Posted by TJ on .
Which two solutions, when mixed together, will undergo a double replacement reaction and form a white, solid substance?
1. NaCl(aq) and LiNO3(aq)
2. KCl(aq) and AgNO3(aq)
3. KCl(aq) and LiCL(aq)
4. NaNO3(aq) and AgNO3(aq)
I know the answers 2 but I have no idea why.. thanks.
You need to know (and remember) the solubility rules and a couple of other points.
In general, reactions occur for one of three reasons.
a. a gas is formed. Do you know the common gases?
b. a precipitate (and insoluble material) is formed. Do you know the solubility rules?
c. a slightly ionized material is formed. Do you know the weak acids, weak bases, and any other weak electrolytes.
In this question, 2 is the answer because AgCl is formed and that is a white ppt. (rule b in the list of three above). Here is a site that gives the solubility rules.
I can help, also, if you don't know a or c in the list above. Let me know.
A little beyond what we're learning yet it still helped.. thank you !
Could you by any chance give me a list of gasses at STP?
Elements: Look at the periodic table to see where these are located.
rare gases (He, Ne, Ar, Kr, Xe, Rn) but these are rarely produced in CHEMICAL reactions.
carbon dioxide, CO2
carbon monoxide, CO
sulfur dioxide, SO2
sulfur trioxide, SO3
nitric oxide, NO
nitrous oxide, N2O
nitrogen dioxide, NO2
nitrogen pentoxide, N2O5
nitrogen trioxide, N2O3
ozone, O3 (technically not a compound)
fuels such as methane, ethane, acetylene, etc.
I see I didn't name by the new rules; i.e., N2O would be dinitrogen monoxide and N2O3 would be dinitrogen trioxide.
For rule c I gave you in the last post, weak acids and weak bases will have an ionization constant (Ka or Kb) and those will be listed in tables. If they are not listed in the Ka or Kb tables they are strong acids or bases. It is easier to list the strong ones. HCl, HBr, HI, H2SO4, HNO3, HClO4, HClO3, are the common strong acids. Common soluble strong bases are KOH, NaOH, (all group IA hydroxides) and Ca(OH)2, Ba(OH)2, Sr(OH)2. MOST others are weak.
Add water to the list of weak electrolytes above. It won't be listed in the Ka or Kb tables but it only weakly ionized.
I hope this gets you one jump ahead.
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