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Chemistry Calcium
Table of Contents
Calcium, Ca
Calcium, Table of Elements
Calcium experiments: 3.71.2
Calcium, properties: 3.71.3
Calcium compounds: 3.71.4
Calcium deficiency: 1.2.0 (Agriculture)
Calcium deficiency symptoms: 1.3.4 (Agriculture)
Calcium in cow's milk: 16.2.1
Calcium toxicity: 3.6.4

3.71.2 Calcium experiments
See: Calcium, (Commercial)
Chalk (lime) content of the soil: 6.43
Group 5 tests for Ba2+, Ca2+, Sr2+:
Heat calcium metal to form calcium oxide: 8.2.14
Reactions of calcium and calcium compounds: 12.4.1
Tests for calcium:
Tests for calcium (flame test):
Weight of calcium in marble: 17.6.3

3.71.3 Calcium properties
Calcium Elements, Compounds, (Commercial)
Calcium Water testing, (Scientrific)
Calcium, Ca (Latin calx lime), alkaline earth metal, calcium ion Ca2+, in many natural compounds and living organisms, burns with
brilliant light, fifth most abundant element
Calcium, metal, granulated, granules, shot, pieces, AAS Solution, Toxic if ingested or by skin contact
Decalcifying Solution is used for the decalcification microscopy sections and bone marrow core specimens is an alkaline earth metal,
granules in liquid paraffin.
Reacts with dilute HCl or H2SO4 to form H2 and metal ion, occurs mainly as carbonates, e.g. calcium carbonate, CaCO3, gypsum,
CaSO4.2H2O, 3.5% of the earth's crust, essential nutrient element for bones, teeth and muscle contraction in animals and middle lamella
of plant cells, extracted by electrolysis of fused calcium chloride.
Calcium reacts with concentrated oxidizing acids, HNO3 or H2SO4 to produce high oxidation number ions, and sulfur dioxide, SO2,
or nitrogen dioxide, NO2.
Reacts with cold water and reacts with air to form peroxides.
Calcium is the most abundant mineral, and the fifth most abundant element mostly in bone tissue.
About 1% is used in nerve transmission, muscle contraction and other functions
Atomic number: 20, Relative atomic mass: 40.08, r.d. 1.54 g cm-3| m.p. = 850oC, b.p. = 1487oC.
Specific heat capacity: 653 J kg-1 K-1
12.4.1 Reactions of calcium and calcium compounds
1. Heat a flake of calcium on wire gauze with a Bunsen burner flame.
The calcium burns brilliantly with a red flame and leaves a white residue of calcium oxide.
Add drops of water to the calcium oxide in a test-tube and note the vigorous exothermic reaction.
Test the solution with red litmus paper that turns blue.
Note that calcium oxide is not very soluble in water.
2Ca + O2 --> 2CaO
CaO + H2O --> Ca(OH)2 (s).

1.1 Drop a small piece of calcium (not old stock calcium) into a test-tube a quarter full of dilute hydrochloric acid.
Press your thumb over the mouth of the test-tube and when you can feel the pressure on your thumb test the gas for hydrogen with a
lighted splint.
Repeat the experiment with a small piece of magnesium ribbon.
The same reaction occurs, but the calcium is obviously more reactive because it slower down group 2 of the periodic table.
Usually, the lower an element in the same group of the periodic table, the more reactive it is.
Ca + 2HCl --> CaCl2 + H2
Mg + 2HCl --> MgCl2 + H2.

2. Add ammonium carbonate solution to calcium chloride solution.
Note the white precipitate of calcium carbonate.
Ca2+ + CO32- --> CaCO3 (s.)

3. Add ammonium oxalate solution to calcium chloride solution.
Note the white precipitate of calcium oxalate that is soluble in dilute hydrochloric acid but insoluble in acetic acid.
+ C2O42- --> CaC2O4 (s).

4. Add solutions of calcium salts to potassium chromate solution and to calcium sulfate solution.
No precipitate forms with calcium sulfate solution and barium salts with potassium chromate solution.

