Chemistry Report 4

UNIVERSITI PENDIDIKAN SULTAN IDRIS TKU 1013 BASIC CHEMISTRY I LAB REPORT: HYDRATED SALT FORMULA (EXPERIMENT 4)

TUTOR’S NAME: PN. FARIDAH BINTI YUSOF

NAME : NOR HASMALINA BINTI HASSAN MATRIC NO. : D20081032321 SEMESTER : 3

OBJECTIVE

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1. To determine the volume of water content in hydrated salt. 2. To determine the formula of hydrated salt.

RESULT

Mass CuSO4 (Copper (II) Sulfate) before heat

2.013 g

After heat (mass crucible + cover)

56.640 g

After heat (mass crucible + cover) + CuSO4

58.650 g

After heat (mass crucible + CuSO4 + cover) – first reading

57.930 g

After heat (mass crucible + CuSO4 + cover) – second reading

57.910 g

After heat (mass crucible + CuSO4 + cover) – third reading

57.910 g

After heat, salt will added with few drop of water = producing blue colour. Temperature before adding a few drop of water = 27⁰C Temperature after adding a few drop of water = 49⁰C

CALCULATION

compound

Water, H2O

Copper (II) sulfate), CuSO 4



Number of mole

0 .7 4

Ratio number of mole

Number of ratio

(2+16)

(63.55 + 32.07 + 64 )

=0.74

=1.27

18

159.62

=0.041

=0.008

0.041

0.008

0.008

0.008

=5

=1

5

This calculation proof that the hydrated salt is CuSO4.5H2O

DISCUSSION

1.27

1



to absorb water vapor from the air, thus becoming hydrated compounds. On the other hand, some hydrated compounds tend to spontaneously loose their water of hydration when they are placed in a dry environment. In this experiment, the number of water molecules associated with each formula unit of a salt will be determined. determined. The amount of water in the hydrated hydrated compound will be determined determined by heating a massed sample of the the compound in order to drive off the water. From the mass change, the percent water water in the sample sample will be determined. determined. (This informat information ion can be used to calculate calculate the formula of the compound). Some compounds have water molecules molecules in their structure when they form a solid. These substances are called hydrates. hydrates. The amount of water present present is in a definite mole ratio of water to compound. The water can be removed by heating the substance. CuSO4.5H2O

CuSO4 + 5H2O

Hydrate is the chemical compound that contains water. A common hydrate is the familiar form of Copper (II) Sulfate. Chemically, it is cupric sulfate pentahydrate, CuSO4·5H2O. When a crystal of the substance is formed, five molecules of water (H 2O) are combined in the crystal with each molecule of Copper (II) Sulfate (CuSO4). This water is called water of crystallization. When When cupric cupric sulfat sulfatee pentahy pentahydra drate te is heated heated,, the water water of crysta crystall lliza izatio tion n is driven driven off and anhydrous cupric sulfate is formed. It has several properties different from the pentahydrate, e.g, color, density, and crystal structure. When When anhydro anhydrous us salt salt will will dissol dissolve ve in water, water, a blue blue soluti solution on will will be formed formed.. This This is because the formation of a crystalline structure, upon hydration give CuSO4 the blue colour. The blue blue colour colour is due to the water of crysta crystall lliza izatio tion n (CuSO (CuSO4.5H2O). When this is removed by heating, heating, basic copper sulphate sulphate is left (CuSO4.H2O) and this can be further broken to simple CuSO4. It is essential you realise the water is not there as free liquid, but as a molecule in its own right and it is bound to the copper atom. These molecules fulfill a structural role in as much as they fill voids in the crystal structure and let the salt ions take up a regular and therefore crystalline, shape of minimal energy content. In the case of all transition metals, the water of hydration is linked to the d (or higher) orbitals and these distort To get a good result, be sure to keep the lid on the crucible while cooling to prevent



red. A glowing red crucible can cause the salt to decompose and make you you percent of water too high. Always handle crucibles with crucible tongs. Hot crucible look like cold crucibles. Oil from fingers can affect the mass. Always place hot crucibles on heat resistant boards. Hot crucibles can incinerate your laboratory manual. For this experiment the process when water release from hydrated salt is exothermic process because the temperature after adding a few drop of water is higher than the temperature after adding a few drop of water. water. This process will release the energy. energy. Exothermic (outside heating) describes a process or reaction that releases energy usually in the form of heat of heat..

Chemistry Report 4

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