x 10⁻⁹moldm⁻³

What is the pH of each solution?

5. (a) Give three crystalline and four non-crystalline allotropes of carbon

(b) Give three differences between the two main crystalline allotropes of carbon.​

Answer 1

1.

a) Salt: any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation.

Acid + alkali → salt + water

b)

Tetraoxosulfate (VI), SO2−4,SO42−, is the second conjugate base from the dissociation of sulfuric acid, H2SO4.H2SO4. This acid is a diprotic acid and thus can donate two protons in an aqueous solution to form HSO−4HSO4− after the first dissociation and SO2−4SO42− after the second dissociation.

The fact that tetraoxosulfate (VI) is dibasic means in terms of Brønsted-Lowry acid-base theory, the ion can accept two protons, or in other words, the parent acid donates two protons upon dissociation. This can be shown by the equation of the reaction between the parent sulfuric acid and potassium hydroxide where two hydrogens are replaced:

H2SO4+2KOH → K2SO4+2H2O

2. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical applications. In nature, there are many systems that use buffering for pH regulation.

For example, blood in the human body is a buffer solution.

Buffer Solutions are used for fermentation in the making of alcohol


I've only answered 1 & 2