It is an exothermic reaction
Answer: Fe<em>(aq)</em>+S<em>(aq)</em>=FeS<em>(s)</em>
Explanation: The Sodium and Bromine are spectator ions because they don't react with anything, you can see this by writing the ionic equation like so:
1.) Molecular formula (given): FeBr2 (aq)+Na2S (aq)= FeS(s)+2NaBr(aq)
Each dissolved FeBr2 breaks up into one Fe with a charge of 2+ and two Br with a negative charge. This gives you:
Fe(aq)+ 2Br(aq)+Na2S(aq)=FeS(s)+2NaBr
2.) Now repeat what was shown with the other compounds in the given molecular formula, and pay attention to the states that each ion is in (solid, liquid, aqueous, gas) because this will give you the ionic equation, which from there you can get rid of any ions that don't change amount or state.
3.) Ionic formula: Fe(aq)+ <u>2Br(aq)</u>+<u>2 Na(aq)</u>+S (aq)=FeS(s)+<u>2 Na(aq)+2Br(aq)</u>
4.)When you've derived a total ionic equation (above), you'll find that some ions appear on both sides of the equation in equal numbers. For example, in this case two Na cations and two Br anions appear on both sides of the total ionic equation. What does this mean? It means these ions don't participate in the chemical reaction. They're present before and after the reaction. Nothing happens to them. So those are removed and you're left with the net ionic: Fe(aq)+S(aq)=FeS(s)
Hope this helps :)
After 3 half-lives, 125 grams of the parent isotope will remain.
2Mg+ O₂= 2MgO
The charge of Mg is+2 and the charge of Oxygen is -2. 2 oxygen atoms will have a charge of -4 so the Mg atoms have to equal +4. A coefficient of 2 for the Mg atoms will balance it out
