Help with Chemistry!?

Question

1. How many joules of energy are required to raise the temperature of 65 g of iron from 25 C to 95 C?

2. The specific heat of zinc is 0.096 cal/g C. Determine the energy required to raise the temp of 250.0 g of zinc from room temp (24C) to 150C.

3. One gram of anthracite coal gives off 7000. cal when burned. How many joules is this? How many grams of anthracite are required to raise the temp of 4.0 L of water from 20.0 C to 100.0 C?

Please show work to help me understand better how to complete these type of questions.

Answer 1

1. spec. heat is 0.45 J/g*K so 0.45*65*(95-25) = 2047.5 J (2050 to 3 sig figs)

2. 0.096*250*(150-24) = 3024 (to 4 sig figs)

3a. 29288 J (30000 to 1 sig fig)

3b. 4000*80/7000 = 45.71 g (46 to 4 sig figs because 100.0 was a specified temperature)