1-¿Cuáles son las 5 formas más comunes de identificar un cambio químico? 2-Escribe tres ejemplos de cambios químicos en los que se observe un cambio temperatura sin aplicar calor.
3-Escribe tres ejemplos de cambios químicos en los que se observe un cambio de color

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explanation:

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol