Today, my science teacher did some experiments of reacting different metals, like the alkali and alkaline metals with water. Afterwards, we got some questions. This one stumped me. When calcium reacts with water, what gas is produced and how do you know? The next one is the same questions except replace calcium with lithium. Some help please? :)

Well... if all you have is a metal and water the reaction converts the metal to the ionized form by loss of electrons and produces calcium hydroxide and hydrogen gas.

Ca + 2 H2O ---> Ca(OH)2 + H2

You need 2 waters... the ca becomes Ca2+ when it ionizes, the water provides HO-... so need 2 HO- to offset the charge of the calcium.

Only diff with lithium is it is one more column to the left on the periodic table, correct? So what does lithium ionize to? Li+? Li2+? Li3+? Figure this out and then you'll need one hydroxide per +

If you really don't know you need to look in your book. There should be a section on naming common ions. Also may be covered in periodic table discussion.

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Originally Posted by angelchild_

Today, my science teacher did some experiments of reacting different metals, like the alkali and alkaline metals with water. Afterwards, we got some questions. This one stumped me. When calcium reacts with water, what gas is produced and how do you know? The next one is the same questions except replace calcium with lithium. some help please? :)

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Thanks for the help :)