5. Add sodium phosphate solution to calcium chloride solution.
Note the white precipitate of calcium phosphate that is soluble in dilute hydrochloric acid, nitric acid or acetic acid.
3Ca + 2PO43- --> Ca3(PO4)2 (s).

6. Add concentrated hydrochloric acid to dry calcium chloride and do the flame test.
Note the brick-red flame and observe the green colour when seen through blue glass.

3.71.4 Calcium compounds
Calcium compounds, calcareous minerals, calcareous clay, marl, calcareous rock
Actinolite, Ca2(Mg, Fe2+)5(Si8, O22)(OH, F)2, (Geology)
Anhydrite, calcium sulfate anhydrous, CaSO4, "snake alabaster"
Apatite, Ca5[F (PO4)3]: (Geology)
Aragonite, CaCO3, calcium carbonate (pea stone in hot springs), Dimorphism (Geology)
Bustamite, MnCaSiO6, manganese silicate: (Geology)
Dolomite, CaMg(CO3)2: 35.19.1 (Geology)
Calcium acetate H2O, CaC4H6O4, calcium acetate monohydrate, calcium diacetate
Calcium acetate, Metallic salts gels:
Calcium bromide, CaBr2
Calcium carbide, CaC2
Calcium carbonate
Calcium chlorate (I) (in bleaching powder with calcium hypochlorite)
Calcium chloride
Calcium chromate, CaCrO4, yellow powder, slightly soluble in water.
Calcium citrate (tribasic tetrahydrate)
Calcium copper silicate, CaCuSi4O10, cuprorivaite, Egyptian blue, caeruleum, ancient pigment
Calcium cyanamide, CaCN2, nitrogen fertilizer
Calcium dicarbide, CaC2, calcium carbide, calcium acetylide, carbide
Calcium dihydrogen phosphate V, Ca(H2PO4)2, monohydrate Ca(H2PO4)2, Harmful if ingested in excess
Calcium fluoride, calcium fluorite, fluospar, Harmful if ingested
Calcium fluorophosphate dihydrate, CaFO3P.2H2O
Calcium hydride, CaH2
Calcium hydrogen carbonate, calcium bicarbonate
Calcium hydrogen phosphate, calcium hydrogen orthophosphate (dihydrate), dicalcium phosphate, Harmful
Calcium hydroxide, Ca(OH)2, slaked lime
Calcium hydroxyapatite, dental enamel, Ca5(PO4)3(OH), Ca10(PO4)6(OH)2: 9.226
Calcium hypochlorite
Calcium hypophosphite, H4CaO4P2
Calcium hyroxyapatite, calcium hydroxyl apatite, Ca10(PO4)6(OH)2, Teeth and toothpaste: 9.226
Calcium iodate, CaI2O6
Calcium iodide, CaI2
Calcium lactate, C6H10CaO6, baking powder E327, calcium lactate 5-hydrate, in cheese, prevent tooth decay
Calcium magnesium acetate (CMA), De-icers, ice melts:
Calcium magnesium carbonate, dolomite CaMg(CO3)2: 35.19.1 (Geology)
Calcium magnesium carbonate, CaCO3MgCO3, dolomite, [but "dolomite" is any high Mg:Ca carbonate rock]
Calcium malonate in beetroot
Calcium manganese silicate, bustamite, MnCaSiO6: (Geology)
Calcium metaborate, B2CaO4.2H2O
Calcium nitrate, Ca(NO3)2
Calcium nitrite, CaN2O4
Calcium octadecanate, calcium stearate, Ca[CH3(CH2)16COO]2, hard water scum on bath tubs
Calcium orthophosphate, Harmful if ingested
Calcium oxalate, CaC2O4
Calcium oxide, CaO, quicklime
Calcium perchlorate, CaCl2O8
Calcium phosphate
Calcium phosphide, active phoshor, Ca3P2, in incendiary bombs, rat poison "Photophor"
Calcium phosphide, solid, Toxic if ingested or by skin contact
Calcium phosphide, Solution < 0.1% Not hazardous
Calcium plumbate, formerly in lead-based priming paint, lead poisoning if children eat old paint scales
Calcium polysulfide, lime sulfur, CaSx (CaOH + S), agricultural fungicide: 16.6.12
Calcium propionate (CH3CH2COO)2Ca, food additive E282, preservative, anti-fungal mould inhibitor
Calcium pyrophosphate, Ca2O7P2
Calcium silicate, calc-flints, Wollastonite mineral, Ca3(Si3O9), table spar
Calcium silicate, CaSiO2
Calcium silicide technical, CaSi2
Calcium stearate, Ca(CH3(CH2)16COO)2, calcium octadecanoate, bath scum
Calcium sulfate, CaSO4, gypsum
Calcium sulfite, food additive, preservative, firming agent E226
Calcium tetrahydrogen phosphate (V), calcium hydrogen orthophosphate, secondary calcium phosphate
Calcium tetrahydrogen diorthophosphate
Calcium thioglycollate
Calcium trifluoromethanesulfonate, C2CaF6O6S2
Calcium tungstate, CaWO4 (in cathode ray tubes), scheelite: 35.20.38 (Geology)
Calcite, Calcium carbonate
Carving stones, Limestone, stone dust and carving stones: 35.22.7 (Geology)
Dolomite, CaMg(CO3)2: 35.19.1 (Geology)
Drierite drying agent, with moisture indicator, CaO4S
Fluorite, fluorspar, fluoride, CaF2, (Geology)
Gypsum, calcium sulfate, plaster of Paris, CaSO4.2H2O (Geology)
Hornblende: 35.17.0 (Geology)
Lime sulfur, CaSx: 16.6.12, (Fungicide, acaracide and insecticide) (Agriculture)
Marble, CaCO3: 35.23.3, (Geology)
Montmorillonite (smectite), Fuller's earth, bentonite: (Geology)
"Plasticine", modelling clay
Scheelite crystals, calcium tungstate, CaWO4: 35.20.38 (Geology)
Tanzanite, Ca2(Al3)(Si2O7)(SiO4)O(OH): 35.20.52 (Geology).

Calcium carbide
Calcium carbide, CaC2, calcium dicarbide, calcium acetylide, carbide, acetylenogen, ethnide dicarbide, Toxic by all routes.
Calcium carbide, called "carbide", acetylenogen, was used in carbide lamps in cave explorer lamps, formerly in bicycle headlamps and
underground mines.
Many fires and explosions resulted from these lamps and they are now rarely used.
The main hazard with calcium carbide is the ignition of air / acetylene mixtures.
A violent explosion may occur, depending on the proportions of air and acetylene.
Acetylene, when undiluted with air, burns with a smoky flame.
Before igniting acetylene, be sure that it is NOT mixed with air.
Calcium carbide usually contains sulfur and phosphorus compounds that react with water to form strongly smelling gaseous
impurities that act as a convenient indicator for the presence of acetylene.

Calcium carbonate, CaCO3
See: Models (Scientrific), Models inorganic, Calcium carbonate, (Commercial)
Calcium carbonate, CaCO3, marble chips, precipitated, aragonite, carbonate of lime, [calcite, Iceland spar]
Calcium carbonate, limestone (pea stone in hot springs), chalk (lime), with HCl forms CO2
Aragonite, CaCO3, calcium carbonate (pea stone in hot springs), Dimorphism
Calcite, CaCO3, Calc-spar, Iceland spar: 35.19.0
Calcite crystals, Birefringence: 27.181
Calcium carbonate gel, Metallic salts gels:
Calcium carbonate, limestone, calcarenite, marble, hard water calcination deposit, tennis court marking lime
Calcium carbonate dissolves in rain water:
Carbon dioxide through calcium carbonate suspension: 12.16.1
Chalk: 35.22.3
Chalk (lime) content of the soil (Agriculture): 6.43
Dilute hydrochloric acid with calcium carbonate:
Dilute hydrochloric acid with marble chips, Particle size: 17.2.1
Dilute hydrochloric acid with marble chips (balloons to collect gases): 17.1.4
Dilute hydrochloric acid with marble chips, gas burette: 17.1.3
Langelier saturation index: 18.7.43, (swimming pools)
Lime, CaO
Lime, lime water, limestone
Low cost: whiting, from pottery supplies stores, some antacid powders, building stores for crushed marble
Marble, marble chips, 4-6 mm, 9-12 mm: 35.23.3
Plasticine, modelling clay
Putty: 3.68
Tests for limestone: 35.31 (Geology)
Tests for carbohydrates, Molisch's test (α-naphthol test): 9.134
Tests for carbonates:
Weight of calcium in marble, calcium carbonate: 17.6.3.

