Science Question! Help!?

The specific heat capacity of water is high, 4.184 J/g�C. The presence of impurities in a sample of water lowers its specific heat capacity. What is the specific heat capacity of the sample if 100 grams of it now requires 200 Joules of heat for a 1.8�C temperature increase? What are the effects of the low specific heat capacity of the sample of water?