A student 發問於 科學及數學化學 · 1 十年 前

Sodium hydroxide and Hydrochloric acid

I think I have misunderstood this...

Na + H2O -> NaOH + H+ ........is it correct??

HCl + H2O -> Cl- + H3O+ ............ is it correct?

How about when neutralise both of them by adding them to eachother. Please give me the ionic equation. More details in the equation will help me udnerstanding. PLEASE!

更新:

N70 thanks for continously helping me. So, if adding sodium into water is not the correct way, then what should be thr right 1? Many thx!

更新 2:

Does sodium hydroxide and hydrochloric acid has the same opposite pH value? For example 4 and 11 ?? Just an example. So is it all alkali and acid are made of group 1 and group 7 elements which are at the same period. Are they the same opposite pH value.

更新 3:

THanks for helping. 7 is the neutral pH value. So, if a weak acid + a strong alkali, or vice versa, it will not be neutralise? Is it a must that they have to be opposite? THX!!

更新 4:

I mean like an acid that has 2 ph value and it will be fulled neutralise by an alkali with 12 ph value?

2 個解答

評分
  • N70
    Lv 7
    1 十年 前
    最佳解答

    The equation for sodium + water is wrong and should be :

    Na (s) + H2O (l) => NaOH (aq) + H2 (g)

    It is a highly exothermic and violent reaction, resulting in self-ignition of the hydrogen gas so produced. It is NOT the proper way to produce sodium hydroxide.

    The equation for HCl is a correct illustration of the ionization of HCl in water. But for simplicity, we usually just write H+ instead of H3O+ when writing ionic equations.

    The equation for neutralization between NaOH and HCl is:

    HCl (aq) + NaOH (aq) => NaCl (aq) + H2O (l)

    Ionic equation is:

    H+ (aq) + OH- (aq) => H2O (l)

    2007-09-30 20:05:06 補充:

    NaOH is produced by electrolysis of sodium chloride solution.

    2007-09-30 20:36:43 補充:

    Actually, the opposite of acid should be BASE. Under the Brønsted-Lowry theory, acid is a proton (i.e. H ion) donor while base is a proton acceptor (refer to your books for other definitions). Alkalis are solutions of bases e.g. NaOH, KOH solutions are alkalis.

    2007-09-30 20:37:06 補充:

    All acids have pH lower than 7 when dissolved in water while all alkalis have pH more than 7. pH value is determined by the concentration of H ions in the solution which varies with:1. The concentration of the acid/alkali (e.g. conc. HCl will have a lower pH value than dilute HCl); and

    2007-09-30 20:37:21 補充:

    2. The degree of ionization of the acid/alkali (e.g. HCl completely ionized in water to give H ions while hydrofluoric acid only partly ionized. So for the same concentration, HCl will have a lower pH value than HF)

    2007-09-30 20:37:32 補充:

    You cannot predict the pH value of an acid/alkali from its compositing ions or the group of element which the ions belong to. e.g. fluorine and chlorine are both Group 7 elements but the same concentration of hydrofluoric acid and hydrochloric acid have different pH.

  • 1 十年 前

    If you just adding in water in different chemicals,no reaction will occur,the solution is just diluted by water.

    The above equation is incorrect. As I never learn this type of reaction and my teacher told me that adding in water is just for diluting the concentration of the solution.

    If you add sodium hydroxide into hydrochloric acid, the equation will be:

    NaOH(aq) + HCl(aq) → NaCl(aq) + H2O (l)

    ionic equation:

    OH-(aq) + H+(aq) → H2O(l)

    As the state of Na and Cl do not change (still aq), we can ignore them in the ionic equation.

    Just write down the chenicals which change its state.

    For example:

    Reaction: CaCO3(s) + 2HCl(aq) → CaCl2(aq) + CO2(g) + H2O(l)

    Ionic equation: CaCO3(s) + 2H+(aq) → Ca2+(aq) + CO2(g) + H2O(l)

    State of Cl is unchage,so we can delete it from the ionic equation.

    Ca changed from (s) to (aq), CO3 changed from (s) to (g) and 1 O is uesd to form H2O which H is changed from (aq) to (l).

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