Mercy and Grace

One thing that took me a while to tell the difference between is mercy and grace. I always thought that they where synonyms, but they sure are not.
So first, I'll start with mercy. If you show mercy, then you're NOT doing what someone deserves.
Now I'll do grace. If you show grace, then your're doing MORE what someone deserves.

God saved us by grace and through mercy.

For it is by grace you have been saved
Ephesians 2:8a

He saved us, not because of righteous things we had done, but because of his mercy.
Titus 3:5a

Here is one of the only verses that is about both grace and mercy.

Let us then approach the throne of grace with confidence, so that we may receive mercy and find grace to help us in our time of need.
Hebrews 4:16

In the case of salvation, God has to show us both mercy AND grace. Mercy because, as Christians, we are not going to hell. And grace because, as Christians, we are going to heaven.
And, even after that, God shows grace by blessing us and mercy by forgiving us

But in your great mercy you did not put an end to them or abandon them, for you are a gracious and merciful God.
Nehemiah 9:31

The LORD is compassionate and gracious, slow to anger, abounding in love.
Psalms 103:8

What then shall we say? Is God unjust? Not at all! For he says to Moses, "I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion." It does not, therefore, depend on man's desire or effort, but on God's mercy. For the Scripture says to Pharaoh: "I raised you up for this very purpose, that I might display my power in you and that my name might be proclaimed in all the earth." Therefore God has mercy on whom he wants to have mercy, and he hardens whom he wants to harden. One of you will say to me: "Then why does God still blame us? For who resists his will?" But who are you, O man, to talk back to God? "Shall what is formed say to him who formed it, 'Why did you make me like this?'" Does not the potter have the right to make out of the same lump of clay some pottery for noble purposes and some for common use?
Romans 9:14-21

God made us. God is free to be gracious and merciful.

"Woe to him who quarrels with his Maker, to him who is but a potsherd among the potsherds on the ground. Does the clay say to the potter, 'What are you making?' Does your work say, 'He has no hands'?
Isaiah 45:9

Woe to those who go to great depths to hide their plans from the LORD, who do their work in darkness and think, "Who sees us? Who will know?" You turn things upside down, as if the potter were thought to be like the clay! Shall what is formed say to him who formed it, "He did not make me"? Can the pot say of the potter, "He knows nothing"?
Isaiah 29:15-16

Speak and act as those who are going to be judged by the law that gives freedom, because judgment without mercy will be shown to anyone who has not been merciful. Mercy triumphs over judgment!
James 2:12-13

Keep yourselves in God's love as you wait for the mercy of our Lord Jesus Christ to bring you to eternal life.
Jude 1:21

Titus 3:1-11

Remind the people to be subject to rulers and authorities, to be obedient, to be ready to do whatever is good,
to slander no one, to be peaceable and considerate, and to show true humility toward all men.
At one time we too were foolish, disobedient, deceived and enslaved by all kinds of passions and pleasures. We lived in malice and envy, being hated and hating one another. 
But when the kindness and love of God our Savior appeared,
he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit,
whom he poured out on us generously through Jesus Christ our Savior,
so that, having been justified by his grace, we might become heirs having the hope of eternal life.
This is a trustworthy saying. And I want you to stress these things, so that those who have trusted in God may be careful to devote themselves to doing what is good. These things are excellent and profitable for everyone.
But avoid foolish controversies and genealogies and arguments and quarrels about the law, because these are unprofitable and useless.
Warn a divisive person once, and then warn him a second time. After that, have nothing to do with him. 
You may be sure that such a man is warped and sinful; he is self‑condemned.
Titus 3:1-11