Answer: The 2 shows the number of potassium ions present in the compound, and the 2 is needed to show that 2 potassiums are needed to balance the charge on the sulphur ion. Suppose, then, that you wanted to write the formula for the ionic compound, magnesium chloride. Suppose you knew that magnesium ions had a 2+ charge, Mg 2+ , and chloride ions had a 1- charge, Cl - . Learn vocabulary, terms, and more with flashcards, games, and other study tools. With excess sulfur polysulfides can be formed- these contain Sn2- ions. My schoolwork asked me the following questions and I don't know how to answer them. You know you have the correct formula for an ionic compound when the positive and negative charges on the ions are the same or "cancel each other out." CHM 151 Plautz Equation Balance Final Exam Spring 2012 This chemical formula says that there are one magnesium ion and two chloride ions in this formula. Determine which compounds are aqueous and which compound will … This is what my school work said: Answer the following questions regarding the reaction of mercury(II) chloride with potassium sulfide: Valences Hg=+2 Cl=-1 K=+1 S=-2 Write the balanced ionic equation. The magnesium chloride has to be electrically neutral overall. Simple Ionic Formulas Nmne: _____ __ + 1. sodium iodide 2. sodium chloride 3. potassium hydride 4. potassium bronlide 5. silver oxide 6. zinc oxide 7. zinc nitride 8. silver sulfide 9. lithium nitride 10. potassium Hey! Write the ionic equation. Answer explained : So, if we look Determining the Formula of an Ionic Compound A stable ionic compound is electrically neutral, where electrons are shared between cations and anions to complete outer electron shells or octets. We could write the chemical formula for this ionic compound as MgClCl, but the convention is to use a numerical subscript when there is more than one ion of a given type—MgCl 2. Sial-12665; Potassium (poly)sulfide >=42% K2S basis; CAS Number: 37199-66-9; Linear Formula: K2S/n; find related products, papers, technical documents, MSDS & more at Sigma-Aldrich. How to Write the Formula for CaS (Calcium sulfide) - Duration: 1:04. Start studying Ionic Compound Formulas. Potassium and sulfur react to give K2S potassium sulfide, an ionic compound.