Non-metals are chemical elements that generally do not possess the properties of metals. They occupy the upper right corner of Mendeleev's Periodic Table of Elements and are usually separated by a line (a "staircase"). The number of non-metals is 22–23 elements, depending on the classification.

A characteristic feature of non-metals is the greater (compared to metals) number of electrons in the outer energy level of their atoms. This determines their greater ability to add extra electrons and their higher oxidizing activity compared to metals.

Twenty-three elements are considered non-metals. Fourteen elements are almost always recognized as such: hydrogen, oxygen, nitrogen, and sulfur; the corrosion-active halogens: fluorine, chlorine, bromine, and iodine; and the noble gases: helium, neon, argon, krypton, xenon, and radon; as well as carbon, phosphorus, and selenium

Task 1. Carry out the reaction between solutions of:

• a) sodium sulfate and barium nitrate;
• b) sodium chloride and silver(I) nitrate.

Describe the signs of the reactions. Indicate the anions contained in the resulting precipitates.

Let's work through both reactions step by step.

a) Sodium sulfate + barium nitrate

Reaction equation:

$N{a}_{2}S{O}_4+Ba(N{O}_3{)}_2\to BaS{O}_4\downarrow +2NaN{O}_3$​

Sign of the reaction:
— a white insoluble precipitate forms.

What this precipitate is:
— barium sulfate $BaS{O}_4$​

Anion contained in the precipitate:
— $S{O}_4^{2-}$ (sulfate ion)

b) Sodium chloride + silver(I) nitrate

Reaction equation:

$NaCl+AgN{O}_3\to AgCl\downarrow +NaN{O}_3$​

Sign of the reaction:
— a white curdy precipitate forms (may darken in light).

What this precipitate is:
— silver chloride $AgCl$

Anion contained in the precipitate:
— $C{l}^{-}$Cl− (chloride ion)

Summary:

• In the first reaction, the precipitate contains the anion $S{O}_4^{2-}$​

• In the second reaction, the precipitate contains the anion $C{l}^{-}$

Task 2. Carry out reactions proving the qualitative composition of:

• a) ammonium chloride;
• b) sulfuric acid.

Here is how to carry out qualitative reactions to determine the composition of substances

a) Ammonium chloride (NH₄Cl)

It is necessary to prove the presence of:

• the cation NH₄⁺ (ammonium)

• the anion Cl⁻ (chloride)

1. Proof of NH₄⁺

Reaction with alkali (NaOH):

NH₄Cl + NaOH → NH₃↑ + NaCl + H₂O

Signs:

• ammonia gas (NH₃) with a pungent odor is released

• moist red litmus paper turns blue

2. Proof of Cl⁻

Reaction with silver nitrate (AgNO₃):

NH₄Cl + AgNO₃ → AgCl↓ + NH₄NO₃

Signs:

• a white precipitate of AgCl (silver chloride) forms

b) Sulfuric acid (H₂SO₄)

It is necessary to prove the presence of:

• the cation H⁺

• the anion SO₄²⁻ (sulfate)

1. Proof of H⁺

Reaction with a metal (for example, Zn):

Zn + H₂SO₄ → ZnSO₄ + H₂↑

Signs:

• hydrogen gas (H₂) is released

• a "hiss" is heard, gas bubbles appear

2. Proof of SO₄²⁻

Reaction with barium chloride (BaCl₂):

H₂SO₄ + BaCl₂ → BaSO₄↓ + 2HCl

Signs:

• a white insoluble precipitate of BaSO₄ (barium sulfate) forms

Summary:

• NH₄Cl → NH₃ (gas) + AgCl (precipitate)

• H₂SO₄ → H₂ (gas) + BaSO₄ (precipitate)

Task 3. Use qualitative reactions to identify the solutions given to you in numbered test tubes:

• a) potassium phosphate and potassium carbonate;
• b) sodium silicate and sodium sulfate.

