【People's Education Press】High School Chemistry: Compulsory Course 1: From Seawater Salt to Reactive Elements – A Macroscopic Introduction to Sodium and Chlorine

From the 'Ocean Treasury' to the 'Frontiers of Chemistry'

Approximately 71% of Earth's surface is covered by oceans. This vast blue expanse is not only the cradle of life, but alsoa treasure trove of elementsAmong the ions in seawater, beyond water molecules, the most abundant are $Na^+$ and $Cl^-$. They exist in nature in an extremely stable form—table salt (NaCl). Yet, the chemist’s mission is to 'transform the ordinary into the extraordinary'.

Just as the Swedish chemistScheele (C.W. Scheele)first captured yellow-green chlorine gas from a reaction between hydrochloric acid and manganese dioxide in 1774, modern industry converts stable compounds into highly reactive elements through the electrolysis of molten sodium chloride. This transformation exemplifies the core principle of chemical research:Structure Determines PropertiesWe will uncover the mysteries of these reactive elements through the path of 'Experimental Observation → Property Prediction → Scientific Verification'.

Research Methodology: Macroscopic Identification and Microscopic Analysis

When encountering unknown substances, we follow the following scientific logic:

Observe its color, state, hardness, and otherphysical properties.
Predict itschemical reactivity.
Verify itsoxidizing or reducing properties.

QUESTION 1

[Reading Comprehension] Fuel cells are chemical batteries with advantages such as high energy conversion efficiency and environmental friendliness. They can replace gasoline to power vehicles or serve as lighting sources. After reading the above popular science article, what is the fundamental mechanism by which this battery achieves energy conversion?

Thermal energy converted to electrical energy

Chemical energy directly converted to electrical energy

Mechanical energy converted to chemical energy

Solar energy converted to biological energy

QUESTION 2

[Fill in the Blanks] (1) The main chemical properties of acids are summarized below. Complete the reaction chain as required: $Ca \rightarrow CaO \rightarrow Ca(OH)_2 \rightarrow CaSO_4$. To achieve the transformation from $CaO \rightarrow Ca(OH)_2$, the reagent to be added is ____; to achieve $Ca(OH)_2 \rightarrow CaSO_4$, dilute sulfuric acid can be added—the chemical equation for this reaction is ____.

$H_2O$; $Ca(OH)_2 + H_2SO_4 = CaSO_4 + 2H_2O$

$HCl$; $Ca + H_2SO_4 = CaSO_4 + H_2$

QUESTION 3

[Multiple Choice] Regarding the reaction between iron and copper sulfate solution: $Fe + CuSO_4 = FeSO_4 + Cu$, which of the following statements is correct?

A. This reaction indicates that iron has stronger metallic activity than copper

B. The ionic equation for this reaction is: $Fe + Cu^{2+} = Cu + Fe^{2+}$

C. This reaction is a redox reaction, and iron is oxidized during the process

D. This reaction suggests that all metal elements can react with salts

QUESTION 4

The core question raised in this lesson is: 'What are the properties of sodium and chlorine elements and their compounds? How should we conduct our research?' Which of the following is NOT a standard procedure for studying element properties?

Observation of physical properties

Prediction and experimental verification of chemical properties

Using the Book of Changes (I Ching) to infer properties

Classification, summary, and structural analysis

QUESTION 5

Which of the following correctly describes the physical properties of sodium?

High hardness, cannot be cut with a knife

Silvery-white metal, density lower than water

Liquid at room temperature

Non-conductive