Chapter 18.3, Problem 20R

To determine

The formulas for the given compounds.

Answer to Problem 20R

The formulas for the compounds potassium iodide, phosphorus pentachloride, magnesium hydroxide, aluminum sulfate, dichlorine heltoxide and calcium nitrate trihydrate are KI, ${\text{PCl}}_{\text{5}}$ , $\text{Mg}{\left(\text{OH}\right)}_{\text{2}}$ , ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{SO}}_{\text{4}}$ , ${\text{Cl}}_{\text{2}}{\text{O}}_{\text{7}}$ and $\text{Ca}\left({\text{NO}}_{\text{3}}\right){\text{.3H}}_{\text{2}}\text{O}$ .

Explanation of Solution

Given:

The compounds are potassium iodide, phosphorus pentachoride, magnesium hydroxide, aluminum sulfate, dichlorine heltoxide and calcium nitrate trihydrate.

Calculation:

The combination of two or more elements is called a compound.

In potassium iodide, the negative ion is iodine and the positive atom is potassium. The charge on the potassium is +1 and on iodide is -1.

Therefore, the formula for potassium iodide is KI.

In phosphorus pentachoride, the negative ion is chlorine and the positive atom is Phosphorous. The charge on Phosphorous is +5 and on chlorine is -1.

Therefore, the formula for phosphorus pentachoride is ${\text{PCl}}_{\text{5}}$ .

In magnesium hydroxide, the negative ion is hydroxide and the positive atom is magnesium. The charge on magnesium is +2 and on hydroxide is -2.

Therefore, the formula is $\text{Mg}{\left(\text{OH}\right)}_{\text{2}}$ .

In ammonium sulfate, the negative ion is sulfate and the positive atom is ammonium. The charge on ammonium is -2 and on sulfate is +2.

Therefore, the formula is ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{SO}}_{\text{4}}$ .

In dichlorine heptoxide, the negative ion is heptoxide and the positive atom is chlorine. The charge on heptoxide is -7 and on chorine is +7.

Therefore, the formula is ${\text{Cl}}_{\text{2}}{\text{O}}_{\text{7}}$ .

In calcium nitrate trihydrate, the negative ion is nitrate and the positive atom is calcium. The charge on nitrate is -2 and on calcium is +2.

Therefore, the formula is $\text{Ca}\left({\text{NO}}_{\text{3}}\right){\text{.3H}}_{\text{2}}\text{O}$ .

Conclusion:

Hence, the formulas for the compounds potassium iodide, phosphorus pentachoride, magnesium hydroxide, aluminum sulfate, dichlorine heltoxide and calcium nitrate trihydrate are KI, ${\text{PCl}}_{\text{5}}$ , $\text{Mg}{\left(\text{OH}\right)}_{\text{2}}$ , ${\left({\text{NH}}_{\text{4}}\right)}_{\text{2}}{\text{SO}}_{\text{4}}$ , ${\text{Cl}}_{\text{2}}{\text{O}}_{\text{7}}$ and $\text{Ca}\left({\text{NO}}_{\text{3}}\right){\text{.3H}}_{\text{2}}\text{O}$ .