Let's work through the task — how to distinguish the solutions using qualitative reactions.

a) Potassium phosphate (K₃PO₄) and potassium carbonate (K₂CO₃)

1. Reaction with an acid (for example, HCl)

Potassium carbonate:

$K_{2}C{O}_3+2HCl\to 2KCl+H_{2}O+C{O}_2\uparrow$

Sign: gas is released (CO₂ bubbles)

Potassium phosphate:

$K_{3}P{O}_4+HCl\to \text{no gas released}$

Sign: no gas

Conclusion:

• Bubbles present → carbonate

• No bubbles → phosphate

2. Additional reaction (with AgNO₃)

Phosphate:

$K_{3}P{O}_4+3AgN{O}_3\to A{g}_{3}P{O}_4\downarrow +3KN{O}_3$ ​

Yellow precipitate

Carbonate:

$K_{2}C{O}_3+2AgN{O}_3\to A{g}_{2}C{O}_3\downarrow +2KN{O}_3$ ​

Light yellow precipitate (less stable)

b) Sodium silicate (Na₂SiO₃) and sodium sulfate (Na₂SO₄)

1. Reaction with an acid (HCl)

Sodium silicate:

$N{a}_{2}Si{O}_3+2HCl\to H_{2}Si{O}_3\downarrow +2NaCl$Na2​SiO3​+2HCl→H2​SiO3​↓+2NaCl

Sign: a jelly-like (gel-like) precipitate of silicic acid forms

Sodium sulfate:

$N{a}_{2}S{O}_4+HCl\to \text{no precipitate}$Na2​SO4​+HCl→no precipitate

Sign: no changes

Conclusion:

• Gel present → silicate

• No changes → sulfate

2. Confirmation (reaction with BaCl₂)

Sulfate:

$N{a}_{2}S{O}_4+BaC{l}_2\to BaS{O}_4\downarrow +2NaCl$

White insoluble precipitate

Silicate:

$N{a}_{2}Si{O}_3+BaC{l}_2\to BaSi{O}_3\downarrow$

White precipitate (but dissolves in acid)

Summary

Task 4. Experimentally determine which test tube contains each of the mineral fertilizers:

• a) calcium nitrate, ammonium sulfate;
• b) potassium chloride, potash.

Calculate and compare the nutritional value of the given fertilizers.

When compiling the lab report, present the equations of the reactions occurring in the solutions in both molecular and ionic forms.

Solution

Here is how the substances in the test tubes can be identified experimentally

a) Calcium nitrate and ammonium sulfate

Test for the ammonium ion (NH₄⁺)

Add alkali (for example, NaOH) and heat gently:

Sign:

• a pungent smell of ammonia appears → this is ammonium sulfate

Reaction:

$(N{H}_4{)}_{2}S{O}_4+2NaOH\to 2N{H}_3\uparrow +N{a}_{2}S{O}_4+2H_{2}O$

The gas can be checked with moist red litmus paper — it turns blue.

Identifying calcium nitrate

If there is no smell of ammonia, then it is calcium nitrate (Ca(NO₃)₂).

This can additionally be confirmed:

Add a solution of sodium carbonate (Na₂CO₃):

Sign:

• a white precipitate of calcium carbonate

$Ca(N{O}_3{)}_2+N{a}_{2}C{O}_3\to CaC{O}_3\downarrow +2NaN{O}_3$​

b) Potassium chloride and potash

(potash = K₂CO₃)

Test for carbonate (CO₃²⁻)

Add an acid (for example, HCl):

Sign:

• gas (CO₂) is released, hissing occurs → this is potash

$K_{2}C{O}_3+2HCl\to 2KCl+H_{2}O+C{O}_2\uparrow$

CO₂ can be confirmed:

• pass it through limewater → it will turn cloudy

Identifying potassium chloride

If there is no gas, then it is potassium chloride (KCl).

