Answer: With atomic number 20, calcium atoms have 20 positive protons, and the ion has only 18 electrons, which means the net charge is +2. Calcium ions are essential for muscle contractions, nerve impulses, and bone maintenance.
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1. a. FeS + 2HCl --> FeCl2 + H2S
b. This is a double- replacement reaction. (The elements "switch partners".)
2. a.2Na + F2 --> 2NaF
b. This is a composition/synthesis reaction. (The two reactants are combining or synthesizing to make one product.)
3. a. 2HgO --> 2Hg + O2
b. This is a decomposition reaction. (The single reactant is breaking down or "decomposing" into multiple reactants.)
4. Hydrogen gas reacts with oxygen gas to create water in a composition/synthesis reaction.
I hope these answers will help you! If you need any explanation, ask and hopefully I can get back to you. ;)
A) Fe⁰ ----> Fe⁺³ +3e⁻ oxidation | *2
b) <u>Cu⁺² + 2e⁻ -----> Cu⁰ reduction |*3</u>
c) 2Fe⁰ +3Cu⁺² -----> 2Fe⁺³ + 2Cu⁰
