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# Ocr chemistry a as - someone plzzzz explain 1.1-9 moles and equations to me Watch

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1. Hey guys
I am new to the student room ..I know it says i joined last year but I never actually used it loool... so I am sorry if I am doing any thing wrong... for example I am posting this thread in the wrong section etc. but I hav my mock exam tomorrow and I am stuck on
1.1 - 9 Moles and reactions

I seriously do not get how to deduce the quantities of reactants and products from balanced equations

speciall the bit where it says
amount in equation
amount required

How do u find out the amounts required

plz explain to me the step by step procedure

THANKS A LOT IN ADVANCE GUYS
2. Well let's say we have the combustion of methane:

From the equation we see that 1 mole of methane reacts with 2 moles of oxygen which then produces 1 mole of carbon dioxide and 2 moles of water.

If we had 16g of methane we would require 64g of oxygen to produce 48g of and 36g of water

But if we had 4g of methane we would require 16g of oxygen to produce 12g of and 9g of water
All i've done is divide all values by 4

Hopefully this explanation is what you are after
3. (Original post by soup)
Well let's say we have the combustion of methane:

From the equation we see that 1 mole of methane reacts with 2 moles of oxygen which then produces 1 mole of carbon dioxide and 2 moles of water.

If we had 16g of methane we would require 64g of oxygen to produce 48g of and 36g of water

But if we had 4g of methane we would require 16g of oxygen to produce 12g of and 9g of water
All i've done is divide all values by 4

Hopefully this explanation is what you are after

basically let me givE u an example of a type of question related to this topic

q1) 2.529 g oF MgCO3 reacts with an eXcess of HNO3
(i) What volume of CO2 measured at RTP, is formed?
(ii) The final volume of the solution is 50.0 cm3. what is the concentration, in mol dm-3, of Mg(NO3)2 formed ?

I AM TOTALLY LOST
4. (Original post by godknowsprerna)

basically let me givE u an example of a type of question related to this topic

q1) 2.529 g oF MgCO3 reacts with an eXcess of HNO3
(i) What volume of CO2 measured at RTP, is formed?
(ii) The final volume of the solution is 50.0 cm3. what is the concentration, in mol dm-3, of Mg(NO3)2 formed ?

I AM TOTALLY LOST
Before you can even think to start the calculation you need to write out the balanced equation for the reaction in point...

... can you do this?
5. (Original post by charco)
Before you can even think to start the calculation you need to write out the balanced equation for the reaction in point...

... can you do this?

yhh i know how to balance equations [even though i do get stuck at times... but yhh i do hav the basic understanding sir ]

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Updated: November 28, 2010
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