Question

Which of the following are signs that a double displacement reaction has occurred? Choose all that apply.

		Solution changes color
		Solid precipitates out of solution
		Heat is emitted
		Mass is gained
		Gas formation
		Water formation

Answer 1

Double displacement reaction occurs when the cationic and anionic parts of compounds are exchanged resulting in the formation of new compound .

For example

BaCl₂(aq) + Na₂SO₄(aq) --> BaSO₄(s) + 2NaCl(aq)

So generally precipitation and neutralization reactions are considered to be double displacement reaction because these reactions results from the exchange of ionic species.

Now to know whether double displacement reaction has occurred the signs are

1.Solid precipitates out of the solution like in precipitation reactions.

2.water formation like in neutralization reaction

3. Also colour is changed during precipitation reaction which can be a sign of double displacament reaction as well.

so options 1 ,2 and 6 are correct