Need Help with Chemistry (1 Viewer)

HiHaii

Member
Joined
Aug 16, 2009
Messages
63
Location
Campsie
Gender
Male
HSC
2011
lol a good discussion u guys are having
I mean writing as a compound as in having the brackets in each of the elements
it's hard to illustrate it here but it goes something like:
[O][2Br] then you have the dots around each of the element according to the valency as well as the symbol, such and such
 
Joined
Dec 31, 2009
Messages
4,741
Location
sarajevo
Gender
Female
HSC
2015
Uni Grad
2017
lol a good discussion u guys are having
I mean writing as a compound as in having the brackets in each of the elements
it's hard to illustrate it here but it goes something like:
[O][2Br] then you have the dots around each of the element according to the valency as well as the symbol, such and such
You do that for ionic compounds, OBr2 is a covalent compound.
 

adomad

HSC!!
Joined
Oct 10, 2008
Messages
543
Gender
Male
HSC
2010
you put the brackets with ions... with the diagram above, the charge of the ions should be displayed
 

HiHaii

Member
Joined
Aug 16, 2009
Messages
63
Location
Campsie
Gender
Male
HSC
2011
It seems like I keep on asking for more help...

1)Some fertilisers are labelled "NPK fertiliser" because they contain the elements nitrogen, phosphorus and potassium. Which of the following pairs of compounds could be used as a "NPK fertiliser"?
A) ammonia and sodium hydrogen phosphate
B) ammonium phosphate and calcium sulfate
C) calcium phosphate and potassium nitrate
D) potassium hydrogen phosphate and calcium sulfate

the answer is C but I'm not sure why...please explain

2) A red powder is placed in a test tube, water is added and the contents are then filtered. A brown solid is left on the filter paper. After evaporating the filtrate, white crystals are left. This analysis suggest:
a) the red powder is a mixture
b) the brown solid is an element
c) the white crystals are a mixture
d) the red powder is a compound

a?

3) Atom X has two electrons in it's outer shell while atom Y has seven. The chemical formula of the compound formed from X and Y would be:
a) X^2Y^6
b) X^2Y
c) X^2Y^2
d) XY^2

4) identify the group in which all of the substances have covalent bonds:
a) diamond, graphite, carbon dioxide, potassium fluoride
b) hydrogen iodide, water, calcium chloride, paraffin wax
c) iodine, ice, zinc sulfide, ethanol
d) ammonia, oxygen, water, methane
 

x jiim

zimbardooo.
Joined
Jul 10, 2008
Messages
477
Gender
Female
HSC
2010
Uni Grad
2018
It seems like I keep on asking for more help...

1)Some fertilisers are labelled "NPK fertiliser" because they contain the elements nitrogen, phosphorus and potassium. Which of the following pairs of compounds could be used as a "NPK fertiliser"?
A) ammonia and sodium hydrogen phosphate
B) ammonium phosphate and calcium sulfate
C) calcium phosphate and potassium nitrate
D) potassium hydrogen phosphate and calcium sulfate

the answer is C but I'm not sure why...please explain

2) A red powder is placed in a test tube, water is added and the contents are then filtered. A brown solid is left on the filter paper. After evaporating the filtrate, white crystals are left. This analysis suggest:
a) the red powder is a mixture
b) the brown solid is an element
c) the white crystals are a mixture
d) the red powder is a compound

a?

3) Atom X has two electrons in it's outer shell while atom Y has seven. The chemical formula of the compound formed from X and Y would be:
a) X^2Y^6
b) X^2Y
c) X^2Y^2
d) XY^2

4) identify the group in which all of the substances have covalent bonds:
a) diamond, graphite, carbon dioxide, potassium fluoride
b) hydrogen iodide, water, calcium chloride, paraffin wax
c) iodine, ice, zinc sulfide, ethanol
d) ammonia, oxygen, water, methane
1C, because calcium phosphate contains P [phosphate is PO4, charge 3-], and there's K and N in the potassium nitrate [KNO3]
2A, yes.
3D because each X needs to donate 2electons and each Y needs to gain one.
4D, as potassium fluoride, calcium chloride and zinc sulfide are ionic compounds.
 
Last edited:
Joined
Dec 31, 2009
Messages
4,741
Location
sarajevo
Gender
Female
HSC
2015
Uni Grad
2017
1c, because calcium phosphate contains p [phosphate is po4, charge 3-], and there's k and n in the potassium nitrate [kno3]
2a, yes.
3d because each x needs to donate 2electons and each y needs to gain one.
4d, as potassium fluoride, calcium chloride and zinc sulfide are ionic compounds.
+1
 

HiHaii

Member
Joined
Aug 16, 2009
Messages
63
Location
Campsie
Gender
Male
HSC
2011
please help with this question, i am having trouble knowing how cause it's hard

how do i find the empirical formula of the minerals Boehmite, Gibbsite and Diaspore?
Given that the composition of:
Boehmite is 44.98% Al, 53.34% O, 1.68% H (Density: 3.1, Hardness: 3)
Gibbsite is 34.59% Al, 61.54% O, 3.88% H (Density: 2.4, Hardness: 2.5-3.5)
Diaspore is 44.98% Al, 53.34% O, 1.68% H (Density: 3.3-3.5, Hardness 6.5-7)
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top