Properties of Alkali Metals (Group 1A)

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Questions and Answers

Which of the following is a characteristic of alkali metals?

Low ionization energy (correct)

High electronegativity

Small atomic radius

Strong metallic bond

What is the oxidation state of alkali metals?

-2

+1 (correct)

-1

What is the use of potassium superoxide (KO2)?

To produce oxygen

To remove CO2

To purify air (correct)

To produce hydrogen

What is the property of alkali hydrides?

Reducing agent Signup and view all the answers

What is the use of sodium nitrate?

To remove hardness of water Signup and view all the answers

What is the byproduct of the reaction between sodium chloride and ammonia?

NH4Cl Signup and view all the answers

What is the property of ammonia?

Colorless and lighter than air Signup and view all the answers

What is the use of Cu in the industrial preparation of Na2CO3?

To remove oxygen Signup and view all the answers

What is the reaction between lithium and nitrogen?

Li + N2 → Li3N2 Signup and view all the answers

What is the primary reason for the weak metallic bond in alkali metals?

Due to their single valence electron Signup and view all the answers

Which of the following compounds is used to remove hardness of water?

Na2CO3 Signup and view all the answers

What is the primary function of mercury in the industrial preparation of Na2CO3?

To collect nitrogen Signup and view all the answers

What is the result of the reaction between alkali nitrates and water?

Decomposition of the nitrate Signup and view all the answers

What is the reason for the high boiling point of ammonia?

Due to its ability to form hydrogen bonds Signup and view all the answers

What is the byproduct of the reaction between sodium chloride and carbon dioxide in the industrial preparation of Na2CO3?

NH4Cl Signup and view all the answers

What is the purpose of using hydrogen sulfate in the industrial preparation of Na2CO3?

To dehydrate water Signup and view all the answers

What is the result of the reaction between alkali hydrides and water?

Formation of hydrogen gas Signup and view all the answers

What is the characteristic of alkali metals that makes them electropositive?

Their ability to lose one electron Signup and view all the answers

Study Notes

Alkali Metals (Group 1A)

Have 1 valence electron, which they lose to form a +1 oxidation state, making them reducing agents
Electropositive, with weak metallic bonds due to their single valence electron
Have large radii, small electron affinities, low first ionization energies, and low electronegativities
Form ionic compounds

Compounds of Alkali Metals

Potassium superoxide (KO2) is used to purify air, taking in CO2 and producing O2
Peroxides and superoxides are oxidizing agents, reacting with water or acid to produce O2
Alkali hydrides are reducing agents, reacting with water or acid to produce H2
Alkali nitrates decompose, such as potassium nitrate (salt peter)
Sodium nitrate is hygroscopic, absorbing water vapor from the air

Industrial Preparation of Sodium Carbonate (Na2CO3)

Used to remove water hardness by precipitating Mg and Ca ions
Prepared through the Solvay process: NaCl + CO2 + H2O + NH3 → NH4Cl + NaHCO3
NaHCO3 is then heated to produce Na2CO3 + H2O + CO2
NaOH is used to remove CO2, Cu to remove oxygen, H2SO4 to dehydrate water, and Hg to collect nitrogen

Ammonia (NH3)

Prepared in the lab: 2NH4Cl + Ca(OH)2 → CaCl2 + 2H2O + 2NH3
Alternatively, prepared industrially: NH3 + LiOH → LiNH2 + H2O
Colorless, lighter than air, dissolves in water, and has a high boiling point due to hydrogen bonds
A base, turning blue litmus paper red, and reacts with acids to form ammonium salts
Anhydrous NH3 is prepared by reacting nitrogen with lithium: Li + N2 → Li3N + H2O

Haber-Bosch Process

Used to produce ammonia on a large scale: N2 + H2 → 2NH3
Calcium cyanamide (CaCN2) is also used in this process

Alkali Metals (Group 1A)

Valence electron: 1, loses 1 electron to form +1 oxidation state
Reducing agent, electropositive (Na+)
Weak metallic bond due to 1 valence electron
Large radius, small electron affinity, low first ionization, and low electronegativity

Compounds of Alkali Metals

Potassium superoxide (KO2): used to purify air, takes CO2 and produces O2
Peroxides and superoxides: oxidizing agents, react with water or acid to produce O2
Alkali hydrides: reducing agents, react with water or acid to produce H2
Alkali nitrates: decompose (e.g., potassium nitrate, salt peter)

Sodium Compounds

Sodium nitrate: hygroscopic, absorbs water vapor from air
Sodium carbonate (Na2CO3): used to remove water hardness by precipitating Mg and Ca, industrially prepared by Solvay process
Sodium hydroxide (NaOH): used to remove CO2, Cu is used to remove oxygen, H2SO4 is used to dehydrate water, and Hg is used to collect nitrogen

Ammonia

Prepared from nitrogen: industrial preparation involves NH3CI + NaNO2, lab preparation involves 2NH4Cl + Ca(OH)2
Properties: colorless, lighter than air, dissolves in water, polar, high boiling point due to hydrogen bonds
Reacts with acids to form ammonium (NH4+), turns blue litmus paper to red
Uses: anhydride, Haber-Bosch process, and CaCN2 reaction

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Description

Learn about the general properties of alkali metals, including their valence electrons, oxidation states, and reactivity. This quiz covers the characteristics of group 1A elements, such as sodium and potassium, and their compounds.