### 7A. 1 in the 7th edition

Posted:

**Mon Mar 04, 2019 4:33 pm**What is the question trying to ask? I am extremely confused on this one.

Created by Dr. Laurence Lavelle

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https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=146&t=43600

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Posted: **Mon Mar 04, 2019 4:33 pm**

What is the question trying to ask? I am extremely confused on this one.

Posted: **Mon Mar 04, 2019 4:36 pm**

it's similar to what Lavelle went over on Friday in lecture to where you treat it like a ratio

Posted: **Mon Mar 04, 2019 5:28 pm**

you basically just have to look at the ratios of the gases they're asking for.

For a) the ratio of N2 to H2 is 1:3, so the rate N2 is consumed at would be 1/3 the rate of consumption of H2

For a) the ratio of N2 to H2 is 1:3, so the rate N2 is consumed at would be 1/3 the rate of consumption of H2

Posted: **Mon Mar 04, 2019 5:32 pm**

This question is basically asking you to compare their rates, which can be determined by looking at their stoichiometric coefficients.

In this question, you're given the equation A+3B --> 2C. You know that A will be decreasing 3 times slower than B because only one mole of A is decomposing for every 3 moles of B. Logically, it makes sense that B would decompose at a rate 3 times faster than A. You can apply this logic to a reactant and product too. For every one mole of A that decomposes, it will form 2 moles of C. Therefore, the rate of formation of C is two times faster than the decomposition of one mole of A.

In this question, you're given the equation A+3B --> 2C. You know that A will be decreasing 3 times slower than B because only one mole of A is decomposing for every 3 moles of B. Logically, it makes sense that B would decompose at a rate 3 times faster than A. You can apply this logic to a reactant and product too. For every one mole of A that decomposes, it will form 2 moles of C. Therefore, the rate of formation of C is two times faster than the decomposition of one mole of A.

Posted: **Thu Mar 07, 2019 9:19 pm**

Basically isolate what you are looking at in the equation to the gases that the question is asking about and then set them equal to each other. If you divide the molar coefficients (what side you solve for depends on what chemical the question is asking about) and you will get the ratio of the rate of either formation or decomposition.