The mass of any substance will remain the same regardless of its state of matter. Using water as an example, its volume increases when it is boiled to a gas or when it is frozen from a liquid state to the solid state ice. The volume and temperature will change as it moves through the states of matter, however the amount of individual molecules of oxygen and hydrogen that form water will remain the same and this constitute mass.
<h3>Answer:</h3>
Phosphoric acid reacts with magnesium hydroxide to produce magnesium phosphate and water via the following reaction:
2H3PO4 + 3Mg(OH)2 → Mg3(PO4)2 + 6H2O
(solid) (solid) (solid) (liquid)
<h3>Explaination:</h3>
This is a typical neutralization reaction of an acid with a base to form a salt and water. The reaction is exothermic, gives off heat,
ΔH < 0 , and may be balanced by adding balancing numbers in front, ie adding molecules, in order to ensure that the total number of atoms of each element is the same on the left and right hand sides of the equation.
Doing so we obtain :
2H3PO4 + 3Mg(OH)2 → Mg3(PO4)2 + 6H2O
(solid) (solid) (solid) (liquid)
<h3>hope it helps :)</h3>