Brainliesttme : )
if you were to measure the mass of magnesium and hydrochloric acid before combining them in the test tube, how would that mass compare to the mass of reactants left in the test tube after the reaction? explain your answer and how it corresponds to the law of conservation of mass.

Here's what I get.

Explanation:

Mg + 2HCl ⟶ MgCl₂ + H₂

According to the Law of Conservation of Mass, the total mass of the products must equal the total mass of the reactants.

However, one of the products is a gas, hydrogen. The gas escapes into the atmosphere, so you will not be weighing it at the end of the reaction.

The mass of the test tube and contents after the reaction will be less than before the reaction.

However, that doesn't violate the Law of Conservation of Mass. You just didn't measure the mass of all the products.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.