Under appropriate conditions, nitrogen and hydrogen undergo a combination reaction to yield ammonia: N 2 (g) 3H 2 (g) 2NH3 (g) If the reaction yield is 87.5%, how many moles of N 2 are needed to produce 3.00 mol of NH 3

We need 1.714 moles N2

Explanation:

Step 1: Data given

The reaction yield = 87.5 %

Number of moles NH3 produced = 3.00 moles

Step 2: The balanced equation

N2(g)+ 3H2(g) →2NH3(g)

Step 3: Calculate moles N2

For 2 moles NH3 produced we need 1 mol N2 and 3 moles H2

This means, if the yield was 100%, for 3.00 moles NH3 produced , we need 1.5 moles N2

For a 87.5 % yield:  

we need more N2, increased by a ratio of 100/87.5.

100/87.5 * 1.5 =  1.714 moles N2

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.