Physics, Chemistry and Biology: Post your doubts here!

[$$$###]

what is the difference between empirical and molecular formula
can anyone help

 

[f.mohamed]

View attachment 43364
Awesome12
Why Argon?

Because calcium alone has 20 electrons while calcium ion which is Ca2+ has 18 electrons ... And Argon has 18 electrons
Ca2+ means it lost 2 electrons

 

[Phoenix Blood]

what is the difference between empirical and molecular formula
can anyone help

Empirical formulas show the simplest whole number ratio of these atoms.
Molecular formulas show the actual ratio of atoms in the compound.

Here is an example:

Glucose is the a simple sugar whose molecular formula is C6H12O6

Its empirical formula would be CH2O which would be its molecular formula divided by the smallest whole number

 

[Zsiddiqui]

First write the equation.

CxHy + O2 = CO2 + H2O

Volume of oxygen used = will be total oxygen used - oxygen not used.

175 cm^3 used, 25 not used so 175-25 = 150 cm^3.

Volume of carbon dioxide formed = volume of remaining gases - volume of oxygen unreacted
= 100 cm^3.

So your data now is.

20 cm^3 of the hydrocarbon reacted with 150 cm^3 of oxygen to form 100 cm^3 of Carbon dioxide.

The ratio is 2:15:10

Using this ratio you can find the number of moles of H2O that forms.

If the ratio of CO2 to H2O is 1:1.

15 moles produce 10 moles of CO2. Then 15 moles will also produce 10 moles of H20.

Your formula should look like this now.

2CxHy + 15O2 ------> 10CO2 + 10H2O.

there are 10 carbons on the left hand side.

So there must be 10 carbons on the right hand side, but there are 2 moles of the hydrocarbon so it will be 5 carbons on the left.

2C5Hy + 15O2 ------> 10CO2 + 10H2O.

There are 20 hydrogens on the right.

So there has to be 20 on the left.

but 2 moles of the hydrocarbon, makes it 10.

So final formula = C5H10 and final equation = 2C5H10 + 1502 -----> 10CO2 + 10H20.

Thankkk youu soo muchh !!! :*
I was soo confused bt nt now =D
So we dont need to take out the moles , the ratio of their volumes itself is the moles

 

[Zsiddiqui]

what is the difference between empirical and molecular formula
can anyone help

and for molecular formula . You also have to add the mass numbers of elements . while empirical is just the simple form

 

[ChubbyBunny]

View attachment 43360

true man... Now I am really worried about the GT.

 

[ChubbyBunny]

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what is the difference between empirical and molecular formula
can anyone help

Remember .. empirical is the ratio while molecular is the actual. It is the way I have always remembered hope it helps =)

 

[rida.12.!!]

7 The alcohols form a homologous series. The fi rst member of this series is methanol, CH3OH.
(ii) The mass of one mole of an r6tis 116 g. What is its formula?
Show your reasoning.
....................................................................................................................................
.............................................................................................................................. [2]

 

[rida.12.!!]

(b) Methanol is manufactured using the following method.
CH4(g) + H2O(g) → CO(g) + 3H2(g) reaction 1
CO(g) + 2H2(g) CH3OH(g) reaction 2
The conditions for reaction 2 are:
pressure 100 atmospheres
catalyst a mixture of copper, zinc oxide and aluminium oxide
temperature 250 °C
The forward reaction is exothermic.
(i) Why is high pressure used in reaction 2?
....................................................................................................................................
.............................................................................................................................. [2]12

(ii) Explain why using a catalyst at 250 °C is preferred to using a higher temperature of
350 °C and no catalyst.
....................................................................................................................................
....................................................................................................................................
.............................................................................................................................. [3]
(c) Methanol is oxidised by atmospheric oxygen. This reaction is catalysed by platinum.
(i) The products of this reaction include a carboxylic acid. Give its name and structural
formula.
name .......................................................
structural formula showing all bonds
[2]
(ii) Deduce the name of the ester formed by the reaction of methanol with the carboxylic
acid named in (i).
.............................................................................................................................. [1]

 

[rida.12.!!]

electrolysis of :
}dilute H2SO4
}aqueous Copper2sulfate

 

[ChubbyBunny]

the v) question please answer fast

 

[Xylferion]

the v) question please answer fast

O3 ---> O2
2O3 -----> 3O2

 

[eureka!]

And mass of air in the room, eureka!, what about it?

See, mass will probably decrease. Some air leaves the room out the window, so mass of air in the room decreases.

 

[eureka!]

Kaunsa salmon? Woh mota wala?
Less height, coz he's having more weight (more weight= more force, and since w=fd, force has increased, toh here you can see that force and distance are inversely proportional... .. so.... if force has increased, the distance should decrease ...)

idk, idk, wbu?

k.e. = g.p.e.
so 1/2mv^2 = hmg right?
so if mass increases by same amount on both sides, with v constant, height stays the same.
Flawed, twisted logic perhaps, but that was my answer.

And force is inversely proportional to distance only when work/energy is constant. But since g.p.e. is increasing too, I don't think this holds.

 

[ChubbyBunny]

O3 ---> O2
2O3 -----> 3O2

HOW ?

 

[slisjunknown]

HOW ?

2*3=6 and 3*2=6...so the equation is balanced

 

[Xylferion]

HOW ?

Ozone actually breaks up into O2 and Oxygen atoms.

So I think it's O3 -----> O2 + O

What does the ms say?

 

[ChubbyBunny]

Ozone actually breaks up into O2 and Oxygen atoms.

So I think it's O3 -----> O2 + O

What does the ms say?

I understood it and your explanation is right ...thanks a lottle =)

 

[R_Ma7mooD]

Guys for the exam do we need to memorize like bond energies and things like those, cuz its kinda impossible..

 

[hard_worker]

ANYONE PLZ!