Learn Hardcore Turkish: Elimi sabunla yıkayıp duruladım. - I washed my hands with soap and rinsed them.

Because elimi is the direct object and needs the accusative case suffix -i. You also add the possessive suffix -im for “my,” so you get el (hand) + -im (my) + -i (accusative) = elimi.

What does sabunla mean and why -la?

The suffix -la marks the instrumental case, meaning “with.” So sabunla = “with soap.” You could also say sabun ile, but sabunla is shorter and very common.

What is the function of -ıp in yıkayıp?

The -ıp (or -ip) ending is a converb that links two verbs and shows that the first action happens before the second. Yıkayıp here means “having washed” or simply “wash and then…,” connecting to duruladım (“I rinsed”).

Why not yıkadım instead of yıkayıp?

If you say yıkadım, the sentence ends at the washing: Elimi sabunla yıkadım = “I washed my hand with soap.” Using yıkayıp lets you join another verb: “I washed my hand with soap and (then) rinsed it.”

What does duruladım mean and what tense is it?

Durulamak means “to rinse off” (to wash away soap). Duruladım is the simple past tense for first person singular: durula (root) + -dı (past) + -m (1 sg) = “I rinsed (it).”

Why is it elimi in singular? Can you say ellerimi?

Yes, you can say ellerimi (“my hands”) too. Using elimi (singular) is idiomatic: the singular word el can refer to both hands collectively. Context tells you it’s both.

Could you rephrase yıkayıp duruladım with another structure?

Absolutely. You can use the -dıktan sonra (“after …”) construction:
Elimi sabunla yıkadıktan sonra duruladım = “After washing my hand with soap, I rinsed it.”