# Write and balance the following word reactions, and state if a precipitate is formed? Barium cyanide reacts with ammonium sulfate. Potassium hydroxide reacts with magnesium chloride.

##### 1 Answer
Jul 6, 2017

These are regular double-replacement reactions, of the form

$A B + C D \to A D + C B$.

Basically, the cations switch, and charge is considered when determining the number of anions per cation / cations per anion. What is the formed solid called?

So, you should get:

color(blue)(stackrel(color(red)(2+))"Ba"(stackrel(color(red)(1-))"CN")_2(aq) + (stackrel(color(red)(1+))("NH"_4))_2stackrel(color(red)(2-))("SO"_4)(aq) -> 2stackrel(color(red)(1+))("NH"_4)stackrel(color(red)(1-))("CN")(aq) + stackrel(color(red)(2+))"Ba"stackrel(color(red)(2-))("SO"_4)(s))

Is this balanced? If not, you should fix it up.

• Barium cyanide is reasonably soluble in water ($\text{18 g/100 mL water}$ at ${25}^{\circ} \text{C}$).

• Barium sulfate is very poorly soluble (as we would expect from the guideline that sulfates are soluble except for those with ${\text{Ag}}^{+}$, ${\text{Pb}}^{2 +}$, ${\text{Ca}}^{2 +}$, ${\text{Sr}}^{2 +}$, or ${\text{Ba}}^{2 +}$ cations).

• All ammonium-based compounds are very soluble.

color(blue)(2stackrel(color(red)(1+))"K"stackrel(color(red)(1-))"OH"(aq) + stackrel(color(red)(2+))"Mg"stackrel(color(red)(1-))("Cl"_2)(aq) -> 2stackrel(color(red)(1+))"K"stackrel(color(red)(1-))"Cl"(aq) + stackrel(color(red)(2+))"Mg"(stackrel(color(red)(1-))"OH")_2(s))

Is this balanced? If not, you should fix it up.

• All alkali-metal-based compounds are quite soluble in water.
• Halides are as well (except for those with ${\text{Hg}}_{2}^{2 +}$, ${\text{Ag}}^{+}$, or ${\text{Pb}}^{2 +}$ cations).
• Hydroxides tend to be insoluble, and "Mg"("OH")_2 is no exception ($\text{0.00064 g/100 mL water}$ at ${25}^{\circ} \text{C}$).