The enthalpy of a reaction for a chemical change can be determined by

Explanation:

The enthalpy of a reaction for a chemical change can be determined by

Using the formula ∆H = m x s x ∆T to solve.

∆H is the change in the enthalpy of the reaction.

where,  m, the mass of our reactants,

s, the specific heat of our product,

and ∆T, the temperature change during the reaction,

Thus, we are ready to calculate the enthalpy of reaction.

Simply we can put in values into the formula ∆H = m x s x ∆T and multiply to solve.

it can be observed without changing the identity of the object.

it depends on what substance you're talking about as well as many other factors. in quantum mechanics, the observation of particles affects the observers ability to measure certain properties. for example: you can know the velocity of a particle, but you can't know it's position; or you can know it's position, but not it's velocity. it's like trying to find out where a grain of sand is by throwing other grains of sand at it. once you find out where it is, it's been moved. it's also like trying to find an answer to the question of whether or not a tree falling in a forest makes a sound if nobody is there to hear it. paradoxically, the only way to find out is to be there and hear it.