Making Pure Calcium Carbonate

Nan's Nook : Archives : Casings : Lime
Posted by: Fungusmaximus Feb 15 03, 04:27 PM GMT

Calcium carbonate is an abundant chemical and it is found in many different forms. Among these are limestone, a sedimentary rock formed from the shells of mollusks. Calcium carbonate is manufactured in industry by the method in this lab. It is widely used as an antacid to neutralize the hydrochloric acid produced by the stomach, and also as a source of calcium to strengthen bones. Another form of calcium carbonate is chalk. Chalk is made for use as a gentle scouring powder. For that reason, it is used in toothpaste. Chalk is easy to make. In this lab you will combine calcium chloride and sodium carbonate to make chalk. Suppose you were given known amounts of calcium chloride and sodium carbonate. How much chalk would you make?

Equipment and Supplies per Lab Station

# I beaker - 150mL, #2 beaker - 250mL, ehrlenmeyer flask, funnel, filter paper, balance, graduated cylinder, approximately 2 g. of sodium carbonate, Naª CO£ , 20 mL of 1 M solution of calcium chloride.

What to Do

1. Label two, clean beakers, respectively #1 (100 to 150 ml) and #2 (250 ml)

2. Fold a piece of filter paper to make a filter. Place it in beaker #1. Find the mass of the beaker and filter paper. Mass of beaker #1 + filter paper = _______________g

3. Set up a funnel for filtering using an Ehrlenmeyer flask. Now place the weighed filter

paper into the funnel. Dampen it slightly with water.

4. Place 20 mL of 1 M calcium chloride, CaClª , solution in beaker #1. Set it aside.

5. Place 2.5 g of sodium carbonate, Naª CO£ , into beaker #2.

6. Add 20 mL of water to beaker #2. Swirl the beaker until all of the sodium carbonate has dissolved.

7. Pour the sodium carbonate solution into the 20 mL of calcium chloride solution in beaker #1. Swirl gently to mix. To filter the solution, place a funnel in an Ehrenmeyer flask. Fold a filter paper as instructed, and place it in the funnel. Wet with water so it sticks to the sides of the funnel.

8. Pour the mixture into the filter. Add a little at a time. Each time fill the filter not more than half full. Do not spill any. Use a wash bottle to obtain the remaining mixture.

9. Continue to filter until all the liquid has drained through. Discard the clear filtrate.

10. Gently loosen the filter paper from the funnel. Place the filter paper and its contents into the beaker #1. Set the beaker and its contents aside to dry overnight.

