Qualification > Sciences
chem question
Ghost Of Highbury:
u asked abt the colour change...
its important to use both the litmus papers...
if red litmus shows no change it means that it remains red which means its an acid
if blue litmus shows no change it means that it remains blue which means its an alkali
it cant be an acid and alkali together thus u can conclude that its a salt
Q80BOY:
ahaaa .. i get it .. thanks adii!! ;)
Ghost Of Highbury:
anytime dude...!!
Bani:
Hello guyss....here is what I need ur kind help again on : [c(ii)]
The main ore of lead is galena, lead(II) sulphide.
To produce lead, this ore is heated in air, when some of the lead(II) sulphide is converted to lead(II) oxide and sulphur dioxide.
The air supply is then cut off and on further heating the lead(II) oxide is converted, by reaction with the remaining lead(II) sulphide, to lead and sulphur dioxide.
Write an equation for (i) the conversion of galena to lead(II) oxide and (ii) the reaction of lead(II) oxide with lead(II) sulphide.
Answers:
(i) 2PbS + 3O2 ----> 2PbO + 2SO2
(ii) 2PbO + PbS ----> 3Pb + SO2
Qb) Calculate the total volume (m3) of sulphur dioxide which would be produced from 5.0 x 10^3 kg of galena in the reactions described in (a). (Assume that one mole of any gas occupies 2.4 x 10^-2 m3 at room temperature and pressure.) (3 marks.)
Answer: 1.004 m^3 ( not sure if its correct ; i did not convert the m^3 to cm^3, as the mass given is in kg...so i think its fine if we don't change the units..)
Qc)i) Another compound of lead, Z, which is found naturally contains 77.5% of lead and 4.5% of crbon by mass. The remainder being assumed to be oxygen. Calculate the empirical formula of the compound.
Answer: PbCO3 (not sure if its right.)
ii) 0.0500 mol of this compound Z gives, on heating, 11.2g of lead(II) oxide and a gas is evolved. What is the molecular formula of the compound Z?
idk how to solve this...
there are some more parts to this Q. i'll post la8er.
Thanks in advance..
nid404:
b) Combine the reactions
2PbS + 3O2 ----> 2PbO + 2SO2
2PbO + PbS ----> 3Pb + SO2
you get
3PbS+3O2--->3Pb+3SO2
ratio of sulphide to sulphur dioxide is 1:1
mass in 1 mole of lead sulphide=239.265
mass of lead sulphide used= 5x10^3 X1000g=5X10^6g
moles of lead sulphide=5x10^6/239.265
=20897.33moles
volume of sulphur dioxide=moles X 2.4X10^-2 =501.53 m3
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