@Fordprefect explained again and again you cannot ctb by snorting.
With taking that much through the nose, much, if not most, will run done the throat and then be oral. Much heroin is of less than 30% purity and it's oral availability is less than 35% (as low as 23% in some opiate naive individuals). With impurity and oral administration, the 2 g of product is about 200 mg or less of diamorphine while according to Pschonautwiki
Some sources quote the median lethal dose (for an average 75 kg opiate-naive individual) as being 75 and 600mg.
In part opioids are unreliable for death because of the great variability of their action on different individuals.
A great source for the pharmadynamics and action of heroin is the drug bank. Injecting raises the potency substantially.
Diamorphine is an opioid analgesic agent used in the relief of severe pain associated with surgical procedures, myocardial infarction or pain in the terminally ill and for the relief of dyspnea in acute pulmonary edema.
www.drugbank.ca