Physics, Chemistry and Biology: Post your doubts here!

[Mr.Physics]

hey any 3 physical and chemical differences between group 1 metals and transition metals ??

 

[Mr.Physics]

reactivity series (of metals n hydrogen is wat u need in d IGCSEs) :
please
stop
calling
me
a
crazy
zombie
if
that
large
hippo
can't
swim
gug glug!
plug plug!
first letter of each word denotes d first letter of each metal in order <_<

wt about the test for anions and cations ??
those get really mixed up !

 

[Mr.Physics]

Oxidation may be :
1. gain of 02
2. gain of hydrogen
3. loss of electons
Reduction is the exact opposite of it.

Redox reactions are where oxidation and reduction take place at the same time in a chemical reaction. And you don't "calculate" whether they occur or not, they just do. See in the example you gave (NO + O3 ---> NO2 +O2), nitrogen-dioxide has gained oxygen, and has thus gotten oxidized (oxidation). 03 has lost an oxygen molecule, and thus gotten reduced ( reduction). So u see? oxidation n reduction r taking place in d same chemical reaction side by side. check for the loss and gain of oxgen, hydrogen and electons in any given reaction to know whether it is redox >_>

Simplifying an equation is just how you reduce numbers in mathematics

And i can't get wt are oxidising agents and reducing agents ?? some call them oxidants and reductants ???

 

[Phoenix Blood]

hey any 3 physical and chemical differences between group 1 metals and transition metals ??

physical -
transition metals hav higher density, stronger tensile strength, higher MP and BP, whereas group 1 metals hav d exact opposite of these properties.

Chemical-
group 1
metals have only one valency +1
react violently with water
Burn vigorously in air oxygen and chlorine
react explosively with acids
react violently with sulphur and phosphorus
form soluble halides
form colourless compounds
don`t catalyse many reactions
transition metals
have variable oxidation states
form coloured compounds
form complex ions with water, ammonia etc
Good catalysts many examples
less reactive with water or dilute acids (slow reactions sometimes no reaction at all)
Iron (example steel wool) does burn in chlorine but many others do not react well with Halogens
transition metal compounds are powerful oxidising agents in some cases eg MnO4 aq Cr2O7 aq

Hope that helps

 

[Phoenix Blood]

wt about the test for anions and cations ??
those get really mixed up !

hardly anything --> http://www.creative-chemistry.org.uk/gcse/documents/Module22/N-m22-02.pdf

 

[Phoenix Blood]

And i can't get wt are oxidising agents and reducing agents ?? some call them oxidants and reductants ???

Redox reactions

Oxidation and reduction in terms of oxygen transfer
Definitions

• Oxidation is gain of oxygen.
• Reduction is loss of oxygen.

For example, in the extraction of iron from its ore:

Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction.

Oxidising and reducing agents
An oxidising agent is substance which oxidises something else. In the above example, the iron(III) oxide is the oxidising agent.

A reducing agent reduces something else. In the equation, the carbon monoxide is the reducing agent.

• Oxidising agents give oxygen to another substance.
• Reducing agents remove oxygen from another substance.

Oxidation and reduction in terms of hydrogen transfer
These are old definitions which aren't used very much nowadays. The most likely place you will come across them is in organic chemistry.

Definitions

• Oxidation is loss of hydrogen.
• Reduction is gain of hydrogen.

Notice that these are exactly the opposite of the oxygen definitions.

For example, ethanol can be oxidised to ethanal:

You would need to use an oxidising agent to remove the hydrogen from the ethanol. A commonly used oxidising agent is potassium dichromate(VI) solution acidified with dilute sulphuric acid.

Ethanal can also be reduced back to ethanol again by adding hydrogen to it. A possible reducing agent is sodium tetrahydridoborate, NaBH4. Again the equation is too complicated to be worth bothering about at this point.

An update on oxidising and reducing agents

• Oxidising agents give oxygen to another substance or remove hydrogen from it.
• Reducing agents remove oxygen from another substance or give hydrogen to it.

Oxidation and reduction in terms of electron transfer
This is easily the most important use of the terms oxidation and reduction.

Definitions

• Oxidation is loss of electons
• Reduction is gain of electrons.

It is essential that you remember these definitions. There is a very easy way to do this. As long as you remember that you are talking about electron transfer:

OIL
RIG
Oxidation IsLossReduction IsGain
A simple example
The equation shows a simple redox reaction which can obviously be described in terms of oxygen transfer.

CuO + Mg → Cu + MgO

Copper(II) oxide and magnesium oxide are both ionic. The metals obviously aren't. If you rewrite this as an ionic equation, it turns out that the oxide ions are spectator ions and you are left with:

A last comment on oxidising and reducing agents
If you look at the equation above, the magnesium is reducing the copper(II) ions by giving them electrons to neutralise the charge. Magnesium is a reducing agent.

Looking at it the other way round, the copper(II) ions are removing electrons from the magnesium to create the magnesium ions. The copper(II) ions are acting as an oxidising agent.

