Yes, you can use 2Amps charger to charge your phone, as long as the output voltage of the charger matches with the input voltage of your device.
If your mobile is 5V, then any charger of 5V can be used to charge your mobile. But, remember, if you use a less Amps charger, it will take long time for charging. Some devices might not charge if the current (Amps) supplied to less for that battery. Example, it would sound ridiculus to charge your Tablet, whose original charger is rated at 2.5Amps, with your mobile charger whose rating is 0.5 Amps (i.e., 500 mA. Please note 1 A = 1 Amp = 1000 mA).
You can always your Galaxy Note, Samsung SIII or your favorite HTC mobile - say, HTC OneX with the charger of a BlackBerry Play Book, which is rated at 2Amps.
There is one simple rule - As long as the charging socket fits the charging pin, it is, generally okay to use that charger.