This can additionally be checked:

Add a solution of silver nitrate (AgNO₃):

Sign:

• a white precipitate of AgCl

$KCl+AgN{O}_3\to AgCl\downarrow +KN{O}_3$​

Brief table

Summary:

• ammonium sulfate → by the smell of ammonia

• calcium nitrate → by the CaCO₃ precipitate

• potash → by the evolution of CO₂

• potassium chloride → by the AgCl precipitate

1. Nutritional value of fertilizers

Nutritional value is determined by the content of the main elements: N (nitrogen), K (potassium), Ca (calcium).

a) Calcium nitrate — Ca(NO₃)₂

Molar mass:

• Ca = 40

• N₂ = 28

• O₆ = 96
  M = 164 g/mol

Nitrogen:

$\frac{28}{164}\cdot 100\%\approx 17\%$16428​⋅100%≈17%

Contains ~17% nitrogen + calcium (Ca)
A very valuable fertilizer (growth + strengthening of plants)

b) Ammonium sulfate — (NH₄)₂SO₄

Molar mass:

• N₂ = 28

• H₈ = 8

• S = 32

• O₄ = 64
  M = 132 g/mol

Nitrogen:

$\frac{28}{132}\cdot 100\%\approx 21\%$13228​⋅100%≈21%

Contains ~21% nitrogen + sulfur (S)
Richer in nitrogen

c) Potassium chloride — KCl

Molar mass:

• K = 39

• Cl = 35.5
  M ≈ 74.5 g/mol

Potassium:

$\frac{39}{74.5}\cdot 100\%\approx 52\%$74.539​⋅100%≈52%

~52% potassium
A very concentrated potassium fertilizer

d) Potash — K₂CO₃

Molar mass:

• K₂ = 78

• C = 12

• O₃ = 48
  M = 138 g/mol

Potassium:

$\frac{78}{138}\cdot 100\%\approx 56\%$13878​⋅100%≈56%

~56% potassium
Slightly richer in potassium than KCl

Comparison

Conclusion:

• by nitrogen: ammonium sulfate > calcium nitrate

• by potassium: potash > potassium chloride

2. Reaction equations in molecular and ionic form

1. Ammonium sulfate + NaOH

Molecular:

$(N{H}_4{)}_{2}S{O}_4+2NaOH\to 2N{H}_3\uparrow +N{a}_{2}S{O}_4+2H_{2}O$

Full ionic:

$2N{H}_4^{+}+S{O}_4^{2-}+2N{a}^{+}+2O{H}^{-}\to 2N{H}_3+2H_{2}O+2N{a}^{+}+S{O}_4^{2-}$ ​

Net ionic:

$N{H}_4^{+}+O{H}^{-}\to N{H}_3\uparrow +H_{2}O$

2. Calcium nitrate + Na₂CO₃

Molecular:

$Ca(N{O}_3{)}_2+N{a}_{2}C{O}_3\to CaC{O}_3\downarrow +2NaN{O}_3$ ​

Full ionic:

$C{a}^{2+}+2N{O}_3^{-}+2N{a}^{+}+C{O}_3^{2-}\to CaC{O}_3\downarrow +2N{a}^{+}+2N{O}_3^{-}$ ​

Net ionic:

$C{a}^{2+}+C{O}_3^{2-}\to CaC{O}_3\downarrow$

3. Potash + HCl

Molecular:

$K_{2}C{O}_3+2HCl\to 2KCl+H_{2}O+C{O}_2\uparrow$

Full ionic:

$2K^{+}+C{O}_3^{2-}+2H^{+}+2C{l}^{-}\to 2K^{+}+2C{l}^{-}+H_{2}O+C{O}_2$ ​

Net ionic:

$C{O}_3^{2-}+2H^{+}\to H_{2}O+C{O}_2\uparrow$

4. Potassium chloride + AgNO₃

Molecular:

$KCl+AgN{O}_3\to AgCl\downarrow +KN{O}_3$ ​

Full ionic:

$K^{+}+C{l}^{-}+A{g}^{+}+N{O}_3^{-}\to AgCl\downarrow +K^{+}+N{O}_3^{-}$ ​

Net ionic:

$A{g}^{+}+C{l}^{-}\to AgCl\downarrow$

Conclusions of the work

• nutritional value calculated
• comparison performed
• reactions written in three forms

See also

• [[b13083]]
• [[b13084]]