Question

Умоляю люди , помогите пожалуйста несколько задании по химии 1. Что ошибочно для элементов главной подгруппы II группы ? а) s-элементы в) имеют 2 валентных электрона с) проявляют степень окисления +2 д) все они называются щелочноземельными металлами е) менее активны , чем щелочей метал , расположенный в том же периоде 2. Что верно верно для кальция? 1.тяжелый металл 2. более сильный восстановитель , чем водород 3. активнее магния 4. пламя окрашивает в кирпично-красный цвет 5. в природе встречается в свободном состоянии и в виде соединений 3. Почему металлический кальций не получают восстановливанием негашеной извести (CaO) водородом или углеродом ?

Answer 1

1 - д ( щелочноземельными называются только ( кальций,стронций,барий,радий)

Answer 2

Elements of the Main Group II Group

The elements of the main group II group, also known as the alkaline earth metals, have certain characteristics. Let's go through the given options and determine which one is incorrect:

a) S-elements: This statement is correct. The elements of the main group II group are often referred to as s-elements because their valence electrons are located in the s-orbital of their outermost energy level.

b) 2 valence electrons: This statement is correct. The elements of the main group II group have 2 valence electrons.

c) Oxidation states: This statement is incorrect. The elements of the main group II group typically exhibit a +2 oxidation state. For example, calcium (Ca) commonly forms Ca^2+ ions.

d) Alkaline earth metals: This statement is correct. All the elements of the main group II group are commonly referred to as alkaline earth metals.

e) Less active than alkali metals: This statement is correct. The elements of the main group II group are generally less reactive than the alkali metals, which are located in the same period.

Based on the given options, the incorrect statement for the elements of the main group II group is c) they exhibit oxidation states [[1]].

Calcium Properties

Let's now discuss the properties of calcium and determine which statements are true:

1. Heavy metal: This statement is incorrect. Calcium is not considered a heavy metal. It is an alkaline earth metal with a relatively low atomic mass.

2. Stronger reducing agent than hydrogen: This statement is correct. Calcium is a stronger reducing agent than hydrogen. It readily loses its two valence electrons to form Ca^2+ ions, which can act as reducing agents in certain chemical reactions.

3. More active than magnesium: This statement is correct. Calcium is more active than magnesium. It reacts more readily with certain substances due to its larger atomic size and lower ionization energy.

4. Flame color: This statement is incorrect. Calcium does not produce a brick-red flame color. Instead, it produces a brick-red color when it is used as a flame test reagent.

5. Occurs in nature and in compounds: This statement is correct. Calcium is found in nature in various forms, including as calcium carbonate (CaCO3) in limestone and as calcium sulfate (CaSO4) in gypsum.

Based on the given options, the correct statements for calcium are 2. it is a stronger reducing agent than hydrogen and 5. it occurs in nature and in compounds [[2]].

Production of Metallic Calcium

The production of metallic calcium through the reduction of unslaked lime (CaO) with hydrogen or carbon is not a common method. While it is theoretically possible to reduce calcium oxide with hydrogen or carbon, it is not a practical method for producing metallic calcium.

The reduction of calcium oxide with hydrogen or carbon requires high temperatures and specific reaction conditions that are difficult to achieve in practice. Additionally, the reaction may not proceed efficiently, and impurities may be introduced during the process.

Instead, metallic calcium is typically produced through the electrolysis of calcium chloride (CaCl2) or by the thermal reduction of calcium oxide with aluminum in a process called the aluminothermic reaction.

Therefore, the reason why metallic calcium is not obtained by reducing unslaked lime (CaO) with hydrogen or carbon is due to the impracticality and inefficiency of the process [[3]].

I hope this helps! Let me know if you have any further questions.