No matter how much i scrape my tongue, i can't get the layer of white stuff off. is this normal?

Yes: You don't need to scrape your tongue. Usually the layer of white is just cellular debris.

It is normal: The "white stuff" is keratin from the underlying tongue tissue. Also the taste buds in the top part of the tongue are long and "finger-like." the anatomy of the taste buds and this keratin layer can sometimes make the tongue look "hairy." this is completely benign. Scrubbing your tongue is not needed and cause harm.

Hairy tongue: Causing factors for hairy tongue include poor oral hygiene, smoking, caffeine, alcohol use and the use of medications (especially broad-spectrum antibiotics), and therapeutic radiation of the head and the neck. All cases of hairy tongue are characterized by a thickening and elongation of filiform papillae, with a lack of normal desquamation.

Poor digestion: If you are interested in functional medicine try taking betaine hydrochloride 1000mg if u are <150 pounds 2000mg if you are >150-250pounds (post comment if u are over 250 pounds for specifics) after each meal - if u have discomfort due to belching with betaine hcl take bromelain orally. The coating will disappear within a week.