Warning!
This is potentially very confusing if you try to learn both what oxidation and reduction mean in terms of electron transfer, and also learn definitions of oxidising and reducing agents in the same terms.

It is recommend that you work it out if you need it. The argument (going on inside your head) would go like this if you wanted to know, for example, what an oxidising agent did in terms of

• An oxidising agent oxidises something else.
• Oxidation is loss of electrons.
• That means that an oxidising agent takes electrons from that other substance.
• So an oxidising agent must gain electrons.

Or you could think it out like this:

• An oxidising agent oxidises something else.
• That means that the oxidising agent must be being reduced.
• Reduction is gain of electrons
• So an oxidising agent must gain electrons.

Understanding is a lot safer than thoughtless learning

 

[Atharva Joshi]

Redox reactions

Oxidation and reduction in terms of oxygen transfer
Definitions

• Oxidation is gain of oxygen.
• Reduction is loss of oxygen.

For example, in the extraction of iron from its ore:

Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction.

Oxidising and reducing agents
An oxidising agent is substance which oxidises something else. In the above example, the iron(III) oxide is the oxidising agent.

A reducing agent reduces something else. In the equation, the carbon monoxide is the reducing agent.

• Oxidising agents give oxygen to another substance.
• Reducing agents remove oxygen from another substance.

Oxidation and reduction in terms of hydrogen transfer
These are old definitions which aren't used very much nowadays. The most likely place you will come across them is in organic chemistry.

Definitions

• Oxidation is loss of hydrogen.
• Reduction is gain of hydrogen.

Notice that these are exactly the opposite of the oxygen definitions.

For example, ethanol can be oxidised to ethanal:

You would need to use an oxidising agent to remove the hydrogen from the ethanol. A commonly used oxidising agent is potassium dichromate(VI) solution acidified with dilute sulphuric acid.

Ethanal can also be reduced back to ethanol again by adding hydrogen to it. A possible reducing agent is sodium tetrahydridoborate, NaBH4. Again the equation is too complicated to be worth bothering about at this point.

An update on oxidising and reducing agents

• Oxidising agents give oxygen to another substance or remove hydrogen from it.
• Reducing agents remove oxygen from another substance or give hydrogen to it.

Oxidation and reduction in terms of electron transfer
This is easily the most important use of the terms oxidation and reduction.

Definitions

• Oxidation is loss of electons
• Reduction is gain of electrons.

It is essential that you remember these definitions. There is a very easy way to do this. As long as you remember that you are talking about electron transfer:

OIL
RIG
Oxidation IsLossReduction IsGain
A simple example
The equation shows a simple redox reaction which can obviously be described in terms of oxygen transfer.

CuO + Mg → Cu + MgO

Copper(II) oxide and magnesium oxide are both ionic. The metals obviously aren't. If you rewrite this as an ionic equation, it turns out that the oxide ions are spectator ions and you are left with:

A last comment on oxidising and reducing agents
If you look at the equation above, the magnesium is reducing the copper(II) ions by giving them electrons to neutralise the charge. Magnesium is a reducing agent.

Looking at it the other way round, the copper(II) ions are removing electrons from the magnesium to create the magnesium ions. The copper(II) ions are acting as an oxidising agent.

Warning!
This is potentially very confusing if you try to learn both what oxidation and reduction mean in terms of electron transfer, and also learn definitions of oxidising and reducing agents in the same terms.

It is recommend that you work it out if you need it. The argument (going on inside your head) would go like this if you wanted to know, for example, what an oxidising agent did in terms of

• An oxidising agent oxidises something else.
• Oxidation is loss of electrons.
• That means that an oxidising agent takes electrons from that other substance.
• So an oxidising agent must gain electrons.

Or you could think it out like this:

• An oxidising agent oxidises something else.
• That means that the oxidising agent must be being reduced.
• Reduction is gain of electrons
• So an oxidising agent must gain electrons.

Understanding is a lot safer than thoughtless learning

Very Helpful

 

[Counter Logic Gamer]

i understood later...... anyways thnx for you your interest to help!!!

 

[Mr.Physics]

Redox reactions

Oxidation and reduction in terms of oxygen transfer
Definitions

• Oxidation is gain of oxygen.
• Reduction is loss of oxygen.

For example, in the extraction of iron from its ore:

Because both reduction and oxidation are going on side-by-side, this is known as a redox reaction.

Oxidising and reducing agents
An oxidising agent is substance which oxidises something else. In the above example, the iron(III) oxide is the oxidising agent.

A reducing agent reduces something else. In the equation, the carbon monoxide is the reducing agent.

• Oxidising agents give oxygen to another substance.
• Reducing agents remove oxygen from another substance.

Oxidation and reduction in terms of hydrogen transfer
These are old definitions which aren't used very much nowadays. The most likely place you will come across them is in organic chemistry.

Definitions

• Oxidation is loss of hydrogen.
• Reduction is gain of hydrogen.

