Which date is "mi'Mochoras" referring to?
Rashi (in 33:11): On the seventeenth of Tamuz, Moshe broke the Luchos, on the eighteenth, he burned the calf and on the nineteenth, 1 he ascended Har Sinai for the second time.
Refer to 32:30:6:2 & 3.
What are the connotations of "Chata'ah Gedolah"?
Seforno: Refer to 32:21:1:3**.
Why did Moshe mention 'Chata'ah Gedolah' to the people?
Seforno: To make them aware of the magnitude of the sin, to encourage them to do Teshuvah. 1
As in Tehilim, 51:5 and in Yirmiyah, 3:13 (Seforno).
What are the connotations of the word "Achaprah be'Ad Chataschem"?
Rashi: Moshe was saying that he would place an atonement, a cleansing and a stopper between Yisrael and their sin. 1
Mizrachi: Since the Torah inserts the word 'be'Ad', "Achaprah" cannot mean 'I will atone?. Rashi ha'Shalem: 'Kofer' and 'Kinu'ach' refer to removal, like "Achaprah Panav" in Bereishis 32:21 in connection with Eisav, wich means to nullify his anger (Rashi there).
Seeing as Hashem had already forgiven Yisrael (in Pasuk 14), what did Moshe hope to achieve by ascending Har Sinai again?
Rashi (in Yirmiyah, 15a): To Daven on behalf of Yisrael - after he had atoned for them by killing the sinners and making them drink the dust of the Eigel with water like Sotos.
Oznayim la'Torah: He wanted an assurance that Hashem would still give them Eretz Cana'an. 1
How did Moshe intend to cleanse Yisrael by ascending Har Sinai?
Targum Yonasan: By means of Tefilah.
How long did Moshe spend on Har Sinai the second time?
Ramban #1 (in 33:7): He ascended the mountain on the eighteenth of Sivan and returned on the same day, 3 remaining in the camp until Rosh Chodesh Elul. 4
Ramban #2 (in 33:7, citing Pirkei de'R. Eliezer): He only went up the second time on Rosh Chodesh Elul. 5
In Shir Hashirim, 3:2, Rashi explains that Moshe ascended Har Sinai the second time on the eighteenth of Tamuz.
See Rashi there.
Refer to 33:11:4:2*.
See Ramban 33:7 DH 've'Ra'isi', DH 've'Im Kein' (and Rav Chavel's footnotes).
