chemistry questions

[izzahzainab]

1.Ethanoic acid is a weak acid. It reacts with magnesium giving a gas and a magnesium
salt. What is the formula of the magnesium salt formed?

2.Nitrogenous fertilisers are used to increase crop yield. Potassium nitrate, KNO3, and ammonium
sulphate, (NH4)2SO4, are two nitrogenous fertilisers.
(a) Which fertiliser, potassium nitrate or ammonium sulphate contains the greater percentage
mass of nitrogen? Explain your answer. [3] (i couldnt get the answers right)

3. suggest a source of unburnt hydrocarbons. (i dont think it can be "car engines" because the hydrocarbons there are "incompletely burnt", not "unburnt". is vegetative decay correct answer (CH4)?? ewxaminer report says "car engines" is correct)

 

[OakMoon!]

1. Magnesium Ethanoate. Mg(CH3COO)2. The hydrogen atom is removed.
2. You can easily take out the percentage by using Ar of all the atoms involved.
Potassium Nitrate. Nitrogen's Mr= 14. Total Mr=19+14+16*3=81 Percentage=14/81*100=17.28%
Ammonium Sulphate. Nitrogen's Mr=14*2=28. Total Mr=18*2+32+16*4=132. Percentage of N=28/132*100=21.2% So ammonium sulphate is the answer.
3. Car engines is absolutely correct. Incompletely burnt includes those carbons that are left unburnt. The question doesn't says to tell a source in which all of the hydrocarbons used goes unburnt but a source of it. Car engines do leave some of the carbon unburnt which makes it a source.

 

[insomniac]

its perfectly answered .. =)

 

[CaptainDanger]

Potassium ka 39 nahin hai?????

 

[VelaneDeBeaute]

Well Hamidali,
dnt u think for the percentage question, the Mr of KMnO4 is 39+14+3*16=101. Then the percentage cumz out 2 b 14/101*100=13.7%.Isnt the mass nbr of Potassium 39..??

 

[CaptainDanger]

Well Hamidali,
dnt u think for the percentage question, the Mr of KMnO4 is 39+14+3*16=101. Then the percentage cumz out 2 b 14/101*100=13.7%.Isnt the mass nbr of Potassium 39..??

He is not talking about Potassium permanganate here... Its KNO3... You are right he mistakenly got that wrong... Potassium's mass 39... Not 19... But still his answer is correct...

 

[OakMoon!]

Yes. My mistake, I used the atomic number instead. :S Thankyou galya for informing.

 

[CaptainDanger]

No problem... Galya means?????

 

[leosco1995]

Galya is his/her name.

Also yeah the percentage is 13.7.

 

[CaptainDanger]

Oh okay...lol

 

[VelaneDeBeaute]

My pleasure that u guys took my notice..
anywayz why r u leaving out the H in my name.....4 tymz u consistently wrote my name widout an H..!! :lol:

 

[CaptainDanger]

Ops! Hamid had written Galya... I copy pasted... Didn't know at that time what it was...

 

[VelaneDeBeaute]

Ah well its okay..
but u guys changed the meaning

 

[CaptainDanger]

Lol....