James McConnell died of complications from aspiration pneumonia a week after the incident on 4 August 2015 at Lomond Court Care Home in Glenrothes, Fife, Scotland.
The care home's operator, HC-One, has been fined £270,000 after it pleaded guilty at Kirkcaldy Sheriff Court to breaching s 3(1) and 33(1)(a) of the Health and Safety at Work Act.
The court was told that a delivery of cleaning products, including the tablets, which were used as a disinfectant and similar in appearance to mints, had been left unattended in a corridor in an unsealed box.
Staff found the 72-year-old distressed and in pain close to where the cleaning products had been left. Three of the 200 tablets that where in the delivery were missing.
McConnell sustained burns and blisters on his tongue and vomited violently.
The Health and Safety Executive's (HSE) investigation found HC-One had not risk-assessed several of its chemical products, including the disinfectant tablets.
There was no safe system of work for the delivery of chemicals at the site, while the delivery arrangements had not been reviewed for two years.
HSE inspector Gary Miller said: "This distressing incident confirms the need for anyone handling potentially harmful substances to be extra vigilant in ensuring that they are not left unattended in circumstances where vulnerable people in their care can gain access to them.
"Sustainable procedures need to be put in place and then regularly checked to ensure they are being followed by everyone, not just for the use of such substances, but also for their delivery, storage and disposal."
