Safe to leave 'new' chicken stock in rice cooker for three hours?
The packaged stock will be pasteurised, leaving it in a pan for a couple of hours is unlikely to allow a huge amount of bacteria growth from ambient air. Then cooking the rice will boil the stock and kill anything that has grown anyway, so it is perfectly safe. The only drawback sometimes is that the celery stick in a stock introduces a sour taste as it ages but that is with fresh celery (shop bought is likely to be powder-based) and then it only happens after about 5 days in the fridge...