How much energy is need to raise 50 kg of water from 45 c to 80c?

Energy = mass * specific heat capacity*change in temperature'

In this case, the mass of water is 50 kg, the specific heat capacity of water is 4184J/kg

the change in temperature is 80-45 = 35 degrees celcius

Therefore, heat energy

= 50 * 35 * 4184=7322000 Joules

But 1kJ = 1000 Joules

therefore, the energy needed will be 7322 kJ

Based on your problem, what you are looking for is the quantity of heat. To solve for it, you will need this formula:

Q = mc (T2-T1)

Where: Q = Quantity of heat

m = mass of the substance

c = Specific heat

T2 = Final temperature

T1 = Initial temperature

Now the specific heat of water is 4.184 J / (g°C), meaning that is how much energy is required to raise the temperature of 1g of liquid water by 1 degree Celsius.

Since your mass is in kilograms, let us convert that into grams, which will be equal to 50,000 grams. Now we can put our given into the equation:

Q = mc (T2-T1)

= 50,000g x 4.184 J / (g°C) x (80°C - 45°C)

= 50,000 g x 4.184 J / (g°C) x 35°C

= 7,322,000 J or 7,322 kJ or 7.322 MJ