which of the following chemical equations shows the law of conservation of mass?
A ) K+MgBR>KBR+Mg
B ) N2+H2>NH3
C ) P+O2>P2O5
D ) H2O+O2>H2O2
The law of conservation of mass states that in a chemical reaction, the mass of the products must equal the mass of the reactants. This means that the number of atoms of each element must be the same on both the reactant side and the product side of the equation.
Let's examine each of the options:
A) K + MgBr → KBr + Mg
This equation is not balanced, as the number of atoms for each element is not the same on both sides of the equation. There's also a typo; "MgBr" is likely meant to be "MgBr2" for magnesium bromide. As written, this equation does not follow the law of conservation of mass.
B) N2 + H2 → NH3
This equation is not balanced because there are two nitrogen atoms on the left side but only one nitrogen atom in one molecule of NH3 on the right side. Similarly, there are two hydrogen atoms on the left side, but one molecule of NH3 contains three hydrogen atoms. Thus, this equation does not show the law of conservation of mass in its current state.
C) P + O2 → P2O5
This equation is not balanced as written. There's one atom of phosphorus (P) on the left and two in the product P2O5. Also, there are two oxygen atoms (O2) on the left, but P2O5 has five oxygen atoms. Thus, this also does not show the law of conservation of mass as currently written.
D) H2O + O2 → H2O2
Let's balance this equation to see if it follows the law of conservation of mass:
On the left side, there are two hydrogen atoms and three oxygen atoms (two in O2 and one in H2O). On the right side, there are two hydrogen atoms and two oxygen atoms in H2O2. To balance the oxygen atoms, we could place a coefficient of 2 in front of H2O2, which would require half an O2 molecule:
2 H2O + O2 → 2 H2O2
Now the equation is balanced, with each side showing four hydrogen atoms and four oxygen atoms. Therefore, when correctly balanced, option D follows the law of conservation of mass, but as originally written, it is not balanced and therefore does not correctly demonstrate the law.
Please note that none of the equations as initially presented (A, B, C, and D) are balanced, and to follow the law of conservation of mass, they need to be correctly balanced. If we're forced to choose from the given options without balancing them, none of them explicitly show the law of conservation of mass. However, if we allow for balancing, option D can be modified to show the conservation of mass.