How many grams of MgCl2 will be produced is 20.00g Mg is reacted with an excess of Cl2

In any atom of any element, you will find protons and neutrons in the nucleus of any atom 

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Heat capacity = mcδtheat capacity = 2.676×10^3 j ..the heat capacity given is for 7.00 g of kcn,potassium cyanide which is equal to 0. mole of mole = mass  ÷ mr of kcn is 7  ÷ 65 =0.therefore: 0. of kcn liberates 2.676×10^3 j of heat1 mole   (2.676×10^3    ÷  0.107 )  × 1 =do the calculation to obtain 25009 j = 25kj