Posted by: Fungusmaximus Feb 15 03, 04:24 PM GMT
What is Calcium Carbonate?
Calcium Carbonate is an exceptional mineral. The chemical
formula CaCO3 covers a raw material, which is widespread
throughout nature, whether dissolved in rivers and oceans,
in molten form as “cold” carbonatite-lava, or solid as a
mineral in the form of stalactites, stalagmites or as the
major constituent of whole mountain ranges. Plants and
animals need calcium carbonate to form their skeletons
and shells. In fact, when considering our lives, modern
mankind could hardly imagine existing without calcium
carbonate. Almost every product in our daily lives either
contains calcium carbonate or has some association with
the mineral during its production.
The Ear th’s crust contains more than 4% calcium
carbonate. As a result, the three calcium carbonate
minerals - calcite, aragonite and vaterite - are among the
most important rock-forming minerals. Rocks are not the
only calcium carbonate deposits in nature, most stretches
of water and countless plants and animals contain huge
amounts of calcium carbonate. The link between these
natural resources is the calcium carbonate cycle.
Plants and animals absorb calcium carbonate from water -where
it exists, in most cases, in the dissolved form of
calcium hydrogen carbonate Ca(HCO3 )2 - and use it to build
up their skeletons and shells. After their death, mussels,
coccoliths, algae and corals form sedimentary deposits on
sea-beds, thus the rock forming process is put in motion.
The first stage is the sedimentation process from which
chalk and limestone originate. Chalk is a poorly compacted
sedimentary calcium carbonate rock, whose diagenesis is
incomplete. When the sedimentation process is completed
this results in the formation of limestone. If the
sedimentation process takes place in magnesium
containing water a dolomitisation may occur. Part of the
calcium ions in the crystal lattice are replaced by
magnesium ions, a fact that leads to the formation of
dolomite CaMg[CO3 ]2 . Marble is a metamorphic rock, which
is the result of a recrystallisation process of limestone,
under conditions of high pressure and temperature. The
carbonate rocks, chalk, limestone, dolomite and marble
rocks are subject to erosion, under the influence of wind,
temperature and water they dissolve, and the cycle may
start again.
Multiple properties – manifold uses
Calcium carbonate rocks are spread throughout the world,
which is why they have been among the most widely used
raw materials for more than 5000 years. Long ago, the
Egyptians built their pyramids with limestone, and today we
still use hundred of millions of tonnes of calcium carbonate
in the building industry alone. However, although the
deposits are plentiful, only a few are of sufficiently high
quality to be worked and even a fewer number of deposits
will provide raw materials for industrial and agricultural uses
other than the construction and roads building industry.
Only if the purity, degree of whiteness, thickness and
homogeneity are acceptable is commercial extraction
worthwhile. After quarrying, further treatment is required to
process natural calcium carbonates of the highest quality,
known generically as Ground Calcium Carbonate (GCC).
Precipitated Calcium Carbonate (PCC) is a synthetic
calcium carbonate produced industrially by means of a
recarbonisation process.
Both GCC or PCC can be used in a wide range of
applications. For each end use there exists a tailor-made
product, where fineness and particle size distribution are
optimally balanced to meet the technical demands of that
particular requirement.
Industrial minerals. Yo u r world is made of themഊl Paper: Over the last 30 years, the use of calcium
carbonate has grown significantly as technology in the
paper industry has moved from acid to neutral sizing.
Today, calcium carbonate is the most widely used
mineral in paper-making. GCC and PCC are used both as
a filler and a coating pigment, and help produce papers
with high whiteness and gloss and good printing
l Plastics: Calcium carbonate is by far the most important
mineral for compounding with polymers. By weight it
accounts for more than 60% of the filler and
reinforcements market. Main applications include
plasticised and rigid PVC, unsaturated polyesters,
polypropylene and polyethylene. Other important areas
of use include rubber, foamed latex carpet-backings,
sealants and adhesives.
Calcium carbonate is not only a filler added to reduce
costs and extend petroleum based resources, many
properties of the plastic can be influenced by the use of
calcium carbonate. Breathable PE-films for hygiene
products and the building industry, for example, can only
be produced with the incorporation of a filler such as
calcium carbonate.
l Coatings: In paints and coatings, calcium carbonate has
established itself as the main extender. Fineness and
particle-size distribution can contribute to the opacity of
coatings. Moreover, calcium carbonate can offer
improvements in weather resistance, anti-corrosion and
rheological properties, coupled with low abrasiveness,
low electrolyte content, and a pH stabilising effect. In
water-based systems calcium carbonate reduces the
drying time.
l Environment: As a natural product, calcium carbonate is
perfect for environmental protection applications. For
example, flue gas desulphurisation, drinking water
treatment, waste water treatment and forest and lake
liming for the neutralisation of acid rain, are all growth
areas for the use of calcium carbonate. It has a natural
b u f f e r-effect and works as a pollution-filter. These
properties, likewise, apply to the derivative products.
l Agriculture: Calcium fertilisers were one of the first to
be widely used. The Greeks and Romans were aware of
their attributes. Their use guarantees an adequate supply
of calcium to plants and stabilises the pH-value of the
soil. These characteristics make calcium carbonate an
i m p o r tant fertiliser for the agriculture and forestry
sectors. Every year, in Europe alone, more than 4.5
million tonnes are supplied to this market. Other
agricultural-related uses of calcium carbonate include its
use as a calcium supplement in animal feed
l Others: Glass, ceramics and blackboard chalk, together
with cleaning, dental care and cosmetic products are
produced by the wide range of industrial manufacturers
who rely on calcium carbonate. As a natural mineral,
calcium carbonate has a multitude of characteristics that
make it an ideal raw material for widely differing uses.
No one calcium carbonate is exactly like another,
whichever property is needed a high grade product is
there to meet the demand. Diverse requirements such as
low iron oxide content for the production of high-quality
glasses, the authorisation for uses in foodstuffs, good
buffering-effect or low abrasion, can be met by an
existing grade of calcium carbonate.
For more information, please contact:
CCA-Europe – The European Calcium Carbonate
Association (Member of IMA-Europe)

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