8.21 What are the guidelines for writing athermochemical equation?

1.	8.21 What are the guidelines for writing athermochemical equation?
Answer» 1)For exothermic reaction, ΔH is negative whereas for endothermic reaction, ΔH is positive. 2)ΔH values are for the standard state of the substance ( 298 K and 1 bar pressure ) 3) The coefficients of different substances represents the number of moles reacted and formed for the heat change represented in the equation. 4) The physical state of the different substances must be mentioned as the heat evolved or absorbed depends upon the physical state. 5) If the coefficient of the substances are multiplied or divided by some number , the value of ΔH is multiplied or divide by the same number. 6) If the reaction is reversed ,the sign of ΔH changes but the magnitude remains the same.

Answer»

1)For exothermic reaction, ΔH is negative whereas for endothermic reaction, ΔH is positive.

2)ΔH values are for the standard state of the substance ( 298 K and 1 bar pressure )

3) The coefficients of different substances represents the number of moles reacted and formed for the heat change represented in the equation.

4) The physical state of the different substances must be mentioned as the heat evolved or absorbed depends upon the physical state.

5) If the coefficient of the substances are multiplied or divided by some number , the value of ΔH is multiplied or divide by the same number.

6) If the reaction is reversed ,the sign of ΔH changes but the magnitude remains the same.

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