Calcium carbonate, CaCO3, powder, almost insoluble in water unless dissolved CO2 present, calcite, chalk, limestone, Iceland spar,
marble chips, marble whiting, whiting, chalk, calc-spar, pearl, coral, egg shells, whitewash, calcimine, seashells (in antacid medicines
to suppress reflux), Vienna lime, E170 firming agent food additive, heated in a lime kiln to form lime CaO, powdered abalone or oyster
shell used as folk medicine (school chalk, but usually school chalk is calcium sulfate).
"Plasticine", modelling clay, is said to contain calcium carbonate, stearic acid, petroleum jelly, whiting, ten pigments, formerly "Harbutt's
plasticine", "Plastilina" is a similar product.
Common names: chunks: marble, limestone, powder: precipitated chalk.

Calcium chloride, CaCl2
Calcium chloride anhydrous, granular, CaCl2
Calcium chloride dihydrate, CaCl2.2H2O
Calcium chloride, fused, dried calcium chloride (1.5-2.5 mm)
Calcium chloride hexahydrate, CaCl2.6H2O
Calcium chloride monohydrate, CaCl2.H2O
Calcium chloride, anhydrous, CaCl2, 0.l M solution, 11 g in 1 L water
Calcium chloride, CaCl2.2H2O, For 0.1 M solution, 14.7 g in 1 L water
De-icers, ice melts:
Low cost: ice melt products, from brewing / wine making supply stores, garden stores as trace nutrient fertilizers
Low cost, prepare : calcium carbonate with muriatic acid
Soft water, low calcium content, cause etching of swimming pool surfaces, increase with calcium chloride.

Calcium chloride, anhydrous, granular, CaCl2, white granules or lumps, very hygroscopic, m.p. 772oC (drying agent, desiccant), E509,
used to form calcium metal, sold as laundry booster, de-icing chemical, Harmful if ingested.
Calcium chloride dihydrate, CaCl2.2H2O.
Common names: Laundry aid, laundry salt, road salt (de-icing agent but must be pure calcium chloride).

Calcium dihydrogen phosphate
Calcium dihydrogenphosphate, Ca(H2PO4)2.H2O, calcium phosphate monobasic, calcium dihydrogenphosphate monohydrate,
calcium dihydrogen phosphate (V), calcium tetrahydrogen di-orthophosphate, calcium dihydrogen phosphate, leavening agent in baking

Calcium fluoride, CaF2
See: Models (Scientrific), Models inorganic, Calcium fluoride, (Commercial)
Calcium fluoride, CaF2, fluorite, fluorspar, Blue John, white crystalline solid, thermoluminescent, for craft, fluoridated tooth paste,
source of hydrofluoric acid and fluorine, in opal glass
Calcium fluoride, fluorspar, fluorite, blue john, Derbyshire spar, fluorspar, CaF2: 35.20.14 (Geology)
Prepare hydrogen fluoride, HF:

Calcium hydrogen carbonate, Ca(HCO3)2
Calcium hydrogen carbonate, calcium bicarbonate, Ca(HCO3)2, temporary water hardness, stable in solution
Calcium hydrogen carbonate, Temporary (water) hardness and permanent hardness:
Dilute acids with calcium hydrogen carbonate:

