No, you just gave me the wrong answer.
Calvin does appeal to the justice of God as does Boettner.
I think you need to go reread you Calvin and stop wasting your time with light-weights like Sproul.
For what more seems to be said here than just that the power of God is such as cannot be hindered, so that he can do whatsoever he pleases? But it is far otherwise. For what stronger reason can be given than when we are ordered to reflect who God is? How could he who is the Judge of the world commit any unrighteousness? If it properly belongs to the nature of God to do judgment, he must naturally love justice and abhor injustice. Wherefore, the Apostle did not, as if he had been caught in a difficulty, have recourse to evasion; he only intimated that the procedure of divine justice is too high to be scanned by human measure, or comprehended by the feebleness of human intellect.
Thus, Calvin's ultimate appeal is not to mercy nor to even power, but to Justice.
So once again, why are some elected and some condemned?
All are equal, and you say that God in his mercy saved some and not others, what critera did He use if all were seen as the same?
The Justice of God is essential, because His Mercy is meaningless without the backdrop of Justice. Why do you have such a hard time with that? Calvin did not say God's choice of some sinners unto salvation was based on His Justice. Calvin said that God's Justice is righteous and Just, and therefore so are His Judgments. He's not talking about Election, he's talking about Judgment and Divine Justice in this quote.
What is the criteria God uses for selecting some sinners and not selecting others? He doesn't tell us specifically. Therefore, like it or not, it is a mystery unto us, but not to God. If it pleases Him to do so, He may reveal it to us in Glory, but it is not revealed in scripture.
Why do you insist that this criteria must be knowable, or known? Will you not accept salvation otherwise? At various times you have made the charge of arbitrariness, capriciousness, or whim as the basis of God's choice, according to Calvinists, which you know full well is a false statement. God had a reason, of that I have no doubt. But if he chooses not to reveal it, who am I (or you?) to get all huffy about it? Since when is He required to satisfy your curiosity? You certainly don't believe that God has revealed 100% of who He is, how He works, and what His reasons are for doing what He does, do you?
That which is not revealed is by definition a mystery, something which belongs to the secret counsel of the Most High. But the mere mention of such a concept sends you into a Calvinist-bashing tirade. You won't even let God be God! You demand that He reveal whatever you want to know, RIGHT NOW! And when He doesn't, then you say, "aha!! I knew it was mysticism all along. Because of that, it CAN'T be True!"