Gameobject to fade out on collision and fade in into another gameobject

Hello,I'm making a game for school project and I'm having issues with having the gameobject to fade out from Alpha 255 to Alpha 0 back to Alpha 255 but with a different object. Here's the scenario. Circle A touches Cube A Circle A gets destroyed and spawns Circle B,and the control is passed on to Circle B. But I would this whole process to have a transition. So Circle A touches Cube A, fades from alpha 255 to Alpha 0 then a few seconds later go from Alpha 0 to 255 for Circle B.

Here's my codes for reference.

[code=CSharp] public class Rotatela : MonoBehaviour { public float moveSpeed; public Rigidbody2D rb; public GameObject object1,object2;

 // Use this for initialization
 void Start () {
  
 }
 
 // Update is called once per frame
 void Update()
 {
     if (Input.GetAxisRaw("Horizontal") > 0)
     {
         rb.velocity = new Vector2(moveSpeed, rb.velocity.y); //Move to the right
         transform.localScale = new Vector3(1.0f, 1.0f, 1.0f);// Make sure when moving right, face right.
     }
     else if (Input.GetAxisRaw("Horizontal") < 0)
     {
         rb.velocity = new Vector2(-moveSpeed, rb.velocity.y); //Move to the left
         transform.localScale = new Vector3(-1.0f, 1.0f, 1.0f);// Make sure when moving left, face left.
     }
  
 }
 
 void OnCollisionEnter2D(Collision2D col)
 {

     if (col.gameObject.tag == "CubeS")
     {
         Instantiate(object2 , transform.position, transform.rotation);
         Debug.Log ("object2");
         Destroy(gameObject);
     }

 }

}[/code]