Calcium hydroxide, Ca(OH)2, slaked lime
Calcium hydroxide, Ca(OH)2, 0.02 M, saturated solution, 1.5 g Ca(OH)2 per litre.
Common names: slaked lime, garden lime, caustic lime
Calcium hydroxide, Ca(OH)2, slightly soluble powder, solution called "lime water", 10 g in 1 L of water, shake, allow it to settle, then
decant the clear liquid.
Calcium hydroxide (whitewash, milk of lime, garden lime), E526.
Calcium hydroxide solution, calcium hydroxide powder (lime water, lime), slaked lime, Harmful if ingested
Carbon dioxide with calcium hydroxide solution:
Low cost, from garden supply stores, as hydrated lime, slaked lime, lime, may also contain CaO or CaCO3
Lime (quicklime and slaked lime): 34.3.1
Prepare quicklime by slaking: 34.3.3
Prepare lime water, ionization of calcium hydroxide: 5.3.5
Prepare ammonia gas: 3.33.0.

Calcium hydroxide, Ca(OH)2, 0.02 M, saturated solution, 1.5 g Ca(OH)2 per litre.
Calcium hydroxide solution, lime water, 10 g in 1 L of water, shake, allow it to settle, then decant the clear liquid.
Common names: slaked lime, garden lime.

Calcium hypochlorite, Ca(OCl)2
Calcium hypochlorite:
Calcium hypochlorite, hydrated, bleaching powder, chlorinated lime, Toxic by all routes
Calcium hypochlorite, Solution < 5%, Not hazardous
Calcium hypochlorite dry, for swimming pools, "dry pool chlorine", Toxic by all routes
Prepare trichloromethane (chloroform): 16.1.14.

Calcium hypochlorite, Ca(OCl)2, bleaching powder (technical grade: available chlorine, 65%), bleaching agent, chlorinated lime,
chloride of lime, calcium oxychloride grey-white powder, irritating odour, exothermic when dissolved in water, may explode if NOT
stored securely (bleaching powder contains both calcium hypochlorite, [calcium chlorate (I), chlorinated lime] and calcium hydroxide,
water sanitizing, whitening agent, "solid chlorine" is 70% chlorine for swimming pools).
Bleaching powder forms chlorine gas that is highly irritant to the lungs.
If acid is added to bleaching powder, large amounts of chlorine are produced.
The mixture becomes hot and may boil violently.
Do not add concentrated ammonia to bleaching powder because nitrogen trichloride, because NCl3, may form.
This is a violently unstable liquid, liable to explode without apparent reason.
Bleaching powder is a convenient source of chlorine gas for other experiments.
Add dilute hydrochloric acid from a dropping funnel to a slurry of bleaching powder and water, in a conical flask fitted with a rubber
stopper and gas collection system.
Keep a solution of sodium hydroxide nearby to stop the reaction.
Adding sodium hydroxide solution to the mixture does not pose any problems.
Dispose of the waste mixture by diluting it with water and washing it down the drain.

Calcium nitrate, Ca(NO3)2
Calcium nitrate, Ca(NO3)2.4H2O, calcium nitrate (V)-4-water, crystals
Calcium nitrate tetrahydydrate, Ca(NO3)2.4H2O, calcium nitrate (V)-4-water
Calcium nitrate tetrahydrate, CaN2O6.4H2O
Calcium nitrate hydrated crystals
Calcium nitrate, Norwegian saltpetre, nitrogen fertilizer
Calcium nitrate, Ca(NO3)2, For 0.1 M solution, 16.4 g in 1 L water, Harmful if ingested.

Calcium oxalate, CaC2O4, Ca(COO)2, oxalate of lime, needle-shaped crystals, in kidney stones, rhubarb
Raphides, needle-shaped crystals of calcium oxalate monohydrate, usually in mesphyll parenchyma of leaves.

Calcium oxide, CaO, quicklime
Calcium oxide, quicklime, lump, powder, does not occur naturally, Toxic if ingested or by skin contact
Decomposition of oxides: 3.30.5
Heat calcium metal to form calcium oxide: 8.2.14
Lime, lime water, limestone.

CaO, calcium oxide, lime, quicklime, lump lime, caustic lime, burnt lime, E529, thermoluminescent in oxy-hydrogen flame to cause
"limelight", used in agriculture for excess soil acidity, sold in building supplies shops, Toxic if ingested or by skin contact.
Calcium oxide does not occur naturally.

Calcium phosphate, Ca3(PO4)2
Calcium dihydrogen phosphate (V), Ca(H2PO4)2, monohydrate Ca(H2PO4)2.H2O
Calcium phosphate (V), monocalcium phosphate Ca(H2PO4)2, dicalcium phosphate CaHPO4
Calcium phosphate (V), tricalcium phosphate Ca3(PO4)2, (hydroxyapatite, bone mineral, tooth enamel)
Bone, calcium hydroxyapatite, Ca10(PO4)6(OH)2, + other ions
Calcium hydroxyapatite, Ca5[OH (PO4)3], Ca10(PO4)6(OH)2, similar to bones so bioactive used in surgical implants
Calcium phosphate, calcium phosphate (V) (dibasic), Ca3(PO4)2, Harmful if ingested
Apatite Ca3(PO4)3(OH, F, Cl)
Calcium phosphate (formerly calcium orthophosphate)
Prepare baking powder, chemical leavening agent, sponging agent: 19.1.9
Calcium phosphate dibasic, HCaO4P
Calcium phosphate tribasic, HCa5O13P3
Calcium phosphate monobasic, monohydrate, H4CaO8P2.H2O
Calcium phosphid, active phoshor, Ca3P2
Calcium pyrophosphate, Ca2O7P2.

Calcium phosphate, Ca3O8P2
Ca3(PO4)2, β-calcium phosphate tribasic, β-tricalcium phosphate, tert-calcium phosphate,
tri-calcium (ortho)phosphate, calcium phosphate (V), white powder, insoluble, from apatite mineral Ca5(PO4)3(OH, F, Cl), and rock
phosphate, from animal bones and teeth (used for fertilizer, facilitates uptake of DNA into cells, "bone ash" for craft), E341 Calcium
phosphates (buffer, sequestrant), formerly "calcium orthophosphate".
Calcium phosphate (V), monocalcium phosphate Ca(H2PO4)2, dicalcium phosphate CaHPO4, tricalcium phosphate Ca3(PO4)2,
(hydroxyapatite, bone mineral, tooth enamel)
Calcium phosphate stones, CaHPO.4.2H2O, brushite, a kind of human kidney stone.

Calcium sulfate, CaSO4, gypsum
Calcium sulfate, calcium sulfate (VI), Harmful if ingested
Gypsum (calcium sulfate), plaster of Paris: 35.22.6
Tests for gypsum added to the soil: 6.15.5
Plaster of Paris
School chalk, blackboard chalk, safety: 3.71.5
School chalk, blackboard chalk with weak acids: 3.71.7
Solubility of school chalk, blackboard chalk, in water: 3.71.6.

Calcium sulfate, CaSO4, gypsum, CaSO4.2H2O, powder, calcium sulfate dihydrate, calcium sulfate (VI), calcium hemihydrate,
anhydrite mineral
Calcium sulfate anhydrous, CaSO4, anhydrite mineral, alabaster statues, "snake alabaster" in ore veins
Calcium sulfate, dihydrate, CaSO4.2H2O, gypsum, plaster of Paris, plaster, casting plaster (modroc), grout
Calcium sulfate, hydrated, CaSO4.2H2O, selenite, satin spar, anhydrite, school chalk, blackboard chalk
Calcium sulfate, hydrated, For 0.1 M solution, shake 10 g in 1 L water, leave to stand, decant the clear liquid
Calcium sulfate, hemihydrate, CaSO4.H2O, hemihydrate, plaster of Paris
Calcium sulfate, CaSO4, gypsum, CaSO4.2H2O, powder, calcium sulfate dihydrate, calcium sulfate (VI), calcium hemihydrate,
anhydrite mineral.
Calcium sulfate occurs as plaster of Paris, CaSO4.H2O, potters' plaster, school chalk, blackboard chalk, selenite, craft modelling
powder, E516, which can be shaped before setting.
Calcium sulfate occurs in evaporating lakes.
Calcium sulfate is used as a stain remover and has anti-inflammatory action in the human body.
Alabaster, The term "alabaster" may refer to gypsum, or calcite, called "onyx-marble".
Anhydrite, calcium sulfate anhydrous, CaSO4, "snake alabaster", mineral
Gypsum and bentonite mixtures provide low electrical resistance around anodes and earthing rods.
Common names: Plaster of Paris CaSO4.H2O.
(The term "alabaster" may refer to gypsum, or calcite, called "onyx-marble".)
Mixtures of gypsum and bentonite provide low electrical resistance around anodes and earthing rods.

