### 35cm3 of hydrogen was sparkled with 12cm3 of oxygen at 110°c and 760mmHg to produce...

35cm3 of hydrogen was sparkled with 12cm3 of oxygen at 110°c and 760mmHg to produce steam.What percentage of the total volume of gas left after the reaction is hydrogen.
A)11%
B)31%
C)35%
D)69%

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Maranatha Okpako
1 week ago
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isaaq
1 week ago
2H2 + O2 = 2H2O
2vol 1vol 2vol
35cm^3 12cm^3 -
multiply their coefficient by d lowest volume
24cm^3 12cm^3 24cm^3
use d original vol. Given 2 substract d 1 gotten
11cm^3 - 24cm^3
total volume of residual=11+24
=35cm^3
percentage residue of hydrogen =11/35 *100%= 31.43%
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love_proxy
1 week ago
Pls where did the 24 come from??
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• Maranatha Okpako: Let me put it this way sha.
From the equation of the reaction, 2 moles of Hydrogen reacts with mole of Oxygen to produce 2 moles of Water.

Therefore the volumes reacting must be in that same volume in such a way that there is only one excess reactant and the other reactant has to be exhausted.

The reactant exhausted is called the limiting reagent.
So let us try both reagents to see which one is fitting to be limiting reagent.

if we try Hydrogen.
35cm³
in order to make it a ratio of 2:1 with Oxygen, we have to divide by 2
35/2=17.5cm³ this is more than the available volume of Oxygen. (12cm³)Therefore be the limiting agent.

Now to try Oxygen which obviously has to be the limiting reagent. (since there can only be one)

The ratio of Hydrogen to Oxygen is 2:1
therefore to find the Volume of Hydrogen from Oxygen we multiplly by 2.
12x2=24cm³

This way. Oxyegn is exhausted and Hydrogen is excess.
1 week ago
• Maranatha Okpako: i hope you get??
1 week ago
• love_proxy: Yeah i do!,thanks alot!.
1 week ago
love_proxy
1 week ago
How did you get the 24?
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• Ceejay69: 12cm3 of oxygen only requires 24 cm3 of hydrogen to give 24cm3 of steam
1 week ago
• Ceejay69: 35cm3 of hydrogen was given but only 24cm3 of it will react with the oxygen
So the gases left will be 11cm3 of hydrogen and 24cm3 of steam. It is steam because the reaction is carried out at 110 degrees celsius.
The total volume of gases left will now be
11cm3(Hydrogen) +24cm3(steam)= 35cm3
The percentage of hydrogen in this is
11/35
=31%
1 week ago
love_proxy
1 week ago
The question here is why is it reacting with just 24??,is it because the M.M of oxygen is 24??,or is it because of another reason?
That's my problem here.
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• Ceejay69: It is gay lussac's law of combining volumes.
From the reaction, 2moles of hydrogen will combine with one mole of oxygen to give two moles of steam
So the ratio is 2:1:2
Oxygen is the limiting reactant, so even it they gave 50cm3 of oxygen, it will react with 100cm3 of hydrogen to give 100cme of steam
If they give 5cm3 of oxygen, it will react with 10cm3 of hydrogen to give 10cm3 of steam
1 week ago
• Ceejay69: Note that this only works for gases
1 week ago
• Ceejay69: Note that this law only works for gases
1 week ago
• Ceejay69: Just try and read gay lussac's law again. It's very important you know how to solve such questions. They are so common in Jamb
1 week ago