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好多chem唔識.救命!! 我就drop得啦...~.~
1.pure acid and acid are different ? why they're different ?
2.calcium sulphate + lead nitrate . What will be formed ?
is the above is displacement reaction? if yes , can u teach me how to change ?( i only know like sodium sulphate + lead will form lead sulphate + sodium )
3.when sodium hydroxide added to lead(ll)nitrate. write down all observation(s).
thanks alot ~
4 個解答
- Man OnLv 41 十年前最愛解答
1. Pure acid and acid are different.
Pure acid means there is no any water in the acid. If the acid doesn't dissolve into the water, it doesn't contain H+ . However, if the aicd dissolve into the water, it ionizes and products H+.
2. Calcium sulphate + Lead nitrate will form nothing.
Because calcium sulphate cannot dissolve into the water and product any ions to occur precipitation reaction.
Furthermore, there is no reaction between sodium sulphate and lead.
Because sodium is more reactive than lead. So, sodium ion is not be reduced by lead!
Moreover, if there is a reaction between two salt solution, it is not a
displacement reaction. Because no any ions was given any electrons.
3. After Add little sodium hydroxide, the solution appears some white precipitate and
products heat.
If the solution was added excess of sodium hydrocide, it changes to a colorless
solution and produces heat.
Don't drop "Chemistry" ! Which is a very interesting subject! You can get many marks from Chemistry in HKCEE or the other examination!
- 香港早晨Lv 71 十年前
Yea, I agree with you in large extent.
You only need memorize and calculation in this subject.
But if you are in F.5 and still don't know things taught in F.3, then drop it!
- 1 十年前
1.唔係太肯定
好似pure acid=溶落水totally dissolves
acid=溶落水未必totally dissolves
2.Ca(SO4)(aq)+Pb(NO3)2(aq)--->PbSO4(s)+Ca(NO3)2(aq)
唔知係未displacement reaction bo
3.heat given out(9成萬用)
salt are formed(acid+alkali)
water formed(acid+alkali)