Acids and metal carbonates, insoluble carbonates, prepare salts: 2.4
Carbonates, CO32-, mineral carbonates: 35.19.2
Decomposition of carbonates: 3.30.1
Dilute acids with carbonates, common carbonates:
Heat carbonates of Cu, Mg, Na, Pb, Zn: 12.16.3
List of carbonates: 1.11
Prepare carbon dioxide, heat carbonates: 13.7.6
Prepare rayon, basic copper carbonate with ammonia solution:
Reactions of carbonates: 12.16.0
Tests for carbonates:

Chalk, CaCO3
Chalk, calcium carbonate, rock chalk, French chalk, talcum powder
Blackboard chalk, school chalk, is mainly calcium sulfate
Blackboard chalk used for chromatography
Chalk (lime) content of the soil, 6.43
Chalk, breccia, sedimentary rock, 35.22.3
Cloud in a bottle: 37.29
Portland cement: 3.66.6
School chalk, blackboard chalk, safety: 3.71.5
School chalk, blackboard chalk with weak acids: 3.71.7
Solubility of school chalk, blackboard chalk, in water 3.71.6.

3.71.5 School chalk, blackboard chalk, safety
The chemicals in blackboard chalk, mainly gypsum, CaSO4.2H2O, are harmless if ingested.
However, chalk dust may cause respiratory problems in children with asthma, and in teachers after exposure for many years.
The new product called "dustless chalk" is chemically the same but the chalk dust it produces consists of much heavier particles that
quickly drop down instead of being suspended in the air.
Chalk dust should be regularly cleaned out of the classroom .
Chalk dust may damage electronic equipment, e.g. computer motherboard and playback heads of VCRs.
Yellow chalk on a green "blackboard" may be more visible to most students but may cause problems for colour-blind students.

3.71.6 Solubility of school chalk, blackboard chalk, in water
Shake powdered blackboard chalk (school chalk), mainly gypsum, CaSO4.2H2O, with water in a test-tube.
Filter the mixture and collect the filtrate in an evaporating basin.
Evaporate the water by heating the evaporating basin over a beaker of boiling water.
Examine the inside surface of the basin.
If any residue is found, then some chalk is soluble in water.

3.71.7 School chalk, blackboard chalk with weak acids
Put three sticks of blackboard chalk, mainly gypsum, CaSO4.2H2O, in beakers partly filled with water, lemon juice, vinegar, so that
about half of each stick is still dry.
Observe the chalk sticks over the next days.
The chalk sticks dissolve in the weak acids.

Cement Ice melts, de-icers
35.25 Make sedimentary rocks
35.24.2 Make artificial rocks, sedimentary rocks Pozzolana (puteolanum) Roman Maritime Concrete Study (ROMACONS) Scoria
34.6.3 Strength of paper, shape and its mechanical strength
3.66.3 Tests for concrete alkalinity
3.66.1 Tests for cement brick strength, (contents).

Materials used with concrete
Carving stones include the following: Hebel blocks are autoclaved aerated concrete
Muriatic acid, hydrochloric acid, in hardware shops, about 30% for cleaning or etching concrete.
Muriatic acid (25% solution) (in concrete bleach
Titanium dioxide, TiO2, brookite mineral, in self-cleaning concrete
Phosphoric acid for cleaning concrete,
Volatile oils: Plant material --> (solvent extraction) --> "concretes" --> "absolutes".
Exothermic reactions, the reactants form products with rise in temperature, Setting of cement and concrete
Metallic corrosion requires at least one metal and an electrolyte, water, soil, concrete or a moist atmosphere.
A metal in an electrolyte (water, sea water, soils, concrete) generates an electrical current depending on the type of electrolyte.