No, I prefer: "I am coming to the laboratory this afternoon."
It depends on the sentence: You will be coming to the lab in the afternoon! Are you coming to the lab in the afternoon? This afternoon, you will be coming the the lab, won't you?
This afternoon you are coming to the Laboratory.
His doctor ordered some lab tests, including a lipid panel and thyroid-function tests.
I've been in a lot of stress since I started to have classes early in the morning, and late in the afternoon.
you can't
The only problem with that sentence is that 'purest' is an adjective that doesn't work in this context. Maybe try something like "Distilled water is one of the most pure elements used in lab work".
The maze was inescapable for the lab rats.
He enjoyed working in the lab, so he tried his best to do his job well.
greymatter is not in yet (coming in 2011) neither does ripjaws but he is not coming ever
^ You have one right there.
I liberated some uranium from the nuclear lab.
Typically, the correct answer is 'ciencia.' This refers to the study of sciences, like biology, chemistry, etc. However if you're talking about science as an academic subject (as in going to science class), you would say 'ciencias.' For a sentence like 'I have mastered the science of making money' you would use 'el arte' instead of 'ciencia' because science in that sentence refers to a knowledge of a system.