Stoichiometric reactions

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Radha Patel 4I
Posts: 97
Joined: Tue Feb 12, 2019 12:15 am

Stoichiometric reactions

Postby Radha Patel 4I » Thu Jun 27, 2019 10:12 am

Could someone explain how you are supposed to understand stoichiometric reactions. For instance, in the chemical equation N2(g) +3H2(g) -> 2NH3 (g), how and why is 1 mol N2 chemically equivalent to 3 mol H2 and 2 mol NH3?

Leah farhadi 1F
Posts: 36
Joined: Mon Jun 17, 2019 7:23 am

Re: Stoichiometric reactions

Postby Leah farhadi 1F » Thu Jun 27, 2019 10:22 am

Since this is a balanced chemical equation, N2 +3H2 -> 2NH3, the stoichiometric coefficients summarize the number of moles of reactants and products taking part in the reaction. Since we understand this we can make mole-to-mole predictions using mole ration which allows the compounds in the chemical reaction to be related to the amount of product produced. In other words, the balanced chemical equation for a reaction is used to set up the mole ratio, which is used to convert amount of one substance into the amount of another.

i.e. mol NH3 = 1 mol N2 x (2 mol NH3/1 mol N2) => mol N2 cancels and we are left with 2 mol NH3 is produced from 1 mol N2

205458163
Posts: 33
Joined: Wed Jun 26, 2019 12:15 am

Re: Stoichiometric reactions

Postby 205458163 » Sat Jun 29, 2019 2:50 pm

The key is the fraction. In a chemical reaction, the stoichiometric coefficient represents the fraction of each chemical substance. Because of the fraction of N2 H2 and NH3 is 1:3:2, the amount's fraction of them is also 1:3:2. Thus, when the N2 is 1mol, H2 is 3mol, NH3 is 2mol.

jlinwashington1B
Posts: 65
Joined: Fri Sep 28, 2018 12:22 am

Re: Stoichiometric reactions

Postby jlinwashington1B » Thu Jul 04, 2019 1:14 pm

This equation is balanced on both sides... Each nitrogen has 2, while each hydrogen has 6 ( 2x3=6). Thus, this equation is not based on equivalence, but rather making sure that each element has the correct coefficients on both sides to get that stable balance.

Junxi Feng 3B
Posts: 52
Joined: Sat Sep 14, 2019 12:17 am

Re: Stoichiometric reactions

Postby Junxi Feng 3B » Fri Sep 27, 2019 6:25 pm

Just need to make sure that the coefficients of each element on both sides of the chemical equation is equivalent (or balanced).

lasarro
Posts: 55
Joined: Thu Jul 11, 2019 12:15 am

Re: Stoichiometric reactions

Postby lasarro » Fri Sep 27, 2019 6:42 pm

With stoichiometric problems, think about it as an equation. An equation such as 1=2 is simply not true. In chemistry, it's essentially the same concept. You have to have the same number of atoms on each side of the equation. So if you have N2 on one side you have to have N2 on the other side. The coefficients multiply the number of atoms in the molecule it is in front of.


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