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we did a lab at school lately. let Na2CO3, MgCO3, and CaCO3 reacts with HCl...

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user3498849 | (Level 2) eNoter

Posted February 20, 2013 at 2:38 AM via web

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we did a lab at school lately. let Na2CO3, MgCO3, and CaCO3 reacts with HCl individually. the result shows that  Na2CO3+HCl react the fastest while the reverse was true for MgCO3. Why is that? Why does Na2CO3 react the fastest an MgCO3 is the slowest? How do I measure the rate of the reaction just by observing? Thank you.

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted February 20, 2013 at 6:39 AM (Answer #1)

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The rate of reaction of the salts can be explained with the nature of their solubility. Among the three salts, Na2CO3 is the most soluble in water. CaCO3 and MgSO3 are sparingly soluble. Being soluble means that they form ions easily copmapred to those that are insoluble. When an acid, such that of hydrochloric acid, reacts with it, the reaction would be easier. The more ease of reaction, the higher the reaction rates. 

The reactions of the salts with HCl can be written as:

`Na_2CO_3 + 2HCl -> 2NaCl + H_2O + CO_2`

`CaCO_3 + 2HCl -> CaCl2 + H_2O + CO_2`

`MgCO_3 + 2HCl -> MgCl_2 + H_2O + CO_2`

By just observation, you can measure the rate of the reaction by measuring the time when the physical transformation is done. But be sure that each of the three salts contains equal number of moles. 

 

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