Final answer:
To change 15.4 g of water from 22.2°C to 25.6°C, 218.78 joules are needed, calculated using the heat energy equation q = mcΔT with the specific heat capacity of water being 4.184 J/g°C.
Step-by-step explanation:
To calculate how many joules are needed to change the temperature of 15.4 g of water from 22.2°C to 25.6°C, we use the equation q = mcΔT, where ‘q' represents the heat energy, ‘m’ is the mass of water, ‘c’ is the specific heat capacity of water, and ΔT is the change in temperature. The specific heat capacity of water is known to be 4.184 J/g°C. The mass ‘m’ is 15.4 g and the temperature change ΔT is 25.6°C - 22.2°C, which equals 3.4°C.
Plugging these values into the formula, we get:
q = 15.4 g * 4.184 J/g°C * 3.4°C
q = 15.4 * 4.184 * 3.4
q = 218.7832 J
Therefore, 218.78 joules are needed to change the temperature of 15.4 g of water from 22.2°C to 25.6°C.