One reaction that produces hydrogen gas can be represented by the unbalanced chemical
equation
Mg(s) + HCl(aq) −→ MgCl2(aq) + H2(g).
What mass of HCl is consumed by the reaction of 3.15 mol of magnesium?
Answer in units of g.

h let me think

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.

answer; 4 electrons;

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.