Calculate the amount of heat required to raise the temperature of a 25 sample of water from 7 to 25.

q = m x Cg x (Tf - Ti)

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To calculate the amount of heat required to raise the temperature of a substance, you need to use the specific heat formula. The specific heat of water is 4.18 J/g°C.

The specific heat formula is:
q = m * c * ΔT

Where:
q = heat energy (in joules)
m = mass of the substance (in grams)
c = specific heat capacity of the substance (in J/g°C)
ΔT = change in temperature (in °C)

In this case, the mass of the water sample is 25 grams, and the change in temperature is from 7°C to 25°C. Let's substitute these values into the formula:

q = 25 g * 4.18 J/g°C * (25°C - 7°C)
q = 25 g * 4.18 J/g°C * 18°C
q = 1881 J

Therefore, the amount of heat required to raise the temperature of a 25 g sample of water from 7°C to 25°C is 1881 Joules.