Unconfirmed transaction, cannot see money in receiving account

Question

I sent 0.6 bitcoin from my coinbase account to my blockchain account. The money doesn't show up in my blockchain account and shows as pending on my coinbase account with 0 confirmations. It has been about 2.5 hours. I'm a little worried because blockchain changes the wallet id for each transaction, and I never requested the money but just scanned the QR code from my iphone. Am I just being paranoid?

Miners fee was 0.00115, or about $5

What happens if it never gets confirmed or that address is no longer valid?

Answer 1

Barring chain reorganizations, valid transactions are binary: either they are confirmed, then your money has been signed over to the recipient, or they are yet unconfirmed and your funds are still unspent.

A transaction can remain valid but unconfirmed indefinitely, if the miners never chose it for block inclusion. Most wallets have a mechanism to forget unconfirmed transactions in order to be able to spend the funds elsewhere. When any of the funds used for the original transaction are used, the original transaction ceases to be valid.

Addresses do not become invalid after some time, and generally services keep records to associate addresses with the corresponding users even if an address didn't get used for a long time after it was generated.

For more general information on how to deal with unconfirmed transactions, please see: Why is my transaction not getting confirmed and what can I do about it?