This is the Golden Sequence sung each day of the Easter Octave in the Old Latin Mass.
Here's a rather echo-y recording alternating between ladies and mens voices:
This piece is sort of the responsorial psalm equivalent for the Old Latin Mass for Easter Week.
It's the first really melismatic piece I ever learned - so proud :) The tricky bit is not running out of breath for that last syllable.
This is the Hymn for the Holy Spirit - in case of Confirmations, or just because we need the Holy Spirit All The Time!
The Easter Marian Antiphon - there are 4 special chant antiphons to Mary for different parts of the Church's year.
Here's another sung by older voices