CH4 + Cl2 → CH4Cl + HCl

Is this a double replacement reaction? I believe it is but am not entirely sure.

To extend the answer from Damon, you probably meant CH3Cl + HCl. This is not a double replacement reaction. It is a redox reaction. In some organic circles this is called a substitution reaction; i.e., you're substituting a Cl atom for a H atom.

No, this is not a double replacement reaction.

A double replacement reaction, also known as a metathesis reaction, involves the exchange of ions between two compounds, resulting in the formation of two new compounds. In a double replacement reaction, the cations and anions of the reactant compounds switch places to form new compounds.

In the given reaction:

CH4 + Cl2 → CH4Cl + HCl,

we can see that there is no exchange of ions or switching of cations and anions. Instead, the reactants methane (CH4) and chlorine (Cl2) combine to form chloromethane (CH4Cl) and hydrogen chloride (HCl). This type of reaction is known as a synthesis reaction or a combination reaction, where two or more substances combine to form a single compound.

No, the given chemical equation is not a double replacement reaction. It is a single replacement reaction.

A double replacement reaction occurs when the positive ions from two different compounds exchange places with each other, resulting in the formation of two new compounds. In this type of reaction, the cations and anions switch partners.

On the other hand, a single replacement reaction occurs when an element reacts with a compound and displaces another element from it. In the given equation, methane (CH4) is reacting with chlorine gas (Cl2) to form methyl chloride (CH4Cl) and hydrogen chloride (HCl). The chlorine molecule is being replaced by hydrogen in the methane molecule, resulting in the formation of a new compound.

To determine if a chemical equation is a double replacement reaction, you need to check if the positive ions and negative ions in the reactants switch places to form new compounds. If they do, it is a double replacement reaction. If not, it is another type of reaction, such as a single replacement reaction in this case.

Well, first of all your reaction is not balanced

https://www.thoughtco.com/definition-of-double-replacement-reaction-605046

C+4 4H- ????
whoa!, No such ions
This is not an ionic bond. C and H share electrons to make the hydrocarbon CH4 methane