CHEM AND BIO HELP AND TIPS HERE

[Ghost Of Highbury]

how do you figure out the limiting reactant if the mole ratio is NOT 1:1          

Example : Mg + 2HCl --> MgCl2 + H2

If 0.1 mol of Mg reacts with 0.1 mol of HCl, the limiting reactant is HCl acid because, i we look at the equation, for every mole of Mg used we need 2 moles of HCl.

So there will still be 0.1/2 0.05 mol of Mg left when the HCl is used up.

[Liya]

can someone help me?
in june'08 chemistry p3 number 1.e
"name an element that has oxidation states of 2 and 3 only"
so, how do you find the answer for all questions like this one?

[Meticulous]

iron

[nid404]

Metal that have varying oxidation numbers are transition metal.
Fe-->2+/3+
Cu-->+/2+

etc...

[jellybeans]

Questionnnn , why do some elements react with water to form oxides but some hydroxides? 

[Ghost Of Highbury]

As a general rule, if a metal reacts with cold water, you get the metal hydroxide. If it reacts with steam, the metal oxide is formed. This is because the metal hydroxides thermally decompose (split up on heating) to give the oxide and water.

Though, there are some who dont form oxides at all, only hydroxides

[Ivo]

If someone could please answer my doubt, that would be greatly appreciated.

For the 2 diagrams attached, do both represent poly(but-1-ene)?

[nid404]

Yup both are fine

[username]

definitley no

because
1 has 4 carbons
and 1 has 3

met  1
eth  2
prop   3
but    4

[username]

YIKES!!!!

sry
didnt c the 2
yup
ur rite

[jellybeans]

As a general rule, if a metal reacts with cold water, you get the metal hydroxide. If it reacts with steam, the metal oxide is formed. This is because the metal hydroxides thermally decompose (split up on heating) to give the oxide and water.

Though, there are some who dont form oxides at all, only hydroxides

so lets say they give you a question liek

Both metals react with water
i) Write a word equation for the reaction of zinc and water and state the reaction conditions

ii) Write an equation for the reaction of strontium with water and give the reaction condition.
 

how do we know if it's gonna make oxides/hydroxides?

[nid404]

Both would form hydroxides in cold water.
Although Zinc would have a slower reaction since it's less reactive compared to Strontium.

[username]

wouldnt zinc be in steam???

[nid404]

wouldnt zinc be in steam???

It would form oxide with steam

[username]

wud this hav 2 do sumthin with the reactivity series???