How does the law of conservation of mass apply to this reaction: mg + hcl + h2 + mgcl2 ?
hydrogen and chlorine need to be balanced. there is an equal amount of magnesium
on each side
the equation needs to be balanced. there are fewer hydrogen atoms in the equation
than magnesium or chlorine.
the law of conservation of mass has already been applied. there is an equal number
of each element on both sides of the equation.
only the hydrogen needs to be balanced. there are equal numbers of magnesium and
chlorine
finish

Hydrogen and chlorine need to be balanced. There is an equal amount of magnesium on each side.

Explanation:

The given chemical equation does not hold the law of conservation of mass because the number of atoms of hydrogen and chlorine are not balanced on each side.

Chemical equation:

Mg + HCl  → MgCl₂ + H₂

Balanced chemical equation:

Mg + 2HCl  → MgCl₂ + H₂

Now this equation hold the law of conservation of mass.

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

Explanation:

This law was given by french chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

most historians agree that gabriel mouton, the vicar of st. paul’s church in lyons, france, is the “founding father” of the metric system. he proposed a decimal system of measurement in 1670. mouton based it on the length of one minute of arc of a great circle of the earth (now called a nautical mile, 1852 meters). he also proposed the swing-length of a pendulum with a frequency of one beat per second as the unit of length (about 25 cm). a pendulum beating with this length would have been fairly easy to produce, thus facilitating the widespread distribution of uniform standards. over the years, his work was revised, improved, and extended by a number of french scientists.

the political sponsor of weights and measures reform in the french revolutionary national assembly was the bishop of autun, better known as talleyrand. under his auspices, the french academy appointed several committees to carry out the work of developing a usable system of weights and measures for france. one of the committees recommended a decimalized measurement system based upon a length equal to one ten-millionth of the length of a quadrant of the earth’s meridian (i.e., one ten-millionth of the distance between the equator and the north pole).