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Help with chemical equations?
I'm working through a chemistry study guide and have come across some questions I am having trouble figuring out. I have looked through my notes but cannot seem to figure out how to solve these problems. They are:
1. How many moles of NaOH will be produced if we produce 1.85 moles of H2 in the reaction
2Na + 2 H2O ->2 NaOH + H2
Answer: 3.7 moles
2. How many moles of MnO2 are needed if we want to make 5.63 moles of O2 by the reaction
3 MnO2 -> Mn3O4 + O2
Answer: 16.9 moles
3. How many moles of NaCl are needed if we want to make 4.81 moles of AgCl by the reaction
NaCl + AgNO3 -> AgCl + NaNO3
Answer: 4.81 moles
4. How many moles of NaCl are needed if we want to make 3.37 moles of PbCl2 by the reaction
2NaCl + Pb(NO3)2 -> PbCl2 + 2 NaNO3
Answer: 6.74 moles
5. How many moles of KClO3 are needed to produce 6.88 moles of O2 in the reaction
2KClO3 -> 2 KCl + 3 O2
Answer: 4.59 moles
Any help with any of these problems would be greatly appreciated! Thank you in advance for your help!
6 Answers
- rpmalaniLv 51 decade agoFavorite Answer
1. How many moles of NaOH will be produced if we produce 1.85 moles of H2 in the reaction
2Na + 2 H2O ->2 NaOH + H2
With each mole of H2 produced 2 mole NaOH is produced. so for 1.85 mole H2 1.85*2 = 3.7 mole NaOH is produced.
All questions are similar. you need to apply the unitary method in all question
- sandieLv 51 decade ago
1. The equation tells you that for every 1 mole of H2 formed, 2 moles of NaOH are also formed. So if you produce 1.85 moles H2 you must also produce (2 x 1.85) = 3.7 moles NaOH
2 1 mol O2 needs 3 moles MnO2 so 5.63 moles O2 needs (3 x 5.63) = 16.9 moles MnO2
and so on. All done the same way
- 1 decade ago
I will just explain on the first example, rest of it it's same. So:
1. How many moles of NaOH will be produced if we produce 1.85 moles of H2 in the reaction
2Na + 2 H2O ->2 NaOH + H2
Answer: 3.7 moles... just look at the numbers before each compound in equation.Numbers are relation between moles of those compounds. So in front of H2 there is no number,cuz its just one mol. And in front of NaOH is 2. So 1 mol of H2 is in relation with two moles of NaOH. so just multiply 1.85 by 2.
also in example number 2 : 3moles of MnO2 are in relation with 1 of O2. So for making 5,36 moles of O2 you'l need 3 times more MnO2.
- magik ;)Lv 51 decade ago
For these kinds of questions, you just need to multiply what they give you with the mole ratio.
Like in #1, you are give H2, but you want NaOH. Based on the equation, you can see that for every 2 moles of NaOH, there is 1 mole of H2. The mole ratio then, would be 2mol NaOH / 1mol H2.
Now you just set it up so that the correct units will cancel, and multiply:
1.85mol H2 * 2mol NaOH / 1mol H2 = 3.7mol NaOH.
It's basically the same for the rest of the problems. Hope this helped :)
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- 1 decade ago
When you balance an equation you put those numbers in front of the formulas... and they equate to the ratio of moles so therefore in the first one you can see that you have double the amount of NaOH as you do H2 so therefore if you produce 1.85 moles of H2 you will produce double the amount of NaOH therefore 3.7 moles... it works the same for the rest
- 1 decade ago
The numbers preceding compounds give their ratio in moles to each other.
1. We have one lot of H2 (1.85mol) and two lots of NaOH, so we multiply 1.85 by 2 giving 3.7 moles
2. Three lots of MnO2 are required to give one lot of O2 (5.63mol) so 5.63 is multiplyed by 3 giving 16.89 moles
I hope this helps with the rest (:
