It takes about 4.186 joules to heat one gram of water by 1 deg Celsius. M
0.50 liters is 500 grams, and you want to hear that by 10C. So, multiply 4.186 by 500*10 the answer is about 4.186*500*10=20930 joules.
If you give 1100 joules per second, it will take 20930/1100=19.027 seconds to supply enough energy.