Derryck John, from Croydon, south London, targeted six riders in a bid to steal their vehicles in the north and east of the capital in less than 90 minutes on July 13 last year.
John, who appearded at Wood Green Crown Court via video link, carried out "grave crimes", according to Judge Noel Lucas QC.
The teenager sprayed his victims in the face with a noxious liquid, leaving one man with a 30% loss of sight in one eye.
John stole two mopeds and tried to take another four from their owners, before being arrested at around 3am on July 14.
Judge Lucas said: "Your actions on the evening of 13 July 2017 were despicable and cowardly.
"You and your accomplice chose to attack members of the public who were going about their lawful business.
"These were grave crimes. You attacked members of the public with what appears to have been an acid at the strongest end of the scale of acids.
"You have not revealed the name of your accomplice or the precise nature of the corrosive fluid used or where you and your accomplice obtained it."
The judge told John that had he been sentencing him as an adult and had he been convicted after a trial as opposed to having pleased guilty, the sentence would have been 22 years' imprisonment.
Judge Lucas described the "life-changing" and "defining" impact the incident has had on John's victims.
The judge also commented on the prevalence of acid attacks in London.
"I can state from my own knowledge of the offences arriving at this Crown Court that such offences have risen sharply in the last 12 months.
"This is the second major corrosive fluid case I have had to deal with in the past three months," he said.
The judge added: "It is clear to me that the carrying and use of corrosive liquids is rapidly becoming a serious and growing problem in London and in particular, in this part of London.
"So too are crimes committed using scooters."
Last month, John pleaded guilty to six counts of throwing a corrosive liquid with intent to "disable, burn, maim, disfigure or cause grievous bodily harm", two counts of robbery and four counts of attempted robbery.
Another unidentified person is listed on the indictment as also having been involved in the attacks.
John earlier denied the charges and had been due to stand trial.
Last month, Judge Lucas, reading a note from the defendant, said the guilty pleas were entered "on the basis that the acid was thrown to incapacitate the victims" and that "the other male involved was much older than me".
Ramesh Patel, of the CPS, said: "Derryck John claimed he was not involved in these attacks.
"CCTV from a petrol station was key to his identification and conviction.
"He was filmed stepping off a stolen Vespa scooter, lifting his motorcycle helmet and revealing his face.
"That evidence, alongside further material including CCTV of Derryck John wearing the same clothes and shoes during the other attacks, led to his guilty pleas on the first day of trial.
"One of the victims has lost 30% of his eyesight which he will never recover.
"Others described searing pain and burning at the time and have been forced to leave their jobs as a result of their injuries.
"Had they not been wearing helmets all of the victims' injuries could have been much more serious.
"Our thoughts are with them as John now faces the consequences of his appalling actions."
Earlier reporting restrictions had banned identification of the defendant due to his age.
But judge Lucas told the court last month that there was an "overwhelming, huge public interest" in identifying the teenager after he pleaded guilty to 12 counts.
In December, Arthur Collins, the ex-boyfriend of reality TV star Ferne McCann, was handed a two decades-long prison term, after a brutal nightclub acid attack.