1. Hydrogen can be obtained from water by its decomposition by electric current. We compose the reaction equation for the decomposition of a water molecule. The reaction products are hydrogen and oxygen.
2. We compose the equation of the reaction between nitrogen and hydrogen.
a) We arrange the oxidation states of each element. We write out the elements that have changed their oxidation states.
b) Find the number of electrons given or received by these elements (we subtract the final one from the initial oxidation state). Nitrogen is an oxidizing agent, since it accepts electrons, while itself being oxidized.
Hydrogen is a reducing agent, as it donates electrons and is oxidized.
c) We find the common multiple for the found electrons (for the number 3 and 1, we divide by these numbers, respectively, we find the coefficients for the elements – these are the numbers 1 and 3). We double the found coefficients.
d) We put in the equation, starting from the right side.
3). Ammonia reacts with acids. We make the equation of ammonia with sulfuric acid.
4) To obtain ammonium chloride from ammonium sulfate, we compose the reaction equation with barium chloride, since the reaction must result in either gas, or water, or a precipitate. Barium ions with sulfate ions give a precipitate – barium sulfate.