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Chemistry 17 Online
OpenStudy (roku):

is there a difference or is there something wrong with writing the equation like this: 2 Ca(s) + 2 H2O(l) = 2CaOH(aq) + H2(g) instead of like this: Ca(s) + 2 H2O(l) = Ca(OH)2(aq) +H2(g)

OpenStudy (preetha):

Roku the formula on Ca(OH)2 is wrong in the first version. You have it right in the second version. Otherwise I don't see a difference.

OpenStudy (vincent-lyon.fr):

More simply, the first reaction does not exist because Ca(OH) is not a known substance.

OpenStudy (roku):

thanks @Vincent-Lyon.Fr

OpenStudy (vincent-lyon.fr):

Welcome :)

OpenStudy (roku):

so how can i know weather or not something exists like that or not... cause im having trouble like this in other equation i write.

OpenStudy (vincent-lyon.fr):

Calcium is an element in the second group of the periodic table. It will have only one stable ion which is Ca2+, as it will lose its last 2 electrons and have stable state as argon. OH- has only one extra negative charge. In order to have a neutral compound, you need 2 hydroxide ions for each calcium ion, hence the formula Ca(OH)2. If you work with potassium instead, which is in group 1, then ion is K+ and potassium hydroxide is KOH

OpenStudy (roku):

these are all ionic bonding right?

OpenStudy (vincent-lyon.fr):

Yes they are. Actually, OH- being a polyatomic anion has a covalent bond between O and H too. What we wrote would hold for CaCl2 and KCl with anion Cl- which is monatomic.

OpenStudy (roku):

so the only way to seperate these two reactions again would be by electolysis. why is OH covalent?

OpenStudy (vincent-lyon.fr):

What do you mean "separate"? Electrolysis is not just separating Ca2+ and Cl- (as in 'bringing them apart'), it would actually change their chemical nature by oxidizing one and reducing the other.

OpenStudy (roku):

i still dont quite understand oxidizing and reduction i just know oxidizing is the add of oxygen and removal of hydrogen while reduction is the opposite of the oxidation.

OpenStudy (vincent-lyon.fr):

Actually adding electrons is also reduction: \(Ca^{2+}+2e^-\rightarrow Ca \) Removing electrons is oxidation: \( Cl^- \rightarrow Cl+e^-\)

OpenStudy (roku):

electrolisys cause ions to form back into their element isnt that just about accurate?

OpenStudy (vincent-lyon.fr):

It is not always the case, but it is mostly used to achieve what you say.

OpenStudy (vincent-lyon.fr):

For instance, in aqueous solution, you cannot perform: \( Na^+ + e^-\rightarrow Na\) because Na+ is too difficult to reduce and water gets reduced instead.

OpenStudy (roku):

my mind is still a bit slow in processing this but ok thanks @Vincent-Lyon.Fr

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