I'm having alot of trouble in chemistry. Currently were studying chemical equations and reactions. I would like to know if this is a single or double replacement reaction.

2Li + H2O ---> 2LiOH + H2

That would consider to be a single replacement.

To determine if a chemical equation is a single or double replacement reaction, you need to understand the basic principles of these types of reactions.

In a single replacement reaction, also known as a single displacement reaction, one element is replaced by another element in a compound. A general single replacement reaction can be represented as:

A + BC --> AC + B

In a double replacement reaction, also known as a double displacement reaction, the positive ions and negative ions of two compounds switch places. A general double replacement reaction can be represented as:

AB + CD --> AD + CB

Looking at the given equation: 2Li + H2O -> 2LiOH + H2

We can see that lithium (Li) is reacting with water (H2O) to form lithium hydroxide (LiOH) and hydrogen gas (H2). From this, we can determine that the hydrogen atoms from water are replaced by lithium to form lithium hydroxide, and the lithium atoms are replaced by hydrogen to form hydrogen gas.

Since one element (hydrogen) is replaced by another element (lithium) in the compound (water), this is a single replacement reaction. Therefore, the given chemical equation can be classified as a single replacement reaction.