HHHEEELLLLLLPPPPP!!!CHEM DOUBT

[slisjunknown]

I have my exams in 2 hrs and need help urgently
When iron is placed in salt water, does the rusting slow down?Does salt water affect the rusting when placed in a current?
Please tell me the answer asap

 

[Master Minds]

I have my exams in 2 hrs and need help urgently
When iron is placed in salt water, does the rusting slow down?Does salt water affect the rusting when placed in a current?
Please tell me the answer asap

I am not sure... rusting needs oxygen and water only.. may be it slows down as in salt water, amount of oxygen will decrease.. But i m not sure if that is correct

i have question too. what type of chemical reaction is aqueous lead nitrate + aqueous lead chloride???

I doubt even if lead nitrate reacts with lead chloride.....

 

[qpKillerqp]

When metals rust, it forms metal oxides. But by definition, Catalyst Speeds up the process of the Rxn but does not get used up. However as you can see in the equation below, Oxygen is consumed with metal to for metal oxide. Therefore Oxygen CAN'T be a catalyst. It is a reactant.

Fe + O2 ---> Fe2O3

The Correct answer is SALT. (Sodium in NaCl for an example)

Rust is the process of metal oxidizing into metal oxide. The oxidation needs a transfer medium to occur, such as water. Salt in the water speeds up the oxidation process by acting as a catalyst. The salt is never used up and the problem with salt is that even when water is gone, it remains and wait to restart the forming of rust once more moisture is present. This is why metals rust much easily in salty areas such as beaches and cold states where they use salt to melt the icy roads.

 

[Bigbigboi]

I have my exams in 2 hrs and need help urgently
When iron is placed in salt water, does the rusting slow down?Does salt water affect the rusting when placed in a current?
Please tell me the answer asap

Rusting is faster because salt is an electrolyte, anyway if you are doing paper 62, revise on the thermit reactions, it is asked in the last question for 6 marks on how to obtain pure lead from lead carbonate!

 

[Master Minds]

sorry i meant potassium chloride and they will give lead chloride sorry

potassium chloride + lead nitrate .... both are soluble salts n react to give an insoluble salt.. lead chloride. this is precipitate mehtod of salt preparation of an insoluble salt from soluble reactants.

 

[Master Minds]

so the type of chemical rection is precipitation

Yes

 

[slisjunknown]

Rusting is faster because salt is an electrolyte, anyway if you are doing paper 62, revise on the thermit reactions, it is asked in the last question for 6 marks on how to obtain pure lead from lead carbonate!

Thnx 4 de tip.I am doing 62 .... what are thermit reactions, anyways??

 

[slisjunknown]

and in fractional distillation of ethanol and butanol how can u know if all the ethanol was collected?

The temperature on the thermometer remains at 78c(I guess that's the b.p. of ethanol) until all the ethanol leaves

 

[FlameBlazer69]

I wrote the exam. The last page was a brain twister

 

[qpKillerqp]

Well I didn't have any problem(Alhamdu lillah)except for the question which said : How are crystals separated from the solution.I wrote filtration.Is that correct?

 

[qpKillerqp]

The temperature on the thermometer remains at 78c(I guess that's the b.p. of ethanol) until all the ethanol leaves

Can we also say when the mixture/solution stops boiling(no more bubbles throughout the liquid) ???

 

[shadowy4646]

why is the mixture of phenylamine and benzenediazonium mixed vigorously?????????

 

[qpKillerqp]

why is the mixture of phenylamine and benzenediazonium mixed vigorously?????????

Sorry but I think this is a different variant than us

 

[FlameBlazer69]

I did variant 62, what did yous do?

 

[Faheen]

so the type of chemical rection is precipitation

shouldnt they type of reaction be double diplacement since precipation is a method like titration but the type of reaction is neutrilsation

 

[shadowy4646]

Sorry but I think this is a different variant than us

Thanx i think so too!!

 

[jam331]

why is it that if you had put methyl orange in the first experiment and then u put phenolpthaline in the second it does not work?

 

[Faheen]

why is it that if you had put methyl orange in the first experiment and then u put phenolpthaline in the second it does not work?

im not sure but i think that firstly methyl orange would produce a more visible colur change so acid added would neutrilise the entire solution r\ since colour change is more prominent and secondly because when we later add phenophathalene colour of the solution would be colourless so it would be difficult to judge

 

[Bigbigboi]

In the question that they asked about obtaining ethene for ethane, the reason that the first test tube of gas was discarded was because it contained hydrogen right?

 

[Sariya Khan]

In the question that they asked about obtaining ethene for ethane, the reason that the first test tube of gas was discarded was because it contained hydrogen right?

No it contains mixture of air

• The first tube of gas is air that expanded and was forced out the test tube. It should, therefore, be discarded