The reaction for the decomposition of ammonia (nh3) can be written as shown. if a student starts with 21.7 g of ammonia, how many grams of hydrogen gas (h2) will be produced by the reaction?

- 3.83 g of hydrogen gas are formed.

Solution:- It is a stoichiometry problem and could easily be solved using dimensional analysis. The balanced equation for the decomposition of ammonia gas to give nitrogen and hydrogen gases is:

From balanced equation, there is 2:3 mol ratio between ammonia and hydrogen. We start with given grams of ammonia and convert them to moles on dividing the grams by molar mass.

In next step the moles of ammonia are multiplied by mol ratio to get the moles of hydrogen which are finally multiplied by it's molar mass to get the grams of hydrogen gas formed.

The set is shown below:

=

So, from the calculations 3.83 g of hydrogen gas are formed by the decomposition of 21.7 g of ammonia gas.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

tracks, burrows, eggshells, nests, tooth marks, or gastroliths