Notice that these are exactly the opposite of the oxygen definitions.

For example, ethanol can be oxidised to ethanal:

You would need to use an oxidising agent to remove the hydrogen from the ethanol. A commonly used oxidising agent is potassium dichromate(VI) solution acidified with dilute sulphuric acid.

Ethanal can also be reduced back to ethanol again by adding hydrogen to it. A possible reducing agent is sodium tetrahydridoborate, NaBH4. Again the equation is too complicated to be worth bothering about at this point.

An update on oxidising and reducing agents

• Oxidising agents give oxygen to another substance or remove hydrogen from it.
• Reducing agents remove oxygen from another substance or give hydrogen to it.

Oxidation and reduction in terms of electron transfer
This is easily the most important use of the terms oxidation and reduction.

Definitions

• Oxidation is loss of electons
• Reduction is gain of electrons.

It is essential that you remember these definitions. There is a very easy way to do this. As long as you remember that you are talking about electron transfer:

OIL
RIG
Oxidation IsLossReduction IsGain
A simple example
The equation shows a simple redox reaction which can obviously be described in terms of oxygen transfer.

CuO + Mg → Cu + MgO

Copper(II) oxide and magnesium oxide are both ionic. The metals obviously aren't. If you rewrite this as an ionic equation, it turns out that the oxide ions are spectator ions and you are left with:

A last comment on oxidising and reducing agents
If you look at the equation above, the magnesium is reducing the copper(II) ions by giving them electrons to neutralise the charge. Magnesium is a reducing agent.

Looking at it the other way round, the copper(II) ions are removing electrons from the magnesium to create the magnesium ions. The copper(II) ions are acting as an oxidising agent.

Warning!
This is potentially very confusing if you try to learn both what oxidation and reduction mean in terms of electron transfer, and also learn definitions of oxidising and reducing agents in the same terms.

It is recommend that you work it out if you need it. The argument (going on inside your head) would go like this if you wanted to know, for example, what an oxidising agent did in terms of

• An oxidising agent oxidises something else.
• Oxidation is loss of electrons.
• That means that an oxidising agent takes electrons from that other substance.
• So an oxidising agent must gain electrons.

Or you could think it out like this:

• An oxidising agent oxidises something else.
• That means that the oxidising agent must be being reduced.
• Reduction is gain of electrons
• So an oxidising agent must gain electrons.

Understanding is a lot safer than thoughtless learning

wow awesome !!! thx

 

[Phoenix Blood]

i understood later...... anyways thnx for you your interest to help!!!

wow awesome !!! thx

Welcome

 

[Sara.H]

I have a confusion sorry ..How it will have a double bond and it's not alkene like alcohols only have a functional group and its isomers differs by the position of the OH !!??
I donknow if am Right !!!

 

[Phoenix Blood]

View attachment 49737 I have a confusion sorry ..How it will have a double bond and it's not alkene like alcohols only have a functional group and its isomers differs by the position of the OH !!??
I donknow if am Right !!!

Afzal1 <_<

 

[Afzal1]

Afzal1 <_<

actually the attachment stated that ethane 1,2 diol had double bonds... but no...
ethane1,2 diol has two OH groups attached to both the carbon atoms in the chain... so thats why th numbers are (1, 2)
and the word diol rfers clearly to two OH groups... so Phoenix Blood whatever u thought was correct.

and if there was a double bond then the name would be (ethene1,2 diol) the ene shows a double bond
i hope i have answered the qs to ur satisfaction

 

[♣♠ Magnanimous ♣♠]

actually the attachment stated that ethane 1,2 diol had double bonds... but no...
ethane1,2 diol has two OH groups attached to both the carbon atoms in the chain... so thats why th numbers are (1, 2)
and the word diol rfers clearly to two OH groups... so Phoenix Blood whatever u thought was correct.

and if there was a double bond then the name would be (ethene1,2 diol) the ene shows a double bond
i hope i have answered the qs to ur satisfaction

It's completely correct.

 

[Afzal1]

It's completely correct.

thanks a lot

 

[Sara.H]

actually the attachment stated that ethane 1,2 diol had double bonds... but no...
ethane1,2 diol has two OH groups attached to both the carbon atoms in the chain... so thats why th numbers are (1, 2)
and the word diol rfers clearly to two OH groups... so Phoenix Blood whatever u thought was correct.

and if there was a double bond then the name would be (ethene1,2 diol) the ene shows a double bond
i hope i have answered the qs to ur satisfaction

Yes..That's what I thought too ! But still what will be the answer for the Main ques

 

[NOneed2speedd]

Hello. .. this my first post in this forum...please someone help me with this

 

[NOneed2speedd]

And these two also

 

[Ushnaaa]

About physics,
Can anybody tell me whats included in paper 1,4 and 6?

 

[Phoenix Blood]

Hello. .. this my first post in this forum...please someone help me with this

Notice the way the boiling tubes are held.